Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
  • H05B6/70—Feed lines
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
  • H05B6/78—Arrangements for continuous movement of material
  • H05B6/786—Arrangements for continuous movement of material wherein the material is moved using mechanical vibrations of plates

Definitions

• Embodiments of the invention are directed to microwave-based material treatment systems and methods.
• Such treatment may involve, for example, heating, dewatering, drying, sterilizing, or conversion prior to its end use or prior to further processing.
• These settings may include, for example and without limitation, industrial or building materials manufacturing, food processing, wastewater treatment, environmental remediation, coal gasification, and energy feedstock development.
• sludge may also be dewatered in disposable geotextile dewatering bags or spread within special dewatering pits, both of which require significant space, result in a slow dewatering process, and also require the addition of a polymer coagulant.
• microwave-based systems and methods for treating materials have been developed.
• microwave energy is directed at a material of interest as it is maintained in a stationary position within a microwave chamber or as the material is moved through a microwave chamber on a conveyor belt.
• the microwave energy heats the material in a manner that is dependent on the waste material at issue and the specific method of treatment.
• waste stream materials may lend themselves well to microwave-based conversion.
• the microwave energy acts to convert the carbonaceous material into various other solid, liquid, and gaseous materials, such as carbon black, oil, and gaseous hydrocarbons.
• One carbonaceous waste stream material of particular interest is scrap tires and waste rubber.
• the rubber compounds from which vehicle tires are made are very durable and may take hundreds of years to decompose. Further, the rubber compounds in tires also contain materials that can be hazardous to the environment and may be highly flammable, which has in the past led to large tire pile fires that have burned for extended periods of time. Scrap tires are also notorious collectors of rain water and are a known breeding ground for mosquitoes and West Nile virus. For at least these reasons, it is particularly undesirable to bury scrap tires in traditional landfills. Because of the difficulty and dangers associated with tire disposal, the lengthy decomposition period associated with tire materials, and the nearly one billion tires that are disposed of annually, the number of scrap tires available for microwave-based conversion may be in the hundreds of millions or more.
• microwave energy In addition to the use of microwave technology for actual conversion of waste stream materials, it may also be desirable to use microwave energy to heat treat other, non-waste, materials. For example, material heating is required in processes as diverse as coal gasification, and the cooking and/or tempering of foodstuffs.
• microwave-based systems and methods of material conversion and/or heat treatment have proven to be or are likely superior to traditional incineration, pyrolysis, or heating methods
• known microwave-based techniques are not without problems. These problems include, without limitation, the ability to finely control movement of the waste material through a microwave application section of a system, and ensuring even heating throughout the thickness of the layer of material that is subjected to microwave irradiation.
• a feedstock comprising a material(s) of interest is provided to and irradiated by the system, and the irradiated material is subsequently removed (e.g., discharged) from the system.
• a common requirement of an exemplary system may be that microwave energy is preferably prevented from migrating out of designated parts of the system (e.g., a microwave application chamber), as stray microwave energy poses a human health hazard.
• the walls of the microwave application chamber of such a microwave-based material treatment system may be made of microwave impervious materials and may be dimensioned and located so as to minimize the leakage of microwave energy from the chamber.
• Pin-choke beds may be located adjacent the infeed and discharge ends of such a microwave application chamber to further contain microwave energy that might otherwise leak from the infeed and discharge openings associated with the microwave application chamber.
• Various types of air-tight valves - which may be used on sealed and purged systems - may also block the migration of microwave energy.
• valves While gas-tight valves may prohibit the migration of stray microwave energy, the valves must remain closed while an associated microwave energy source(s) is energized. Consequently, feedstock material may not be passed through such a valve during microwave irradiation of material already present in the microwave irradiation chamber or irradiation section of the system - which dictates that a start-stop process rather than a truly continual process be employed.
• Exemplary system and method embodiments described and shown herein may overcome any or all of these and other problems associated with known microwave-based material conversion or heating systems and methods. Consequently, systems and method embodiments of the invention may be used in the industrial or building materials manufacturing, food processing, wastewater treatment, environmental remediation, and coal gasification processes mentioned above, as well as other processes where a material of interest must be heated.
• Embodiments of the invention include systems and methods for the microwave heating and/or conversion of various materials such as, but not limited to, carbonaceous materials.
• materials such as, but not limited to, carbonaceous materials.
• One such non-limiting example of a carbonaceous material that is well-suited to microwave conversion, is the rubber compound of common vehicle tires.
• System and method embodiments of the invention may be used to convert scrap vehicle tires into useful products such as, for example, gaseous and liquid fuels, and commodity products such as carbon black and activated carbon.
• An exemplary system may be designed and operated to provide a stand-alone conversion process.
• An exemplary system will generally but not necessarily have a feed hopper or a comparable device for receiving and controllably distributing a feedstock in the form of a material of interest.
• the feed hopper will receive a feedstock of shredded/pulverized tire material.
• the feed hopper may, depending on the material being processed, direct the material through a sealed inlet mechanism into a gas-tight receiving/processing section of the system that is purged with a gas, preferably an inert gas.
• material is pre-heated by ambient heat in the receiving section and then moved into and through a microwave application section of the system, where the material is irradiated with microwave energy.
• the microwave energy efficiently excites the molecules within the scrap tire material to a point where molecular bonds are broken and the result is a byproduct or byproducts that are intended to be commercially useful.
• the treated material may in some embodiments be moved into a cooling section of the system, and eventually removed. In other cases, a system cooling section and an associated cooling process may be omitted. Liquid and/or gaseous byproducts of conversion may be removed from the system at various times and locations.
• exemplary embodiments of the invention may be directed to systems and methods for the microwave heating and treatment of various materials.
• a material of interest is heated to elevate its temperature by subjecting the material to microwave irradiation.
• the irradiation process may occur in an oxygen- containing environment or in an inert and substantially oxygen free environment.
• a heating embodiment is a sterilization embodiment, wherein a material to be sterilized is subjected to microwave irradiation in an inert and substantially oxygen free environment and its temperature is raised to a point sufficient to eliminate certain possible contaminants, bacteria, etc.
• a material that is well- suited to sterilization by microwave irradiation is a foodstuff.
• Another exemplary embodiment is a dewatering embodiment, wherein a material to be dewatered may be subjected to microwave irradiation for the purpose of removing some amount of water therefrom.
• a pre-irradiation dewatering grate or another similar mechanism(s) may be employed upstream of the microwave applicator portion of the associated system to assist with dewatering.
• a material that is well-suited to dewatering by microwave irradiation is wastewater sludge.
• water is removed from the wet sludge material by microwave heating to produce a processed sludge that is sufficiently dried and sterilized for landfill deposit or a dewatered cake that is sufficiently dry for incineration.
• Microwave processing of wastewater sludge may also provide the benefit of eradicating bacteria or other objectionable sludge ingredients, possibly rendering the sludge acceptable for use as a fertilizer or otherwise sufficiently innocuous for alternative disposal methods.
• a dewatering system and method embodiment may also be well-suited for removing moisture from coal prior to its pulverization and/or burning as a fuel.
• Another exemplary embodiment is a sorting/sifting embodiment, wherein a material to be heated or dried may be sorted/sifted prior to being subjected to and heated by microwave irradiation.
• the material of interest may pass over a sorting/sifting grate or screen while being conveyed to a microwave applicator portion of the system. This allows smaller, deleterious, or otherwise undesirable elements of the material of interest to be removed prior to microwave irradiation of the remaining, desirable portion of the material of interest.
• the sorted/sifted material may be routed to another location, may be collected separately from the irradiated material of interest, etc.
• Non-limiting examples of such system and method embodiments of the invention may find use in cement kilns and asphalt plants, in the treatment of wastewater sludge, in the remediation of contaminated soils, and in processes for preparing coal or sterilizing foodstuffs.
• Yet another exemplary embodiment is directed to the drying of a material of interest with the additional use of a fluidized bed.
• the conveyor by which the material is transported through the system, or at least through the microwave applicator section thereof is part of a fluidized bed by which warm air from a heat source is directed through the underside of the conveyor to assist with drying.
• a plenum may be provided below the conveyor to receive and distribute the warm air through the conveyor.
• Non-limiting examples of such system and method embodiments of the invention may find use in the treatment of wastewater sludge, in the remediation of contaminated soils, and in processes for preparing coal or sterilizing foodstuffs.
• material treatment in the form of material conversion may also be useful.
• Improved systems and methods that use microwave energy to heat and/or convert carbonaceous materials such as the rubber compound of common vehicle tires are described and illustrated in U.S. provisional Application No. 61/942,183, filed on February 20, 2014, which is hereby incorporated by reference in its entirety.
• U.S. provisional Application No. 61/942,183 filed on February 20, 2014, which is hereby incorporated by reference in its entirety.
• several exemplary embodiments of improved systems and methods that use microwave energy to heat, dewater, dry, or sterilize various materials are described and depicted in U.S. provisional Application No. 62/042,289, filed on August 27, 2014, which is also hereby incorporated by reference in its entirety.
• These exemplary microwave-based material treatment systems and methods employ a novel material transport mechanism in the form of a vibratory conveyor.
• material to be processed may be transported through a system of the invention in a highly novel manner.
• exemplary system embodiments according to the invention may make use of a vibratory material transport mechanism.
• the vibratory material transport mechanism is a vibratory conveyor having a vibratory drive system that is in communication with a conveying trough or table upon which the material of interest rests and moves.
• the vibratory conveyor may extend the full length of the system - from a receiving (e.g., pre-heat) section, through a microwave application section, and into a cooling and material removal section.
• the vibratory conveyor may be used only in the microwave application section, with the material of interest being transferred to and from the vibratory conveyor by other means.
• the vibratory drive system of the vibratory conveyor allows the movement of the material along the conveyor trough/table to be finely controlled. Both very fast and very slow transport speeds are achievable, as is virtually any speed in between, and material transport programs comprising a combination of various material transport speeds may be employed.
• the use of a vibratory conveyor allows the material of interest to be mixed by vibration while being transported through the system.
• the material of interest may also be mixed by vibration of the vibratory conveyor when the material is in a stationary state with respect to forward or rearward movement thereof. Such mixing promotes a more even absorption of microwave energy by the material, from the top to the bottom of the material layer.
• the use of a vibratory conveyor also eliminates the return path required by an endless belt conveyor and the complexities, limitations, and inefficiencies associated with the use of removable trays.
• the trough/table of a vibratory conveyor of a system embodiment may be provided with one or more ramps or similar features along its length, at least in the area of microwave application. These ramps act to further mix the material by causing a tumbling thereof, and also variably alter the distance of the material from the microwave source(s) as the material moves through the microwave applicator section.
• the trough/table of a vibratory conveyor of a system of the invention may be provided with one or more directing channels or other guideways in addition to or in lieu of the aforementioned ramps.
• These material directing channels function to cause a movement of the material of interest in a direction other than the normal conveying direction. More specifically, the material directing channels are sized and oriented to cause at least a portion of the material of interest to move transversely (e.g., laterally or diagonally) to the normal conveying direction as the material moves through the microwave application section. The effect of this transverse movement is to additionally mix the material of interest so as to further promote the absorption of microwave energy thereby.
• Embodiments of the invention also include novel designs for isolating various system components from the oscillating effects of the vibratory conveyor, such as those shown in U.S. Provisional Patent Application No. 61 /942,1 83, filed on February 20, 2014.
• a specialized design and construction allows the waveguides of the microwave applicator to be secured in a stationary manner while simultaneously being isolated from the effects of the vibratory conveyor.
• a unique expansion joint construction is employed for this purpose.
• the expansion joints are preferably of metal construction, so as to contain both emitted microwave energy and any vapors that are produced during material treatment.
• a similar design and construction may also be used to isolate other, upstream and/or downstream, components.
• Exemplary system embodiments according to the invention may be designed and operated to provide a stand-alone material treatment process. Furthermore, exemplary system embodiments according to the invention may be made portable so as to be delivered to and operated at or near the location of a given material to be treated. Portability may be especially beneficial in, for example, embodiments used to remediate contaminated soil, etc.
• exemplary microwave energy containment device embodiments are provided in the form of tubular baffles that are properly dimensioned to block the passage therethrough of microwave energy of a given wavelength.
• a collection or array of tubes each having some predetermined diameter and length are arranged in a rectangular pattern so as to collectively fit within a rectangular pipe or conduit (e.g., infeed conduit or discharge port) of an associated microwave-based material treatment system.
• a plurality of such tubes may be arranged in other patterns, such as a square, rectangle, or other geometric shape.
• the dimensions of the individual tubes (or single tube) are selected so as to prevent the passage therethrough of the wavelength of microwave energy to which the microwave energy containment device will be exposed.
• Microwave energy containment device embodiments according to the invention may be placed in the feedstock material infeed pathway and/or the processed material discharge pathway of a microwave-based material treatment system in order to prevent the migration of microwave energy therethrough.
• microwave energy containment devices are able to block the unwanted migration of microwave energy while simultaneously permitting the passage therethrough of both gaseous and solid materials.
• the microwave energy containment devices used in systems of the invention are "pass-through" devices with respect to the feedstock and/or processed material being treated. Consequently, microwave blocking is not dependent on maintaining a proper feedstock depth and there is no need to stop the infeed or discharge flows of feedstock material as there is when gas-tight valves are used for microwave energy containment. This permits microwave-bases system embodiments of the invention to process materials with an increased throughput in comparison to systems employing traditional pin-choke beds.
• An exemplary system embodiment will generally have a material receiving section, which may or may not include a feed hopper or a comparable device for controllably distributing a feedstock in the form of a material of interest.
• the material being processed may be directed through a sealed inlet mechanism or otherwise delivered into a gas-tight receiving/processing section of the system that is purged with a gas, preferably an inert gas.
• the material receiving section of the system may not be gas tight and may be non-purged.
• the receiving section of an exemplary system may be open to the atmosphere, whereby material to be processed may be deposited directly onto an exposed conveyor belt, a receiving portion of the vibratory conveyor, or some other material infeed mechanism.
• the treated material may in some embodiments be moved into a cooling section of the system. In other cases, a system cooling section and an associated cooling process may be omitted. In any case, the processed material is eventually discharged from the system, such as by being conveyed to a discharge section and deposited into collection vessels, etc. Liquid and/or gaseous byproducts of conversion may also be removed from certain embodiments of the system at various times and locations.
• a material that is particularly appropriate for microwave conversion is the rubber compound of scrap tires.
• systems and method embodiments of the invention are not limited to the conversion of tire material. Rather, systems and methods of the invention may be used to process (e.g., heat, convert, pyrolize, sterilize, etc.) a variety of materials, including but not limited to, scrap tires, waste rubber from other products or manufacturing processes, waste plastics and polymers, asphalt shingles, e-waste, medical waste, municipal sludge, oil/shale drilling waste, coal (e.g., for gasification), and foodstuffs. It is contemplated that systems and methods of the invention may also serve a role in more complex systems and processes for producing activated carbon from one or more of various carbonaceous materials that would be well known to one of skill in the art.
• FIG. 1 is a transparent side view of one exemplary embodiment of a microwave-based material processing system
• FIG. 2 is an end view taken along Section 1 , as indicated in FIG. 1 ;
• FIG. 3 is an end view taken along Section 2, as indicated in FIG. 1 ;
• FIG. 4 is an enlarged view of a vibratory isolator being used to isolate a waveguide of the system from the effects of vibratory movement;
• FIG. 5 is a transparent side view of one exemplary embodiment of a microwave-based material processing system for performing a dewatering operation
• FIG. 6 is a transparent side view of one exemplary embodiment of a microwave-based material processing system for performing a sterilizing operation
• FIG. 7 is a transparent side view of one exemplary embodiment of a microwave-based material processing system that includes sorting/sifting functionality
• FIG. 8 is a transparent side view of one exemplary embodiment of a microwave-based material processing system for performing a drying operation, and which includes a fluidized bed microwave applicator;
• FIG. 9 is a transparent side view of one exemplary embodiment of a microwave-based material processing system for performing a dewatering operation;
• FIG. 10 is a transparent side view of one exemplary embodiment of a microwave-based material processing system for performing a sterilizing operation
• FIG. 1 1 is a transparent side view of one exemplary embodiment of a microwave-based material processing system that includes sorting/sifting functionality
• FIG. 12 is a transparent side view of one exemplary embodiment of a microwave-based material processing system for performing a drying operation, and which includes a fluidized bed microwave applicator;
• FIG. 13 is a transparent side view of one exemplary embodiment of a microwave-based material processing system for converting scrap tire material
• FIGS. 14A-14B are a side view and a front view, respectively, of one exemplary embodiment of a pass-through microwave energy containment device.
• FIGS. 15A-15B illustrate possible but non-limiting cross-sectional shapes of exemplary pass-through microwave energy containment devices and the components thereof. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT(S)
• FIGS. 1 -3 One exemplary embodiment of a microwave-based material processing system 5 is depicted in FIGS. 1 -3.
• this particular embodiment includes a feed hopper 1 0 for receiving and distributing a material (feedstock) of interest.
• the feed hopper 10 is located directly above an inlet section 15 of the system 5.
• the feed hopper 10 may be offset from the inlet section 1 5 of the system 5, in which case a conveyor, chute or some other device may be interposed between the feed hopper and the system inlet to transfer the feedstock therebetween.
• the inlet section 15 of the system 5 may include a sealed inlet mechanism 20 that helps to create a gas-tight feedstock receiving chamber 25 within the system.
• the gas-tight feedstock receiving chamber 25 may be purged, preferably with an inert gas.
• the feedstock receiving chamber 25 is also a pre-heat chamber that is operative to raise the temperature of the feedstock that resides therein prior to the feedstock being transferred to a downstream microwave applicator chamber 30 of the system 5.
• the pre-heat chamber 25 may include its own heat source and/or may receive heat collected from the downstream microwave applicator chamber 30 and/or a cooling chamber 70 of the system 5.
• the feedstock is transferred from the pre-heat chamber 25 and transported through the system 5 by means of a vibratory conveyor 35 having a vibratory drive system that is in motive communication with a conveying trough (or table) 40 upon which the feedstock material rests and moves.
• the vibratory drive system may reside beneath the conveying trough or in a location other than beneath the conveying trough in different system embodiments.
• the vibratory drive system may include one or more vibratory motors for initiating and sustaining the driving motion of the conveyor, but embodiments of the invention are not limited to any particular vibratory drive system design. In any case, the vibratory drive system is normally operative to produce the overall vibrating motion that induces movement of the feedstock.
• a variable frequency drive is also preferably used to control the vibratory conveyor so as to allow for a wide range of possible conveying speeds. Both very fast and very slow transport speeds are achievable, as is virtually any speed in between, and material transport programs comprising a combination of various material transport speeds may be employed. It is also possible to produce both a gentle forward motion of the material or a more abrupt and severe jump forward.
• use of the vibratory conveyor 35 and its associated variable frequency drive allows the feedstock material of interest to be mixed by vibration while being transported through the system, or to be mixed by vibration while held in a stationary position. Such mixing promotes a more even heating of the material from the top to the bottom of the material layer.
• a vibratory conveyor can convey virtually any type of material. Vibratory conveyors are also inherently self-cleaning, experience very little wear of the conveying surface, and cause very little damage or degradation to the material being transported. If necessary, the conveying surface may also be easily modified to permit the conveying and processing of feedstock across a very wide temperature range (e.g., up to thousands of degrees Fahrenheit). For example, for this and other reasons, the conveying surface of a vibratory conveyor embodiment may be lined with ceramic tiles or other materials that protect the conveying surface and/or aid in material movement across the conveying surface.
• the vibratory conveyor 35 extends the full length of the system 5 - from the pre-heat chamber 25, through the microwave application chamber 30, and into the cooling and material removal chamber 70.
• the vibratory conveyor may extend only within the microwave application chamber, with the material of interest being transferred thereto from a receiving chamber and/or being removed therefrom to a cooling chamber by other means.
• the end walls 45 of the microwave application chamber 30 preferably project down to the top of the feedstock layer (bed) being moved through the system 5.
• This design acts to prevent microwave energy from leaving the microwave application chamber 30 and entering the pre-heat chamber 25 or cooling chamber 70.
• a pin-choke bed 72 may be installed on either side of the applicator chamber to similarly inhibit or eliminate the migration of stray microwave energy into adjacent spaces.
• At least the walls of the microwave application chamber 30 are also preferably comprised of a material that does not pass microwave energy, or are otherwise lined or coated to produce the same effect. In the exemplary system 5, at least the walls of the microwave application chamber 30 are manufactured from stainless steel.
• the microwave application chamber 30 is shown to include a plurality 30 of gas ports 55 that are provided to vent gaseous byproducts of the microwave irradiation process from the microwave application chamber.
• the gaseous byproducts may be captured, condensed, scrubbed, and/or otherwise acted upon in various fashion.
• the captured gaseous byproducts may be sold or may be used as a fuel to generate electrical energy for powering the microwave applicator and or other components of the system 5.
• the microwave application chamber 30 may be purged with a preferably inert gas so as to help reduce any chances of feedstock combustion or recombination of the off-gases with oxygen.
• the microwave application chamber 30 can also be seen to be associated with microwave waveguides 60 that direct microwave energy from a microwave source (not shown) through corresponding entry points 65 in the overhead chamber wall.
• the waveguides and entry points may have other shapes, locations and orientations in other system embodiments.
• the waveguides may be protected from reflected microwave energy by any of the techniques that would be well known to one of skill in the art.
• the conveying surface (trough) 40 of the vibratory conveyor 35 upon which the feedstock material rests and moves may be optionally provided with one or more ramps 50 or similar features along its length, as is best illustrated in FIG. 1 .
• the ramps 50 act to further mix the feedstock material by causing a tumbling thereof as the material falls from one ramp to the next or from a ramp to a flat portion of the vibratory conveying surface.
• the ramps 50 also have the effect of variably altering the distance of the feedstock material from the entry points and reflection points of the microwave energy within the microwave application chamber 30 as the feedstock material moves therethrough.
• system embodiments may also be provided with one or more directing channels or other guideways that function to cause a movement of the material of interest in a direction other than the normal conveying direction. More specifically, the material directing channels are sized and oriented to cause at least a portion of the material of interest to move transversely (e.g., laterally or diagonally) to the normal conveying direction as the material moves through the microwave application section. The effect of this transverse movement is to further mix the material of interest so as to promote an even absorption of microwave energy thereby.
• Such material directing channels or other guideways may be located in/on the conveying surface of the vibratory conveyor 35.
• the material directing channels may be located to pass over the conveying surface of the ramps 50, or the material directing channels may be arranged to avoid the ramps.
• the remainder of the microwave irradiated feedstock material is transferred by the vibratory conveyor to a cooling chamber 70 where the material is allowed to cool sufficiently before being removed through an outlet section 75. It is expected that a majority if not all of the remaining material that is transferred to the cooling chamber 70 will be in solid form. However, this may not necessarily be the case depending on the nature of the feedstock material that is processed.
• the outlet section 75 of the system 5 may include a sealed outlet mechanism 80 that helps to create a gas- tight cooling chamber 70.
• the cooling chamber 70 may also be purged, preferably with an inert gas.
• the system 5 also includes a novel means for isolating various system components from the vibratory effects of the vibratory conveyor 35.
• a novel design and construction allows the waveguides 60 of the microwave applicator to be secured in a stationary manner while simultaneously being isolated from the effects of the vibratory conveyor 35.
• the waveguide 60 is secured to a stationary support deck 85 of the system frame 5 by a flanged arrangement 90.
• the support deck 85 maintains the waveguide 60 in a stationary position.
• a hollow pipe section 1 00 is welded to the underside of the support deck 85 so as to provide a sealed tunnel for the waveguide 60 to pass through.
• a lower flange 105 of the hollow pipe section 100 connects to an upper flange 1 15 of an expansion joint 1 10, which also includes a lower flange 120 for connection of the expansion joint to a connector 125 extending from the upper wall of the microwave application chamber 30.
• This design allows the vibratory movement of the vibratory conveyor 35 to be absorbed by the expansion joint 1 1 0 instead of being transferred to the waveguides 60.
• This design also provides for a sealed waveguide pathway between the microwave source and the microwave application chamber 30.
• the expansion joints 1 10 are preferably of metal construction, so as to contain both microwave energy and any vapors that are produced during feedstock processing.
• a similar expansion joint design and construction may also be used to isolate other, upstream and/or downstream, components.
• an expansion joint is also located between the feed hopper 1 0 and the pre-heat chamber 25 and between the cooling chamber 70 and the outlet mechanism 80 of the system 5.
• scrap tires are a particularly attractive, but certainly not exclusive, feedstock material that may be processed by a system and method of the invention.
• the feed hopper 10 would receive a feedstock of shredded/pulverized tire material and direct the tire material through the sealed inlet mechanism 20 and into the preheat chamber 25, which is purged with an inert gas.
• the tire material is moved into and through the microwave application chamber 30 by the vibratory conveyor 35.
• the microwave application chamber 30 As the material passes through the microwave application chamber 30, it is heated by microwave irradiation to a desired temperature for a desired amount of time, so as to convert (depolymerize) the tire material.
• the microwave energy may be transmitted to the microwave application chamber 30 via bifurcated waveguides, such that the microwaves enter the microwave application chamber in parallel alignment and at a frequency between approximately 894 MHz and approximately 1 ,000 MHz.
• the microwave energy will most likely be directed at the tire material feedstock from above the vibratory conveyor 35 and possibly also transversely thereto. In either case, it is contemplated that the microwave energy will be directed at an angle that is substantially perpendicular to the direction of travel of the feedstock.
• the microwave energy will liberate the hydrocarbon content in the material to result in a hydrocarbon vapor that is split into gaseous and/or liquid fuels after exiting the microwave chamber 30, as well as commodity products such as carbon black.
• the system 5 removes the hydrocarbon content to derive the liquid and gaseous end products. Solid materials, such as carbon black, that remain on the conveying surface of the vibratory conveyor will be passed to the cooling chamber 70, where the materials are cooled before being released through the gas-tight outlet mechanism 80 into a collection hopper 140 for removal and downstream handling and processing.
• FIGS. 5-8 Additional various exemplary embodiments of microwave-based material processing systems according to the invention are depicted in FIGS. 5-8.
• microwave irradiation systems and methods according to the invention may be used in applications such as heating, dewatering, drying, sterilizing, and converting in settings that may include, for example and without limitation, industrial or building materials manufacturing, food processing, wastewater treatment, environmental remediation, coal gasification and energy feedstock development (e.g., drying algae or cellulosic wood pulp to create an energy-producing feedstock for other processes).
• industrial or building materials manufacturing e.g., food processing, wastewater treatment, environmental remediation, coal gasification and energy feedstock development (e.g., drying algae or cellulosic wood pulp to create an energy-producing feedstock for other processes).
• energy feedstock development e.g., drying algae or cellulosic wood pulp to create an energy-producing feedstock for other processes.
• these exemplary embodiments are not to be construed as limiting in scope.
• the material being processed i.e., the feedstock
• the material being processed is transported through the system, or at least through a microwave applicator portion of the system, by means of a vibratory conveyor having a vibratory drive system that is in motive communication with a material-carrying portion (e.g., a conveying trough or table) upon which the feedstock material rests and moves.
• the vibratory drive system may reside beneath the material-carrying portion or in a location other than beneath the material-carrying portion in different system embodiments.
• the vibratory drive system may include one or more vibratory motors for initiating and sustaining the driving motion of the conveyor, but embodiments of the invention are not limited to any particular vibratory drive system design. In any case, the vibratory drive system is normally operative to produce the overall vibrating motion that induces movement of the feedstock.
• a variable frequency drive is also preferably used to control the vibratory conveyor so as to allow for a wide range of possible conveying speeds. Both very fast and very slow transport speeds are achievable, as is virtually any speed in between, and material transport programs comprising a combination of various material transport speeds may be employed. It is also possible to produce both a gentle forward motion of the material or a more abrupt and severe jump forward. Furthermore, use of the vibratory conveyor and its associated variable frequency drive allows the feedstock material of interest to be mixed by vibration while being transported through the system, or to be mixed by vibration while held in a stationary position. Such mixing promotes a more even heating of the material from the top to the bottom of the material layer.
• a vibratory conveyor can convey virtually any type of material. Vibratory conveyors are also inherently self-cleaning, experience very little wear of the conveying surface, and cause very little damage or degradation to the material being transported. If necessary, the conveying surface may also be easily modified to permit the conveying and processing of feedstock across a very wide temperature range (e.g., up to thousands of degrees Fahrenheit). For example, for this and other reasons, certain system embodiments may include a vibratory conveyor conveying surface that is lined with ceramic tiles or other materials that protect the conveying surface and/or aid in material movement across the conveying surface.
• the vibratory conveyor may extend the full length of the system - from a receiving section, through the microwave applicator, and into a post-irradiation (e.g., cooling) section. In other embodiments, the vibratory conveyor may extend only through the microwave applicator, with the material of interest being transferred thereto from a receiving section and/or being removed therefrom to a cooling chamber or post- irradiation section of the system by other means.
• a post-irradiation e.g., cooling
• FIG. 5 A first exemplary microwave-based material processing system 5 is shown in FIG. 5. This particular embodiment is designed for use in a dewatering application, although other uses may also be possible. Exemplary materials that may be dewatered using the system 5 of FIG.5 include, without limitation, wastewater sludge and coal.
• the system 5 includes a feed hopper 10 for receiving and distributing a material (feedstock) of interest.
• the feed hopper 10 is located directly above a material receiving section 1 5 of the system 5.
• the feed hopper 10 may be offset from the receiving section 1 5 of the system 5, in which case a conveyor, chute or some other device may be interposed between the feed hopper and the system inlet to transfer the feedstock therebetween.
• a conveyor, chute or some other device may be interposed between the feed hopper and the system inlet to transfer the feedstock therebetween.
• other materials such as coagulants that may be useful in dewatering wastewater sludge, may also be added using the feed hopper.
• the feedstock material 80 is transferred from the receiving section 15 and transported through the system 5 by means of a vibratory conveyor 20, as described above.
• the vibratory conveyor 20 extends the full length of the system 5 - from the receiving section 15 through the microwave application chamber 25.
• at least the bottom of the conveying trough or table of the vibratory conveyor 20 includes a plurality of openings (e.g., perforations) through which water or another liquid contained within the feedstock may drain while being conveyed toward the microwave application chamber 25.
• this embodiment of the system 5 includes a drainage mechanism (e.g., dewatering grate) 30 that is located upstream of the microwave application chamber 25 and in a position over which the feedstock will be passed by the vibratory conveyor 20 prior to being irradiated. Consequently, at least some of the water or other liquid may drain from the feedstock through the vibratory conveyor trough or table and the underlying dewatering grate 30 prior to reaching the microwave application chamber 25.
• the draining liquid may pass into a liquid containment chamber 35 or a similar vessel located below the dewatering grate 30, from which it may be removed or allowed to flow through an exit port 40.
• the in-feed side end wall 45 of this embodiment of the microwave application chamber 25 projects down to a point near the top of the feedstock layer (bed) 80 being moved through the system 5.
• This design acts to prevent microwave energy from leaving the microwave application chamber 25 and entering the receiving section 1 5.
• a pin-choke bed 50 may be installed along the in-feed side of the microwave application chamber 25 as shown to similarly prevent the migration of stray microwave energy into the receiving section 15.
• a similar pin-choke bed 55 may be installed along the material discharge port 60 of the microwave application chamber 25 to prevent stray microwave energy from leaving the system 5.
• the material discharge port 60 extends vertically downward from the microwave application chamber 25, which saves space.
• material may be discharged from the microwave application chamber 25 into a cooling chamber or onto a discharge portion of the conveyor or another conveyor, which may extend substantially horizontally from the microwave application chamber.
• At least the walls of the microwave application chamber 25 are also preferably comprised of a material such as stainless steel that does not pass microwave energy, or are otherwise lined or coated to produce the same effect.
• the top of the receiving section 15 that leads to the microwave application chamber 25 may also be covered with a similar material for the same purpose.
• the microwave application chamber 25 is shown to be associated with microwave waveguides 65 that direct microwave energy from a microwave source (not shown) through corresponding entry points 70 in the overhead wall of the microwave application chamber 25.
• the waveguides 65 and entry points 70 may have other shapes, locations and orientations in other system embodiments.
• the waveguides 65 may be protected from reflected microwave energy by any of the techniques that would be well known to one of skill in the art.
• the exemplary system 5 shown in FIG. 5 also makes use of an optional fluidizing air flow that assists with drying the feedstock material 80 as it is simultaneously being heated and dried by microwave irradiation in the microwave application chamber 25. This feature may further reduce the liquid content of the material being dewatered or may reduce the required irradiation time.
• the system 5 includes a plenum 75 that resides below the vibratory conveyor 20 in the area underlying the microwave application chamber 25 and receives a supply of warm (preferably) air (or other gas) from a source thereof. The warm air passes through the openings in the conveying surface of the vibratory conveyor 20 and circulates through the feedstock material residing within the microwave application chamber 25.
• the fluidizing air may directly assist with drying of the feedstock material, which may eliminate the need for a ceramic tile surface along the vibratory conveyor conveying surface and may lessen the required microwave irradiation time.
• a vapor (e.g., steam) extraction apparatus may also be placed in communication with at least the microwave application chamber 25.
• a vapor extraction apparatus may be a part of the system 5 itself or may be a separate and remotely located apparatus that is connected to the microwave application chamber 25 and possibly other portions of the system by appropriate tubing, etc.
• such a vapor extraction apparatus may be useful to extract steam and or other vapors that may be generated as the feedstock material 80 is irradiated.
• the dewatered feedstock material 80 is discharged through the discharge port 60.
• the dewatered material may be collected in a collection hopper 85 or any number of other containers or collection means for removal and downstream handling and processing.
• the system 5 also includes a novel means for isolating the waveguides 65 from the vibratory effects of the vibratory conveyor 20. Vibratory isolation may be accomplished as described in U.S. Provisional Patent Application No. 61 /942, 183 filed on February 20, 2014.
• FIG. 6 Another exemplary microwave-based material processing system 100 is shown in FIG. 6. This particular embodiment is designed for use in a sterilizing operation, although other uses may also be possible.
• the system 100 of FIG. 6 is particularly well-suited to the sterilization of foodstuffs, although the sterilization of other materials is also certainly possible.
• the system 100 includes a feed hopper 105 for receiving and distributing a material (feedstock) of interest.
• the feed hopper 105 is located directly above a material receiving section 1 15 of the system 100.
• the feed hopper 105 may be offset from the receiving section 1 15 of the system 100, in which case a conveyor, chute or some other device may be interposed between the feed hopper and the system inlet to transfer the feedstock therebetween.
• the inlet section 1 15 of the system 100 may include a sealed inlet mechanism 120 that helps to create a gas-tight feedstock receiving chamber 125 within the system.
• the gas-tight feedstock receiving chamber 125 may be purged, preferably with an inert gas.
• the feedstock material 130 is transferred from the receiving section 1 15 and transported through the system 100 by means of a vibratory conveyor 135, as described above.
• the vibratory conveyor 135 extends the full length of the system 100 - from the receiving section 1 15 through the microwave application chamber 140 and discharge section 145.
• at least the bottom of the conveying trough or table of the vibratory conveyor 135 includes a plurality of openings (e.g., perforations).
• this embodiment of the system 100 also makes use of an optional fluidizing gas flow. More particularly, this exemplary embodiment includes the use of a fluidizing flow of inert gas that is passed through the plurality of openings in the bottom of the conveying trough or table of the vibratory conveyor 1 35 while the feedstock is transported through the microwave application chamber 140.
• the exemplary system 100 of FIG. 6 may further include a gas plenum 150 that resides below the vibratory conveyor 135 in the area underlying the microwave application chamber 140 to receive a supply of pressurized inert gas from a source thereof.
• the inert gas passes from the plenum through the openings in the conveying surface of the vibratory conveyor 135 and circulates through the feedstock material residing within the microwave application chamber 140.
• the effect of the fluidized flow of inert gas is to mix the feedstock, which allows for a more uniform absorption of microwave energy by the feedstock and may help to reduce the required irradiation time.
• the end walls 155, 1 60 of the microwave application chamber 140 project down to a point near the top of the feedstock layer (bed) 130 being moved through the system 100. This prevents microwave energy from leaving the microwave application chamber 140 and entering the adjacent receiving or discharge sections 1 15, 145 of the system 100. Additionally, a pin-choke bed 165, 170 may be installed along the in-feed and out-feed sides of the microwave application chamber 140 to similarly prevent the migration of stray microwave energy.
• At least the walls of the microwave application chamber 140 are also preferably comprised of a material such as stainless steel that does not pass microwave energy, or are otherwise lined or coated to produce the same effect.
• the top of the receiving section 1 15 that leads to the microwave application chamber 140 may also be covered with a similar material for the same purpose.
• the microwave application chamber 140 is shown to be associated with microwave waveguides 175 that direct microwave energy from a microwave source (not shown) through corresponding entry points 180 in the overhead wall of the microwave application chamber 140.
• the waveguides 1 75 and entry points 180 may have other shapes, locations and orientations in other system embodiments.
• the waveguides 1 75 may be protected from reflected microwave energy by any of the techniques that would be well known to one of skill in the art.
• the processed feedstock material 1 30 is discharged to the discharge section 145, which may comprise a cooling chamber.
• the sterilized material may be collected in a collection hopper 1 85 or any number of other containers or collection means for removal and downstream handling and processing.
• the outlet section 145 of the system 100 may include a sealed outlet mechanism 190 that helps to create a gas-tight discharge chamber 195.
• the discharge chamber 195 may also be purged, preferably with an inert gas.
• the system 1 00 also includes a novel means for isolating the waveguides 175 from the vibratory effects of the vibratory conveyor 135.
• the inlet seal 120 and/or outlet seal 190 may be similarly isolated. Vibratory isolation may be accomplished as described in U.S. Provisional Patent Application No. 61 /942, 183 filed on February 20, 2014.
• FIG. 7 Another exemplary microwave-based material processing system 200 is shown in FIG. 7.
• This particular embodiment also includes sorting/sifting functionality.
• This particular embodiment is well-suited to use in applications such as heating or drying materials such as industrial or building materials used in cement kilns or asphalt plants, for treating wastewater sludge, for remediating contaminated soils, and for the preparation of foodstuffs or coal. The processing of other materials is also certainly possible.
• the system 200 includes a feed hopper 205 for receiving and distributing a material (feedstock) of interest.
• the feed hopper 205 is located directly above a material receiving section 210 of the system 200.
• the feed hopper 205 may be offset from the receiving section 210 of the system 200, in which case a conveyor, chute or some other device may be interposed between the feed hopper and the system inlet to transfer the feedstock therebetween.
• the feedstock material 215 is transferred from the receiving section 21 0 and transported through the system 200 by means of a vibratory conveyor 220, as described above.
• the vibratory conveyor 220 extends the full length of the system 200 - from the receiving section 210 through the microwave application chamber 225 and discharge section 230.
• at least the bottom of the conveying trough or table of the vibratory conveyor 220 includes a plurality of openings (e.g., perforations) through which small deleterious or otherwise undesirable material may pass prior to passage of the feedstock through the microwave application chamber 225.
• the sorting/sifting functionality of this exemplary embodiment is provided by way of a sorting/sifting grate or screen 235 that is disposed in the conveying path of the feedstock material 215.
• the sorting/sifting grate or screen 235 is located upstream of the microwave application chamber 225 and in a position over which the feedstock 21 5 will be passed by the vibratory conveyor 220 prior to being irradiated. Consequently, smaller, deleterious or otherwise undesirable elements of the feedstock material 215 may be removed prior to microwave irradiation of the remaining, desirable portion of the feedstock material.
• the sorted/sifted material that passes through the sorting/sifting grate or screen 235 may be temporarily collected in a sorted/sifted material chamber 240 before being removed to another location.
• the in-feed end wall 245 of the microwave application chamber 225 projects down to a point near the top of the feedstock layer (bed) 215 being moved through the system 100. This prevents microwave energy from leaving the microwave application chamber 225 and entering the adjacent receiving section 210 of the system 200. Additionally, a pin-choke bed 250 may be installed along the in-feed side of the microwave application chamber 225 to similarly prevent the migration of stray microwave energy into the receiving section 210.
• a similar pin-choke bed 255 may be installed along the material discharge port 260 of the discharge section 230 of the system 200 to prevent stray microwave energy from leaving the system.
• the material discharge port 260 extends vertically downward from the terminus of the discharge section 230.
• the discharge side pin- choke bed 255 may instead be installed above the feedstock bed along the out- feed side of the microwave application chamber 225.
• At least the walls of the microwave application chamber 225 are also preferably comprised of a material such as stainless steel that does not pass microwave energy, or are otherwise lined or coated to produce the same effect.
• the top of the receiving section 215 that leads to the microwave application chamber 225 may also be covered with a similar material for the same purpose.
• the microwave application chamber 225 is shown to be associated with microwave waveguides 265 that direct microwave energy from a microwave source (not shown) through corresponding entry points 270 in the overhead wall of the microwave application chamber 225.
• the waveguides 265 and entry points 270 may have other shapes, locations and orientations in other system embodiments.
• the waveguides 265 may be protected from reflected microwave energy by any of the techniques that would be well known to one of skill in the art.
• the processed feedstock material 21 5 is discharged to the discharge section 230, which may comprise a cooling chamber.
• the processed material may be collected in a collection hopper 275 or any number of other containers or collection means for removal and downstream handling and processing.
• the sorted/sifted material may also be discharged from the sorted/sifted material chamber 240 and collected in a collection hopper 280 or a similar container, which may be independent from or a separate portion of the collection hopper 275 in which the processed material is collected.
• the system 200 also includes a novel means for isolating the waveguides 265 from the vibratory effects of the vibratory conveyor 220. Vibratory isolation may be accomplished as described in U.S. Provisional Patent Application No. 61 /942,183 filed on February 20, 2014.
• FIG. 8 Yet another exemplary microwave-based material processing system 300 is shown in FIG. 8. This particular embodiment is designed for use in a drying application, although other uses may also be possible. Exemplary materials that may be processed using the system 300 of FIG. 8 include, without limitation, wastewater sludge, contaminated soils, coal and foodstuffs.
• the system 300 includes a feed hopper 305 for receiving and distributing a material (feedstock) of interest.
• the feed hopper 305 is located directly above a material receiving section 310 of the system 300.
• the feed hopper 305 may be offset from the receiving section 310 of the system 300, in which case a conveyor, chute or some other device may be interposed between the feed hopper and the system inlet to transfer the feedstock therebetween.
• the feedstock material 315 is transferred from the receiving section 305 and transported through the system 300 by means of a vibratory conveyor 320, as described above.
• the vibratory conveyor 320 extends the full length of the system 300 - from the receiving section 310 through the microwave application chamber 325.
• at least the bottom of the conveying trough or table of the vibratory conveyor 320 includes a plurality of openings (e.g., perforations) through which warm air (or another gas) may be passed while the feedstock passes through the system 300.
• this embodiment of the system 300 makes use of a fluidizing air flow. Unlike the previously described exemplary embodiments, wherein the fluidizing bed resides only below the microwave application chamber, the fluidized bed 330 of this exemplary embodiment extends along substantially the entire length of the system. This feature helps to dry the feedstock 315, thereby reducing the required irradiation time.
• the system 300 includes an air plenum 335 that resides below the vibratory conveyor 320 and receives a supply of a warmed air from a source thereof. The warm air passes through the openings in the conveying surface of the vibratory conveyor 320 and circulates through the feedstock material as it is conveyed through the system 300.
• the end walls 340, 345 of this embodiment of the microwave application chamber 325 projects down to a point near the top of the feedstock layer (bed) 315 being moved through the system 300.
• This design acts to prevent microwave energy from leaving the microwave application chamber 325 and entering the receiving section 310.
• a pin-choke bed 350 may be installed along the in-feed side of the microwave application chamber 310 as shown to similarly prevent the migration of stray microwave energy into the receiving section 310.
• a similar pin-choke bed 355 may be installed along the material discharge port 360 of the microwave application chamber 325 to prevent stray microwave energy from leaving the system 300.
• the material discharge port 360 extends vertically downward from a discharge section 365, which may be a cooling chamber.
• At least the walls of the microwave application chamber 325 are also preferably comprised of a material such as stainless steel that does not pass microwave energy, or are otherwise lined or coated to produce the same effect.
• the top of the receiving section 310 that leads to the microwave application chamber 325 may also be covered with a similar material for the same purpose.
• the microwave application chamber 325 is shown to be associated with microwave waveguides 365 that direct microwave energy from a microwave source (not shown) through corresponding entry points 370 in the overhead wall of the microwave application chamber 325.
• the waveguides 365 and entry points 370 may have other shapes, locations and orientations in other system embodiments.
• the waveguides 365 may be protected from reflected microwave energy by any of the techniques that would be well known to one of skill in the art.
• the feedstock material 315 is discharged through the discharge port 360.
• the dried material may be collected in a collection hopper 375 or any number of other containers or collection means for removal and downstream handling and processing.
• the system 300 also includes a novel means for isolating the waveguides 365 from the vibratory effects of the vibratory conveyor 320. Vibratory isolation may be accomplished as described in U.S. Provisional Patent Application No. 61 /942,183 filed on February 20, 2014.
• the microwave energy may be transmitted to the microwave application chamber via bifurcated waveguides, such that the microwaves enter the microwave application chamber in parallel alignment and at a frequency between approximately 894 MHz and approximately 1 ,000 MHz.
• the microwave energy may be directed at the feedstock from above the vibratory conveyor and possibly also transversely thereto. In either case, it is contemplated that the microwave energy will be directed at an angle that is substantially perpendicular to the direction of travel of the feedstock.
• the conveying surface of the vibratory conveyor upon which the feedstock material rests and moves may be optionally provided with one or more ramps or similar features along its length.
• the ramps act to further mix the feedstock material by causing a tumbling thereof as the material falls from one ramp to the next or from a ramp to a flat portion of the vibratory conveying surface.
• the ramps also have the effect of variably altering the distance of the feedstock material from the entry points and reflection points of the microwave energy within the microwave application chamber as the feedstock material moves therethrough.
• the exemplary system embodiments may also be provided with one or more directing channels or other guideways that function to cause a movement of the material of interest in a direction other than the normal conveying direction. More specifically, the material directing channels are sized and oriented to cause at least a portion of the material of interest to move transversely (e.g., laterally or diagonally) to the normal conveying direction as the material moves through the microwave application section. The effect of this transverse movement is to further mix the material of interest so as to promote a more uniform absorption of microwave energy thereby.
• Such material directing channels or other guideways may be located in/on the conveying surface of the vibratory conveyor of the given system.
• the material directing channels may be located to pass over the conveying surface of the ramps, or the material directing channels may be arranged to avoid the ramps.
• microwave-based treatment systems employing a microwave energy containment device according to the invention may be used for the microwave heating and treatment of various materials.
• a material of interest is heated to elevate its temperature by subjecting the material to microwave irradiation.
• the irradiation process may occur in an oxygen-containing environment or in an inert and substantially oxygen free environment.
• One example of such a heating embodiment is a dewatering embodiment, wherein a material to be dewatered may be subjected to microwave irradiation for the purpose of removing some amount of water therefrom.
• a pre-irradiation dewatering grate or another similar mechanism(s) may be employed upstream of the microwave applicator portion of the associated system to assist with dewatering.
• a material that is well-suited to dewatering by microwave irradiation is wastewater sludge. In such an application, water is removed from the wet sludge material by microwave heating to produce a processed sludge that is sufficiently dried and sterilized for landfill deposit or a dewatered cake that is sufficiently dry for incineration.
• Microwave processing of wastewater sludge may also provide the benefit of eradicating bacteria or other objectionable sludge ingredients, possibly rendering the sludge acceptable for use as a fertilizer or otherwise sufficiently innocuous for alternative disposal methods.
• a dewatering system and method embodiment may also be well-suited for removing moisture from coal prior to its pulverization and/or burning as a fuel.
• Another exemplary embodiment is a sterilization embodiment, wherein a material to be sterilized is subjected to microwave irradiation in an inert and substantially oxygen free environment and its temperature is raised to a point sufficient to eliminate certain possible contaminants, bacteria, etc.
• a material that is well-suited to sterilization by microwave irradiation is a foodstuff.
• Another exemplary embodiment is a sorting/sifting embodiment, wherein a material to be heated or dried may be sorted/sifted prior to being subjected to and heated by microwave irradiation.
• the material of interest may pass over a sorting/sifting grate or screen while being conveyed to a microwave applicator portion of the system. This allows smaller, deleterious or otherwise undesirable elements of the material of interest to be removed prior to microwave irradiation of the remaining, desirable portion of the material of interest.
• the sorted/sifted material may be routed to another location, may be collected separately from the irradiated material of interest, etc.
• Non-limiting examples of such system and method embodiments of the invention may find use in cement kilns and asphalt plants, in the treatment of wastewater sludge, in the remediation of contaminated soils, and in processes for preparing coal or sterilizing foodstuffs.
• Another exemplary embodiment is directed to the drying of a material of interest with the additional use of a fluidized bed.
• the conveyor by which the material is transported through the system, or at least through the microwave applicator section thereof, is part of a fluidized bed by which warm air from a heat source is directed through the underside of the conveyor to assist with drying.
• a plenum may be provided below the conveyor to receive and distribute the warm air through the conveyor.
• Non-limiting examples of such system and method embodiments of the invention may find use in the treatment of wastewater sludge, in the remediation of contaminated soils, and in processes for preparing coal or sterilizing foodstuffs.
• the feedstock material may be a carbonaceous material such as scrap vehicle tires.
• Exemplary systems of the invention may be used to convert scrap vehicle tires into useful products such as, for example, gaseous and liquid fuels, and commodity products such as carbon black and activated carbon.
• pulverized tire material may be provided to the system and passed through a microwave application chamber, where the material is converted by microwave irradiation. Microwave irradiation may occur in a gas-tight environment, and the various byproducts of the irradiation process may be collected.
• An exemplary microwave-based material processing system embodiment will generally have a material receiving section, which may or may not include a feed hopper or a comparable device for controllably distributing a feedstock in the form of a material of interest.
• the material being processed may be delivered into a gas-tight receiving/processing section of the system that is purged with a gas, preferably an inert gas.
• the material receiving section of the system may not be gas tight and may be non-purged.
• the receiving section of an exemplary system may be open to the atmosphere, whereby material to be processed may be deposited directly onto an exposed conveyor belt, a receiving portion of the vibratory conveyor, or some other material infeed mechanism.
• the treated material After being sufficiently irradiated to result in satisfactory heating, dewatering, drying, sterilization, conversion, etc., of the material being processed, the treated material may in some embodiments be moved into a cooling section of the system. In other cases, a system cooling section and an associated cooling process may be omitted. In any case, the processed material is eventually discharged from the system, such as by being conveyed to a discharge section and deposited into collection vessels, etc. Liquid and/or gaseous byproducts of conversion may also be removed from certain embodiments of the system at various times and locations.
• FIGS. 9-1 For purposes of further description, various exemplary embodiments of microwave-based material processing systems according to the invention are depicted in FIGS. 9-1 3. While various conveyance devices may be used to transport a material to be processed, each of the exemplary embodiments shown in FIGS. 9-13 and described below employ a vibratory conveyor to transport the material being processed (i.e., the feedstock) through the system, or at least through a microwave applicator portion of the system.
• the vibratory conveyors of the embodiments shown in FIGS. 9-13 each have a vibratory drive system that is in motive communication with a material-carrying portion (e.g., a conveying trough or table) upon which the feedstock material rests and moves.
• a material-carrying portion e.g., a conveying trough or table
• the vibratory drive system may reside beneath the material-carrying portion or in a location other than beneath the material-carrying portion in different system embodiments.
• the vibratory drive system may include one or more vibratory motors for initiating and sustaining the driving motion of the conveyor, but embodiments of the invention are not limited to any particular vibratory drive system design. In any case, the vibratory drive system is normally operative to produce the overall vibrating motion that induces movement of the feedstock.
• a variable frequency drive is also preferably used to control the vibratory conveyor so as to allow for a wide range of possible conveying speeds. Both very fast and very slow transport speeds are achievable, as is virtually any speed in between, and material transport programs comprising a combination of various material transport speeds may be employed. It is also possible to produce both a gentle forward motion of the material or a more abrupt and severe jump forward. Furthermore, use of the vibratory conveyor and its associated variable frequency drive allows the feedstock material of interest to be mixed by vibration while being transported through the system, or to be mixed by vibration while held in a stationary position. Such mixing promotes a more even heating of the material from the top to the bottom of the material layer.
• FIG. 9 A first exemplary embodiment of a microwave-based material processing system 5 employing a pass-through microwave energy containment device is generally shown in FIG. 9. This particular embodiment is designed for use in a dewatering application, although other uses may also be possible. Exemplary materials that may be dewatered using the system 5 of FIG.9 include, without limitation, wastewater sludge and coal. A more detailed description of an exemplary dewatering embodiment is presented in U.S. provisional Application No. 62/042,289 filed on August 27, 2014.
• the system 5 includes a feed hopper apparatus 10 for receiving and distributing a material (feedstock) of interest. If desired, other materials such as coagulants that may be useful in dewatering wastewater sludge, may also be added using the feed hopper.
• the feedstock material 70 is delivered to a receiving section 15 and subsequently transferred from the receiving section and through the system 5 by means of a vibratory conveyor 20, as generally described above.
• a vibratory conveyor 20 at least the bottom of the conveying trough or table of the vibratory conveyor 20 includes a plurality of openings (e.g., perforations) through which water or another liquid contained within the feedstock may drain while being conveyed toward the microwave application chamber 25.
• a drainage mechanism (e.g., dewatering grate) 30 is located upstream of the microwave application chamber 25 and in a position over which the feedstock will be passed by the vibratory conveyor 20 prior to being irradiated.
• the draining liquid may be removed or allowed to flow through an exit port 40 located subjacent to the dewatering grate 30.
• the microwave application chamber 25 is shown to be associated with microwave waveguides 35 that direct microwave energy from a microwave source (not shown) through corresponding entry points (e.g., windows) 40 in the overhead wall of the microwave application chamber 25.
• This particular exemplary system 5 also makes use of an optional fluidizing air flow 45 that assists with drying the feedstock material 70 as it is simultaneously being heated and dried by microwave irradiation in the microwave application chamber 25. This feature may further reduce the liquid content of the material being dewatered or may reduce the required irradiation time.
• a vapor (e.g., steam) extraction apparatus may also be placed in communication with at least the microwave application chamber 25 to extract steam and or other vapors that may be generated as the feedstock material 70 is irradiated.
• the dewatered material is removed from the system.
• the dewatered material is discharged from the downstream end of the microwave application chamber 25 through a discharge port 50, whereafter it drops into a material hopper 55.
• a first pass-through microwave energy containment device 60 is associated with a portion of the feed hopper 10 to prevent microwave energy from migrating from the microwave application chamber 25 and leaving the receiving section 15 of the system.
• a second pass-through microwave energy containment device 65 is associated with the discharge port 50 of the microwave application chamber 25 to prevent stray microwave energy from leaving the system 5 through the discharge port.
• Each of the first and second pass-through microwave energy containment devices 60, 65 may be designed and constructed as generally described above and/or as shown in more detail in FIGS. 14A-14B and 15A- 15B. That is, the pass-through microwave energy containment devices 60, 65 are provided in the form of microwave energy-blocking baffles comprising a bundle or array of tubes of some predetermined cross-sectional dimension (e.g., diameter) and length. The dimensions of the individual tubes are selected so as to prevent the passage therethrough of the wavelength of microwave energy introduced into the microwave application chamber through the waveguides 35 and entry points 40. Alternatively, it may be possible to use a single microwave blocking tube in certain embodiments.
• the pass-through microwave energy containment devices 60, 65 operate to block the unwanted migration of stray microwave energy while simultaneously allowing feedstock 70 material or processed material to pass therethrough.
• feedstock material may pass through the device 60 and into the receiving section 1 5 of the system 5 regardless of whether an irradiation process is ongoing within the microwave application chamber 25.
• processed material may be discharged through the device 65 and into the material hopper 55 regardless of whether an irradiation process is ongoing within the microwave application chamber 25. Consequently, without the need to periodically shut off the microwave energy source, feedstock material 70 may be continuously fed into and processed by the system 5 - without any leakage of stray microwave energy and without the need for pin-choke beds or other known microwave energy blocking devices.
• FIG. 10 Another exemplary microwave-based material processing system 100 employing a pass-through microwave energy containment device is shown in FIG. 10. This particular embodiment is designed for use in a sterilizing operation, including but not limited to the sterilization of foodstuffs.
• the system 100 includes a feed hopper apparatus 105 for receiving and distributing a material (feedstock) of interest.
• the feedstock material 180 is delivered to a receiving section 1 1 0 of the system 100 and subsequently transferred from the receiving section and through the system 100 by means of a vibratory conveyor 1 15, as generally described above.
• the system 100 may be purged, such as with an inert gas, to assist with sterilization.
• both the inlet section 1 10 and outlet section 120 of the system 100 may include a sealing mechanism 1 25, 130 that helps to create a gas-tight feedstock receiving chamber 125 within the system.
• a novel vibratory isolation device 175 is used in this embodiment to isolate the outlet sealing mechanism 130 from the vibratory effects of the vibratory conveyor 1 15.
• One embodiment of such a vibratory isolator is described in U.S. Provisional Patent Application No. 61 /942,183 filed on February 20, 2014.
• the system 100 again includes a microwave application chamber 135, which is again shown to be associated with microwave waveguides 140 that direct microwave energy from a microwave source (not shown) through corresponding entry points 145 in the overhead wall of the microwave application chamber 135.
• this particular embodiment of the system 100 also makes use of an optional fluidizing flow of inert gas 1 50 that is passed through a plurality of openings in the bottom of the conveying trough or table of the vibratory conveyor 1 15 while the feedstock 180 is transported through the microwave application chamber 1 35.
• the processed material 1 80 is removed from the system.
• the sterilized material is discharged from the downstream end of the microwave application chamber 135 through a discharge port 155, whereafter it drops into a material hopper 160.
• a first pass-through microwave energy containment device 1 65 is associated with a portion of the feed hopper 105 to prevent microwave energy from migrating from the microwave application chamber 135 and exiting the receiving section 1 10.
• a second pass- through microwave energy containment device 170 is associated with the discharge port 155 of the microwave application chamber 1 35 to prevent stray microwave energy from leaving the system 1 00 through the discharge port.
• the design, construction and function of the pass-through microwave energy containment devices 165, 170 may be as described above and/or as shown in FIGS. 14A-14B and 15A-15B.
• FIG. 1 1 Another exemplary microwave-based material processing system 200 employing a pass-through microwave energy containment device is shown in FIG. 1 1 .
• This particular embodiment also includes sorting/sifting functionality.
• the system 200 includes a feed hopper apparatus 205 for receiving and distributing a material (feedstock) of interest.
• the feedstock material 270 is delivered to a receiving section 21 0 of the system 200 and subsequently transferred from the receiving section and through the system 200 by means of a vibratory conveyor 215, as generally described above.
• the sorting/sifting functionality of this exemplary embodiment is provided by way of a sorting/sifting grate or screen 220 that is disposed in the conveying path of the feedstock material 270.
• the sorting/sifting grate 220 separates smaller, deleterious or otherwise undesirable elements of the feedstock material 270 such that only a desirable portion of the feedstock material is irradiated.
• the system 200 again includes a microwave application chamber 225, which is associated with microwave waveguides 230 that direct microwave energy from a microwave source (not shown) through corresponding entry points 235 in the overhead wall of the microwave application chamber 225.
• the processed material is removed from the system.
• the processed material 270 is discharged from the downstream end of the microwave application chamber 225 through a discharge port 240, whereafter it drops into a material hopper 245.
• the sorted/sifted material may also be discharged from a sorted/sifted material chamber 250 of the system 200 and collected in a separate collection hopper 255 or a similar container.
• a first pass-through microwave energy containment device 260 is associated with a portion of the feed hopper 205 to prevent microwave energy from migrating from the microwave application chamber 225 and exiting the receiving section 210.
• a second pass- through microwave energy containment device 265 is associated with the discharge port 240 of the microwave application chamber 225 to prevent stray microwave energy from leaving the system 200 through the discharge port.
• the design, construction and function of the pass-through microwave energy containment devices 260, 265 may be as described above and/or shown in FIGS. 14A-14B and 15A-15B.
• FIG. 12 Another exemplary microwave-based material processing system 300 employing a pass-through microwave energy containment device is shown in FIG. 12. This particular embodiment is designed for use in a drying application, although other uses may also be possible.
• the system 300 includes a feed hopper apparatus 305 for receiving and distributing a material (feedstock) of interest.
• the feedstock material 365 is delivered to a receiving section 31 0 of the system 300 and subsequently transferred from the receiving section and through the system 300 by means of a vibratory conveyor 315, as generally described above.
• this embodiment of the system 300 makes use of a fluidizing air flow 320, which is distributed to the feedstock material 365 by a fluidizing bed 325 that extends along substantially the entire length of the system. This feature helps to dry the feedstock 365, thereby reducing the required irradiation time.
• the system 300 again includes a microwave application chamber 330, which is associated with microwave waveguides 335 that direct microwave energy from a microwave source (not shown) through corresponding entry points 340 in the overhead wall of the microwave application chamber 330.
• a microwave source not shown
• the processed material is removed from the system.
• the dried material 365 is discharged from the downstream end of the microwave application chamber 330 through a discharge port 345, whereafter it drops into a material hopper 350.
• a first pass-through microwave energy containment device 355 is associated with a portion of the feed hopper 305 to prevent microwave energy from migrating from the microwave application chamber 330 and exiting the receiving section 310.
• a second pass- through microwave energy containment device 360 is associated with the discharge port 345 of the microwave application chamber 330 to prevent stray microwave energy from leaving the system 300 through the discharge port.
• the design, construction and function of the pass-through microwave energy containment devices 355, 360 may be as described above and/or shown in FIGS. 14A-14B and 15A-15B.
• FIG. 13 Yet another exemplary microwave-based material processing system 400 employing a pass-through microwave energy containment device is shown in FIG. 13.
• This particular embodiment is ideally designed for the microwave conversion of scrap tires.
• the system 400 may also be used to process other materials, such as without limitation, waste rubber from other products or manufacturing processes, waste plastics and polymers, asphalt shingles, e-waste, medical waste, municipal sludge, oil/shale drilling waste, coal (e.g., for gasification), and foodstuffs, and may also serve a role in systems and processes for producing activated carbon.
• this particular embodiment includes a feed hopper 405 for receiving and distributing a material (feedstock) of interest.
• the feedstock material 490 is delivered to a receiving section 41 0 of the system 400 and subsequently transferred from the receiving section and through the system 400 by means of a vibratory conveyor 415, as generally described above.
• both the inlet section 410 and an outlet section 420 of the system 5 may include a sealing mechanism 425, 430.
• the gas-tight may be purged, preferably with an inert gas.
• a microwave application chamber 435 is present and is shown to include microwave waveguides 440 that direct microwave energy from a microwave source (not shown) through corresponding entry points 445 in the overhead wall of the microwave application chamber 435.
• a plurality of gas ports 450 may also be provided to vent gaseous byproducts of the microwave irradiation process from the microwave application chamber.
• the processed tire material may be transferred by the vibratory conveyor to a cooling chamber 455 where the material is allowed to cool sufficiently before being removed through a discharge port 460 therein.
• the processed tire material may be discharged directly from the microwave application chamber 435 to an external cooling apparatus, (not shown).
• the processed tire material 465 may be discharged into a material hopper 470, as shown.
• the system 400 may include a novel means for isolating various system components from the vibratory effects of the vibratory conveyor 415.
• the waveguides 440 of the microwave applicator and or the sealing mechanisms 425, 430 may be isolated by such vibration isolators 475.
• a first pass-through microwave energy containment device 480 is associated with a portion of the feed hopper 405 to prevent microwave energy from migrating from the microwave application chamber 435 and exiting the receiving section 410.
• a second pass- through microwave energy containment device 485 is associated with the discharge port 460 of the system 400 to prevent stray microwave energy from leaving the system through the discharge port.
• the design, construction and function of the pass-through microwave energy containment devices 480, 485 may be as described above and/or shown in FIGS. 14A-14B and 1 5A-15B.
• FIGS. 14A-14B shown are a side view and a front view of one exemplary embodiment of a pass-through microwave energy containment device 500 as used in the exemplary system embodiments of FIGS. 9-13.
• this pass-through microwave energy containment device 500 includes a substantially hollow housing 505 having an open top 51 0 end and an open bottom end 51 5. Located within the housing 505 and between the top and bottom ends is a bundle or array 520 of tubes 525.
• the housing 505 may be the same length as the tubes 525, or may be longer than the tubes 525 as shown.
• the cross-sectional dimension and length of the tubes 525 is dependent on the frequency of the microwave energy to be blocked.
• the internal cross-sectional dimension of each tube 525 should be less than half the wavelength of the microwave energy to be blocked, and the length of each tube should be greater than twice the maximum cross-sectional dimension.
• the length of each tube 525 should be at least four times its maximum cross-sectional dimension. Consequently, in an exemplary pass- through microwave energy containment device 500 designed to block microwave energy having a frequency of 915 MHz, the maximum square or round cross-sectional dimension of each tube should be about 3 inches and the maximum length of each tube should be between about 6 inches.
• each tube 525, and the overall cross- sectional shape of the tube array 520 may vary.
• the cross-sectional shape of each tube 525 of the array 520 may be round (FIG. 15A) or square (FIG. 15B).
• Other shapes are also possible, within the constraints of the aforementioned dimensional relationships.
• the cross-sectional shape of the tube array 520 may also vary, within the constraints of properly housing the tubes 525 and fitting into the appropriate port, pipe, conduit, etc., of a given microwave-based material processing system.
• such a pass-through microwave energy containment device is able to advantageously block the unwanted migration of stray microwave energy while simultaneously allowing feedstock material or processed material to pass therethrough. Consequently, without the need to periodically shut off the microwave energy source, feedstock material may be continuously fed into and processed by a system that employs such a device(s), without any leakage of stray microwave energy and without the need for pin-choke beds or other known microwave energy blocking devices. It may be alternatively or also possible to place pass-through microwave energy containment devices at other locations in certain microwave- based material processing systems.
• microwave energy may be transmitted to the microwave application chamber at a frequency between approximately 894 MHz and approximately 1 ,000 MHz, for example, at 915MHz.
• the microwave energy may be directed at the feedstock from above the vibratory conveyor and possibly also transversely thereto. In either case, it is contemplated that the microwave energy will be directed at an angle that is substantially perpendicular to the direction of travel of the feedstock.
• the conveying surface of the vibratory conveyor upon which the feedstock material rests and moves may be optionally provided with one or more ramps or similar features along its length.
• the ramps act to further mix the feedstock material by causing a tumbling thereof as the material falls from one ramp to the next or from a ramp to a flat portion of the vibratory conveying surface.
• the ramps also have the effect of variably altering the distance of the feedstock material from the entry points and reflection points of the microwave energy within the microwave application chamber as the feedstock material moves therethrough.
• the exemplary system embodiments may also be provided with one or more directing channels or other guideways that function to cause a movement of the material of interest in a direction other than the normal conveying direction. More specifically, the material directing channels are sized and oriented to cause at least a portion of the material of interest to move transversely (e.g., laterally or diagonally) to the normal conveying direction as the material moves through the microwave application section. The effect of this transverse movement is to further mix the material of interest so as to promote a more uniform absorption of microwave energy thereby.
• Such material directing channels or other guideways may be located in/on the conveying surface of the vibratory conveyor of the given system.
• the material directing channels may be located to pass over the conveying surface of the ramps, or the material directing channels may be arranged to avoid the ramps.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Processing Of Solid Wastes (AREA)
• Apparatus For Disinfection Or Sterilisation (AREA)

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• 2015
  • 2015-10-06 EP EP15848746.2A patent/EP3205181A4/de not_active Withdrawn
  • 2015-10-06 WO PCT/US2015/054334 patent/WO2016057581A1/en active Application Filing

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