Systems and methods for the thermochemical production and purification of hydrocarbon compounds - Patents.com

Abstract

A system is provided that allows for a continuous process involving the introduction of particles into a reactor drum having a low oxygen environment. Heavy hydrocarbons are boiled off from the particles during heating of the particles. The boiled off heavy hydrocarbons mix with a heated gas stream that heats the particles in the reactor drum. The heated gas stream (with the boiled off heavy hydrocarbons) exits the drum and is recycled back to the heat source to reheat the gas stream prior to re-entering the reactor drum. Repeated exposure to high temperatures within the reactor drum breaks down the heavy hydrocarbons into lighter hydrocarbons. The lighter hydrocarbons can then be separated out of the heated gas stream and collected for sale or use.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This patent application claims priority to U.S. Patent Application No. 63 / 311,220, filed February 17, 2022, the entire disclosure of which is incorporated herein by reference for all purposes.

[0002] (Technical field) The present disclosure relates generally to pyrolysis, torrefaction, and / or gasification systems and methods, and more specifically to the production of gas and liquid hydrocarbon products via biomass pyrolysis, torrefaction, and gasification systems and methods. [Background technology]

[0003] Torrefaction / pyrolysis / gasification of biomass particles is well known and is a process in which biomass and / or other organic particles are heated in a low-oxygen environment. This causes volatile compounds within the particles to be boiled off and the cellular structure of the particles to break down, resulting in a partial loss of mass and an increase in friability. Torrefaction / pyrolysis / gasification causes reactions within the remaining cellular structure that improve the moisture resistance of the resulting product. The particles remaining after undergoing the torrefaction / pyrolysis / gasification process have an improved energy value, measured in terms of heat energy per unit weight. The extent of torrefaction / pyrolysis / gasification of biomass and / or other organic particles depends on several factors, including the composition, the level of heat applied, the length of time the heat is applied, and the ambient gas conditions (especially relative to the oxygen level).

[0004] Current torrefaction / pyrolysis / gasification systems remove / liberate volatiles (sometimes referred to as tars) in the gas phase from feedstock particles input into the system as part of the process to produce torrefied particles. These volatiles are typically treated as waste / by-products that must be disposed of as part of the torrefaction / pyrolysis / gasification process. The production, capture, and disposal of these tars reduces the efficiency of the torrefaction / pyrolysis / gasification system. Summary of the Invention [Means for solving the problem]

[0005] The embodiments described herein provide systems and methods that are particularly well suited for torrefaction of various sized organic particles (including, in particular, cellulosic biomass particles) in an efficient and consistent manner while simultaneously refining the removed volatiles into by-products that can be collected instead of or in addition to the torrefied organic particles. The systems and methods are readily scalable to meet the needs of a wide variety of industries, and provide improved process control for monitoring and adjusting operating parameters to optimize or tailor the properties of the resulting torrefied / pyrolyzed / gasified biomass particles, the purified volatiles, or both.

[0006] Torrefaction, gasification, and pyrolysis (TGP) reactions are similar in nature and are differentiated primarily by the range of temperatures at which the reactions are carried out. For purposes of this disclosure, TGP reactions broadly include the thermochemical decomposition of organic compounds in a manner in which oxidants are controlled or entirely eliminated. For purposes of this disclosure, use of the terms "torrefaction," "pyrolysis," and "gasification" are understood to be interchangeable unless specifically stated otherwise.

[0007] Thermochemical bio-oil includes a range of hydrocarbon products produced from the thermochemical processing of biologically generated organic material. Thermochemical processing produces hydrocarbon compounds typically derived from fossil fuels. Examples include crude oil, jet fuel, gasoline, alcohol, diesel, solvents, polymers, alkanes, alkenes, alkadienes, aromatics, carboxylic acids, and many other organic compounds.

[0008] Pyrolysis is a process that utilizes heat and / or pressure to break larger, heavier hydrocarbon molecules into smaller, lighter molecules. Pyrolysis, as used herein, refers to the decomposition of hydrocarbon compounds. Pyrolysis can result from a TGP reaction (e.g., in the systems disclosed herein). Catalytic cracking is another process that refines hydrocarbon molecules. Catalytic cracking uses a catalyst to facilitate the breaking of larger, heavier hydrocarbon molecules into smaller, lighter molecules. The catalyst can allow for the modification of reaction temperature, pressure, ratio and type of compounds generated, or any combination thereof.

[0009] According to one embodiment, a TGP system may be summarized as including an inlet for receiving particles (e.g., biomass particles), a reactor drum rotatable about its longitudinal axis, a heat source upstream of the reactor drum for heating gas contained within the system to a temperature sufficient to initiate and sustain a TGP reaction of the particles in the reactor drum during operation of the system, a fan device for generating a flow of heated gas through the reactor drum that is sufficient to sustain a TGP reaction of the particles in the reactor drum along the length of the reactor drum such that the particles interact with the heated gas flow as the reactor drum rotates when the system is in operation, and a gas duct coupled to at least the reactor drum, the heat source, and the fan device for recirculating a portion of the gas or gases exiting the reactor drum back to the heat source and reheating the gas for reintroduction into the reactor drum.

[0010] The heated gas stream directly heats the particles as the gas stream circulates through the reactor drum. As the particles are heated, compounds in the particles can be thermochemically decomposed (e.g., into compounds including elemental, organic, hydrocarbon compounds / mixtures, or any combination thereof, which can be in the form of one or more of gas, water vapor, and aerosol) via the TGP reaction in the reactor. These gas mixtures are commonly referred to as synthesis gas or syngas. Heating the particles can produce an amount of syngas in excess of that required to circulate through the system and sustain the TGP reaction in the reactor drum.

[0011] The reactor drum may be configured to regulate the movement of particles through the reactor drum, thereby affecting the residence time of the particles within the reactor drum. The reactor drum may include features that interact with the heated syngas stream and sort particles according to particle density, particle size, or both (e.g., by moving relatively denser particles more slowly through the reactor drum compared to particles of similar size, by moving relatively larger particles more slowly through the reactor drum compared to particles having similar density, etc.).

[0012] The TGP system may further include a hopper located downstream of the reactor drum to collect solid particles exiting the reactor drum and discharge the solid particles from the system. The system may further include ducting at various locations to remove and / or introduce gases into the system. The ducting may include control valves and dampers positioned to regulate pressure levels within the system and allow gas phase elements and / or compounds to enter and / or exit the system while preventing oxygen ingress.

[0013] Ducting may route the gas from the system to a remote device or devices for use of the exhaust gas in an auxiliary or complementary process. The remote device or devices may include, for example, systems and methods for sequestration, separation, collection, or any combination thereof, of components from the routed gas. Examples of remote devices may include condensers, separators, quenchers, purifiers, compressors, expanders, or any combination thereof. The remote device may include a heat source, such as a combustion system that utilizes a portion of the routed gas (either in its entirety or as selected components thereof) to generate heat, which may then be fed into the gas stream on its way to the reactor drum (e.g., via a heat exchanger).

[0014] The system may further include at least one airlock located between the inlet and the reactor drum to limit the amount of oxygen entering the system when receiving the particles. The system may further include at least one sealing mechanism between the reactor drum and an adjacent structure. The sealing mechanism may maintain separation of the contents of the reactor drum and the surrounding atmosphere. The TGP system may include a mechanism coupled to an inert or semi-inert gas or vapor source for selective purging of the reactor drum (e.g., during start-up or shutdown operations) to maintain an oxygen-free environment within the reactor drum.

[0015] According to one embodiment, the system can be calibrated such that gases, water vapor, and / or compounds (e.g., hydrocarbons) generated from the TGP reaction are contained within the system at elevated temperatures (e.g., from about 220° F. to about 1,250° F.) for a period of time that exceeds the solid particles, e.g., from about 110% to about 1,000% of the time it takes for the solid particles to transition the length of the reactor drum.

[0016] The system may be constructed such that the circulating gas mixture passes through the gas circulation loop multiple times. The loop may include a hot area within the system. The hot area may include a reactor drum, an area including or adjacent to a heating element, an area including or adjacent to a combustion element, an area including or adjacent to a heated bed material, an area including or adjacent to a heat exchanger, or any combination thereof to facilitate purification of the gas mixture (e.g., pyrolysis of heavy hydrocarbons). The hot area may serve as a primary method of increasing the temperature of the gas within the loop. The system may include, for example, an electric heater, a heated bed material, a heat exchanger, direct combustion of materials within the loop, or any combination thereof. The system may also be constructed such that the hot zone is separate / independent from heating of the particles within the reactor drum. For example, the system may include a flash / reflux drum, a high temperature pyrolyzer, a packed column, or any combination thereof.

[0017] According to one embodiment, the system may include temperature differentials along the loop that separate certain components (e.g., hydrocarbon compounds) from the rest of the circulating gas mixture. Separation may occur via phase change behavior (e.g., distillation and condensation of individual hydrocarbon compounds). Localized separation of the hydrocarbon compounds allows for selective removal of these compounds from the system. The system may include components that permanently remove the compounds from the loop and direct the compounds for further processing or use in other processes of the system. The system may also include components that reintroduce the compounds into the loop after further processing or at a different location in the system.

[0018] According to one embodiment, a stream of a particular hydrocarbon compound, isomer, element, mixture, or any combination thereof may be selectively removed from the circulation loop (e.g., for the purpose of generating a chemical imbalance within the process). The chemical imbalance may be engineered to increase the production of the particular hydrocarbon compound, isomer, element, mixture, or any combination thereof by the system. According to one embodiment, the system may include components that influence the TGP reaction, thereby favoring the production of the particular element, hydrocarbon compound, isomer, and / or precursor compound / radical, which restores the equilibrium.

[0019] According to one embodiment, the system may include components and systems that perform pyrolysis or decomposition of heavier hydrocarbons within the system (e.g., at a location other than the reactor drum) that promotes the production of specific hydrocarbon compounds, elements, and / or precursor compounds / radicals that restore equilibrium. The system pyrolyzes gases within the system (e.g., directly or through side reactions) into compounds and elements that restore equilibrium.

[0020] The system may be constructed to perform repeated decomposition, isomerization, reformation, or any combination thereof, of a compound, mixture, molecule, or any combination thereof contained within the loop. In operation, the system may store isomers, molecules, compounds, or any combination thereof that are thermally stable under the conditions contained within the system. The storage of thermally stable molecules may enable targeting of unstable / less stable molecules, isomers, compounds, or any combination thereof, for destruction within the system. The system may include components that maintain conditions that favor the production of targeted isomers, molecules, compounds, substances, or any combination thereof within the system.

[0021] According to one embodiment, a torrefaction, gasification, and / or pyrolysis system includes a reactor drum, a heat source for heating gas contained within the system to a temperature sufficient to torrefy particles within the reactor drum, a device for moving the heated gas thereby forming a heated gas stream that passes through the reactor drum, a duct system communicatively coupled to the heat source and the reactor drum thereby forming a recirculation loop that allows the heated gas to pass through the reactor drum multiple times, and a region for separating a first hydrocarbon compound contained within the heated gas stream from a remainder of the heated gas stream, the remainder of the heated gas stream comprising a second hydrocarbon compound that is heavier than the first hydrocarbon compound.

[0022] According to one embodiment, a method of torrefaction of particles includes producing a heated gas stream, moving the particles into an interior space of a reactor drum, directing the heated gas stream through a first end of the reactor drum and into the interior space of the reactor drum, heating the particles in the interior space of the reactor drum, thereby liberating hydrocarbon compounds from the particles in a gas phase, mixing the liberated hydrocarbon compounds with the heated gas stream, and directing the liberated hydrocarbon compounds via the heated gas stream through a second end of the reactor drum and thereby exiting the interior space of the reactor drum.

[0023] The method further includes directing the liberated hydrocarbon compounds after they exit the interior space along a route to a first end of the reactor drum, directing the liberated hydrocarbon compounds through the first end of the reactor drum and through the interior space of the reactor drum, cracking the liberated hydrocarbon compounds while they are within the interior space, thereby forming at least one lighter hydrocarbon compound, and separating the at least one lighter hydrocarbon compound from a remainder of the heated gas stream. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram of a system according to one embodiment.

[0025] [Diagram 2] FIG. 2 is a schematic diagram of an integrated processing system according to one embodiment.

[0026] [Diagram 3] FIG. 3 is an isometric view of a system according to another embodiment.

[0027] [Figure 4] FIG. 4 is a rear isometric view of the system of FIG.

[0028] [Diagram 5] FIG. 5 is a side elevational view of the system of FIG.

[0029] [Figure 6] FIG. 6 is a top plan view of the system of FIG.

[0030] [Figure 7] FIG. 7 is a side elevational view of the reactor drum and adjacent components of the system of FIG.

[0031] [Figure 8] FIG. 8 is a cross-sectional view of the reactor drum of FIG. 7 taken along line 6-6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] In the following description, certain specific details are set forth to provide a thorough understanding of various disclosed embodiments. However, those skilled in the art will recognize that the embodiments may be practiced without one or more of these specific details. In other instances, well-known structures or steps associated with industrial process equipment and industrial processes may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0033] For example, it will be understood by those skilled in the art that various sensors (e.g., temperature sensors, oxygen sensors, etc.), control devices, and other industrial process controls can be provided and managed via a programmable logic controller (PLC) or other suitable control system to monitor the systems described herein, control the operating parameters of the process, and optimize or adjust the properties of the resulting torrefied particles.

[0034] Unless the context otherwise requires, throughout the specification and the claims which follow, the words "comprise" and variations thereof, such as "comprises" and "comprising," are to be interpreted in an open-ended inclusive sense, i.e., as "including, but not limited to."

[0035] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, particular features, structures, or characteristics described herein may be combined in any suitable manner in one or more embodiments.

[0036] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the content clearly dictates otherwise. Also, it should be noted that the term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise.

[0037] Recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, including the stated endpoints of the range, unless otherwise stated herein, and each separate value is incorporated into the specification as if it were individually recited herein.

[0038] The headings provided herein and the Abstract of the Disclosure are for convenience only and do not interpret the scope or meaning of the embodiments.

[0039] FIG. 1 shows a schematic diagram of a system 10 (e.g., a torrefaction, gasification, and / or pyrolysis system) according to one exemplary embodiment. The system 10 includes a reaction chamber or vessel (referred to herein as a reactor drum 12), which is supported for rotation about a longitudinal axis 16 of the reactor drum 12. The reactor drum 12 includes an interior volume that may be cylindrical, as shown, or another tubular shape (e.g., rectangular, square, irregular, etc.) that corresponds to the shape of the outer wall of the reactor drum 12. The shape of the interior volume may be constant along some or all of the length of the reactor drum 12, or the shape may vary (e.g., tapered) along the length of the reactor drum 12. The system 10 may further include an inlet 22 for receiving particles (e.g., biomass particles) to be processed, as represented by the arrow labeled as 24. An airlock or dual airlock 26 with an optional inert or semi-inert gas purge 27 or similar device may be coupled to the inlet 22 to substantially prevent oxygen from entering the system 10 as the particles are fed into the system 10. The particles may be fed to the inlet 22 via a conveyor or other conventional material transport mechanism. In one embodiment, a plug-feeding screw conveyor is used in place of an airlock to create a plug of material, which may act as a seal when passing the particles through the inlet 22.

[0040] The system 10 may further include a heat source 30 disposed upstream of the reactor drum 12. The heat source may provide heat to the gas stream 34 generated in the system 10 (e.g., by a fan device 32). According to an embodiment, the fan device 32 may be, for example, a draft fan device or a forced draft fan device. The fan device 32 may be operable to draw or push the gas through the reactor drum 12 in a recirculation fashion and circulate the gas (or a substantial portion of the gas) back to the heat source 30 to be reheated and fed to the reactor drum 12. In some embodiments, 80 percent or more by volume of the gas exiting the reactor drum 12 may be recirculated to the inlet of the reactor drum 12. In some embodiments, 90 percent or more by volume of the gas exiting the reactor drum 12 is recirculated to the inlet of the reactor drum 12. In some embodiments, 95 percent or more by volume of the gas exiting the reactor drum 12 is recirculated to the inlet of the reactor drum 12.

[0041] During operation, the gas flow 34 may act as a thermal fluid and transfer thermal energy to the particles within the reactor drum 12. According to one embodiment, the gas flow 34 may also provide a motive force for the transport of the particles. The gas flow 34 may also heat the internal structures of the reactor drum 12 (e.g., some of the lifting flights 170, or other structures within the reactor drum 12 that directly contact the particles), which may in turn heat the particles. Two of the several lifting flights 170 are visible through the cutouts 17 provided in the illustration of the reactor drum 12, providing visibility of a portion of the internal structure of the reactor drum 12, including the lifting flights 170.

[0042] System 10 may include an appropriately sized gas duct 36 coupled to at least reactor drum 12, heat source 30, and fan device 32 for recirculating gas stream 34 within system 10. According to one embodiment, a portion, up to all, of the gas entering reactor drum 12 is recirculated in a continuous manner back to the inlet of reactor drum 12. In some embodiments, no new gas (other than unintentional leakage) is fed to the recirculating gas stream 34 during operation.

[0043] According to one embodiment, the system 10 may include multiple stages with different temperatures, residence times, chemistries, and / or operating conditions. The multiple stages may be mechanically separated from one another. The system 10 may include multiple drums with, for example, airlocks and hoppers. The system 10 may also include drums that use solids (e.g., progressive screw features, conical geometries, circulating / fluidized solids traps, and / or porting) to provide separation between sections. The system 10 may use solids involved in the TGP process or solids independent of the TGP process (e.g., ceramic media and / or sand). The system 10 may include features, cavities, ducting, and / or other components that add and / or remove elements and / or compounds to the gas stream 34 between the mechanically separated sections.

[0044] Torrefaction, gasification, and / or pyrolysis of particles in reactor drum 12 may liberate compounds (e.g., hydrocarbons in the gas phase) that enter and mix with gas stream 34. System 10 may include components that release or vent a quantity of gas from gas stream 34 to maintain a relatively stable pressure within system 10. According to an embodiment, system 10 may include components 15 that allow for extraction of specific (e.g., targeted) compounds from gas stream 34. Component 15 may include a heater, cooler, pressurizer, separator, or any combination thereof. Component 15 may be applied to the complete gas stream 34 or any percentage portion of gas stream 34.

[0045] Region 18 may include media and / or media systems to complement the separation of compounds from gas stream 34. System 10 may include media in a separate vessel (e.g., a structured media column). A structured media column may operate dry and provide a large surface area for condensation and / or evaporation. The column may operate with fluids or fluidized solids, for example, and utilize adsorption / desorption of elements and compounds in gas stream 34. System 10 may also include media directly in the system (e.g., a ceramic media bed introduced with the material at the inlet). The system may also include media that are regenerative via another process and operate in a batch mode. System 10 may also include media that are continuously regenerated or consumed, for example, as part of a cycle and / or another process. System 10 may also include media that operate via established methods, such as, for example, an electrostatic precipitator.

[0046] The system 10 may include a region 18 where components that allow for the extraction of specific compounds are removed from the gas stream 34. According to an embodiment, the region 18 may include both a temperature range and a pressure range that encourages liquid dropout of the target compounds. The target compounds may include a category of specific compounds (e.g., alkanes, alkenes, etc.) or the target compounds may include specific compounds (e.g., methane, butane, etc.). For example, the gas stream 34 may include both light and heavy hydrocarbons. As used herein, "light hydrocarbons" refers to hydrocarbons with lower molecular weights (e.g., hydrocarbons containing 1-11 carbon atoms), examples include octane, propane, propanol, cyclohexane, and pentane. As used herein, "heavy hydrocarbons" refers to hydrocarbon compounds with higher molecular weights (e.g., hydrocarbons containing 12 or more carbon atoms), examples include dodecane, pentadecane, icosane, and polymerized light hydrocarbon molecules / chains.

[0047] Region 18 may contain a temperature and pressure below the dew point of the target compounds (e.g., heavy hydrocarbons) such that the heavy hydrocarbons transition from their current gas phase to a liquid phase while the light hydrocarbons remain in the gas phase as they pass through region 18. The liquid form of the heavy hydrocarbons may then be extracted from system 10, as indicated by arrow 21, while the light hydrocarbons pass through region 18 and remain in the circulation loop.

[0048] Region 18 may include features that allow for the removal of gaseous light hydrocarbons from system 10 (e.g., once the heavy hydrocarbons have been removed, as described above). Region 18 may also include features that allow for the condensed heavy hydrocarbons removed from gas stream 34 to be returned to a gaseous state and then reintroduced into the gas stream from which the light hydrocarbons were removed, as described above.

[0049] According to one embodiment, the temperature in region 18 can be from about 0° F. to about 1,200° F. and the pressure can be between about 0.01 psia and about 2,500 psia. As gas stream 34 passes through region 18, heavier hydrocarbons (e.g., dodecane) can transition from the gas phase to a liquid phase and drop out of gas stream 34. The liquids can then be removed from system 10 and collected or returned to a gaseous state and reintroduced into system 10.

[0050] The system 10 may be calibrated to increase production of target compounds. According to one embodiment, the torrefaction, gasification, and / or pyrolysis of particles (e.g., biomass particles) in the reactor drum 12 liberates hydrocarbons from the particles. These hydrocarbons may be "boiled off" from the particles so that they are liberated in the gas phase. Upon liberation from the particles, the liberated hydrocarbons are typically of the heavier variety. The gaseous by-products that are boiled off from the particles in the previous torrefaction system / process are typically treated as waste or excess material to be disposed of. In some cases, the gaseous by-products may be sent to a burner to extract some of the benefit as a low-quality fuel to help heat the system 10 and minimize losses.

[0051] However, according to one embodiment, the gaseous by-products may be refined within system 10 into more valuable compounds (e.g., "lighter" hydrocarbons), which may then be extracted for use or sale. System 10 may cycle gas stream 34 such that gas stream 34 is exposed to a target temperature range for a target time interval, with the particular target range and interval being selected based on the time and temperature required to pyrolyze the heavier hydrocarbon compounds into lighter hydrocarbon compounds. According to one embodiment, products of system 10 may include torrefied materials, biochar, activated carbon precursor, liquid bio-oil, and gas.

[0052] System 10 may also be used to treat, reduce, and burn waste materials such as those generated in other industries (e.g., municipal solid waste, abandoned materials, plastics, agricultural by-products, etc.). These waste materials may first undergo at least one TGP reaction that liquefies the material. Devolatilization allows for treatment of potentially undesirable compounds prior to pyrolysis in system 10 and combustion of the remaining solids (e.g., dechlorination of polyvinyl chloride contaminated construction / demolition waste that, if burned or treated untreated in / by conventional TGP systems / methods, may result in the production of toxic compounds such as dioxins).

[0053] The time required for the cracking of heavy hydrocarbons into lighter hydrocarbons may be longer than the amount of time it takes for gas stream 34 to pass through the length of reactor drum 12. Thus, system 10 may be calibrated such that gas stream 34 (including gases, water vapor, and / or compounds generated from the TGP reaction) is cycled multiple times through reactor drum 12. This may result in certain portions of gas stream 34 (e.g., heavy hydrocarbons) being exposed to high temperatures (e.g., from about 400° F. to about 1,600° F.) for periods of time that exceed the amount of time the particles are exposed to high temperatures within reactor drum 12.

[0054] The temperatures used to crack heavy hydrocarbons into lighter hydrocarbons and / or for pyrolysis of compounds may be higher than the temperatures used for torrefaction of particles. Thus, system 10 may be calibrated such that gas stream 34 (including gases, steam, and / or compounds generated from the TGP reaction) is circulated through heat exchanger 60 to raise the temperature above that used in drum 12 (e.g., above about 400° F. to about 2,400° F.).

[0055] According to one embodiment, a particular portion of gas stream 34 may be exposed to the elevated temperature for about 100% to about 1,000% of the time it takes the solid particles to traverse the length of the reactor drum. For example, a particular portion of gas stream 34 may be circulated through reactor drum 12 at least 2 times to 100 times.

[0056] The system 10 may include components that enable catalytic cracking of heavy hydrocarbons in the gas stream 34 into lighter hydrocarbons. According to one embodiment, the system 10 may include a catalyst (e.g., a fluidized or low density bed of material) through which the gas stream 34 passes to facilitate the cracking of heavy hydrocarbons in the gas stream 34 into lighter hydrocarbons.

[0057] The system 10 may include a solid phase catalyst and / or catalytic element to facilitate adsorption, decomposition, reformation, and / or separation of elements and / or compounds from the gas stream 34. The system 10 may also include a catalyst and / or catalytic element to modify the characteristics of the TGP reaction and / or modify the products / outcomes generated during TGP reaction / system operation. The system 10 may include a catalyst and / or catalytic element that is regenerated or consumed during operation. The system 10 may include a catalyst and / or catalytic element that is entrained in the gas stream 34 and circulated by the fan device 32. The system 10 may include a catalyst and / or catalytic element that is regenerated or consumed during operation. The system 10 may include a catalyst and / or catalytic element that forms a bed in a drum and absorbs, for example, chlorine and / or sulfur compounds.

[0058] The system 10 may include a fluidized bed within the reactor drum 12 or as an external component. The system 10 may include features for passing the circulating gas stream 34 through the fluidized bed, either independently or utilizing a gas loop as the primary means of fluidization. The system 10 may include catalysts and / or catalytic elements within the fluidized bed and / or bed material. The system 10 may include features for mechanically fluidizing the bed (e.g., holes, screens, and / or flights incorporated within the reactor drum 12). The system 10 may also include additional elements and / or compounds in the fluidized bed to promote / initiate additional reactions. The system 10 may include features, systems, and / or mechanisms for introducing an oxidant comprising about 1% to about 100% oxygen for purposes of combustion and / or oxidation reactions within the bed.

[0059] As shown in the illustrated embodiment, the heat source 30 may be in the form of a gas / gas heat exchanger 60. A hot gas stream 35 (e.g., in the range of about 800°F to about 2,400°F) may be supplied to the heat exchanger 60 via an inlet conduit 62. The hot gas stream 35 may interact with the recirculating gas stream 34 of the system 10 and transfer heat to the gas stream 34, as shown. In some embodiments, the heat exchanger 60 may increase the inlet temperature of all or a portion of the recirculating gas stream 34 into the heat exchanger 60 (e.g., from about 500°F±100°F to an outlet temperature of about 1,600°F±150°F).

[0060] By doing so, the temperature of the hot gas stream 35 in the heat exchanger 60 is necessarily reduced before it exits the heat exchanger 60 via the outlet conduit 66. However, the temperature of the hot gas stream 35 may still be high enough to be useful in other processes, such as drying particles, prior to entering the system 10. Thus, in some embodiments, the hot gas stream 35 exiting the heat exchanger 60 via the outlet conduit 66 may be sent to a dryer system 70 (as shown in FIG. 2) or other device. In some embodiments, the exiting hot gas stream 35 may be sent back to the inlet of the heat exchanger 60 and mixed with other heated gases having a higher temperature (such as other heated gases sent from the burner 76) to adjust the inlet temperature of the hot gas stream 35 as it enters the heat exchanger 60 to a desired level (or to be within a desired temperature range).

[0061] 1 is shown as a gas-to-gas heat exchanger 60, it should be understood that a variety of other heat sources 30 may be provided. For example, in some embodiments, an electric immersion type heat source may be provided in the path of the gas stream 34 of the system 10. In other embodiments, a low-oxygen burner may be introduced directly into the system 10 to heat the gas stream 34 without significantly increasing the oxygen level within the system 10. However, regardless of the heat source 30, it may be beneficial to separate the gas stream 34 in a recirculation manner to facilitate maintaining a low-oxygen environment within the reactor drum 12 conducive to torrefying the particles.

[0062] System 10 may include a separator hopper 38 that collects torrefied particles (e.g., torrefied wood chips, torrefied giant cane chips, other torrefied cellulosic biomass) as the particles exit reactor drum 12 (e.g., at the downstream end of reactor drum 12). These particles may then be mechanically and / or gravity fed toward outlet 40 for collection. One or more airlock devices 42 may be coupled to outlet 40 to substantially prevent oxygen from entering system 10 as the torrefied particles are withdrawn from system 10.

[0063] Smaller particles that may pass through the separator hopper 38 (e.g., torrefied wood particulates, torrefied giant cane particulates, other torrefied cellulosic biomass) may be filtered and removed from the gas stream 34 by a filtration device 44 (e.g., a cyclone-type filtration device). One or more additional airlock devices 46 may be coupled to a secondary outlet 48 to remove filtered material from the system 10 without introducing significant amounts of oxygen into the system 10. As shown, the smaller particles exiting the separator hopper 38 via the one or more airlock devices 46 may be directed to be mixed / combined with the torrefied particles exiting the separator hopper 38.

[0064] In some embodiments, the chamber or space between a pair of serially aligned airlocks 42, 46 may be coupled to a steam source, an inert or semi-inert gas source, that selectively purges the chamber or space, as represented by the arrows labeled as 43 and 47. In some embodiments, system 10 may include a cyclone-type filtering device in place of hopper 38 to separate and / or filter the torrefied particles from gas stream 34. In some embodiments, system 10 may include one or more pneumatic exhaust devices (not shown) to exhaust the torrefied particles from system 10.

[0065] As already explained, the gas stream 34 may be drawn or forced through the reactor drum 12 under the influence of the fan device 32 and returned to the heat source 30 (e.g., after separating torrefied particles, chips, fines, dust, and / or any debris). A substantial majority of the gas is recirculated, but some gas may be redirected to exhaust ducts 50. The gas exhausted through exhaust ducts 50 may be used either in the process or in another process, as represented by the arrow labeled as 52. For example, the exhaust gas may be used as fuel to generate heat and assist the heat source 30 in increasing the temperature of the gas stream 34 (e.g., via the fuel inlet 23 of the burner 76). The burner 76 may be run on a "complementary fuel" source (e.g., fuel that is added to the system 10 rather than produced by the system 10) via the fuel inlet 23 and the oxygen inlet 25. The gas ducts 36 (e.g., exhaust ducts 50) may include a variable position damper 54, which may be used to balance the pressure inside the reactor drum 12 from slightly negative to slightly positive. Depending on the setup, this may be used to prevent oxygen from entering the system 10.

[0066] Referring to FIG. 2, an embodiment of an integrated processing system 11 (e.g., a torrefaction, gasification, and / or pyrolysis system) is shown in schematic form. System 11 may include, among other things, system 10 described above and a dryer system 70 that dries particles prior to introduction into system 10. In some embodiments, system 10 may receive particles having a moisture content reduced by dryer system 70 to a moisture content of less than 20 percent on a wet weight basis. In some embodiments, the biomass particles may be wood chips having an average particle size of about 1 / 16 cubic inch to about 1 cubic inch and having an initial moisture content of greater than 40 percent moisture content on a wet weight basis. In some embodiments, the particles may have a substantially consistent size (less than 10 percent difference), while in other embodiments, the particles may vary in size by up to 10 percent, up to 20 percent, up to 30 percent, or more.

[0067] As shown, dryer system 70 may include a rotatable drum 71 supported for rotation about a longitudinal axis 72 of the rotatable drum 71. Dryer system 70 may further include an inlet 74 for receiving particles to be processed, as represented by the arrow labeled as 75. The particles may be fed to inlet 74 via a conveyor or other conventional material transport mechanism.

[0068] The dryer system 70 may be coupled to a burner (e.g., burner 76) that feeds a heated gas stream, represented by arrow 84, through the rotary drum 71 for heating and drying, and the dryer system 70 may additionally convey (e.g., intermittently) particles through the drum 71 as it rotates. According to one embodiment, the heated gas stream 84 may simultaneously dry the particles as the heated gas stream propels the particles through the rotary drum 71. The burner 76 may be configured to burn bark, ground fuel, or other fuel (e.g., waste wood) to heat the heated gas stream 84 that is fed to the dryer system 70. The heated gas stream 84 entering the dryer system 70 may be supplemented or mixed with other gas streams of the integrated processing system 11, as described in further detail elsewhere herein.

[0069] At the downstream end of the rotary drum 71, the integrated processing system 11 may include a separator hopper 78 that collects the dried particles (e.g., dried wood chips, dried giant cane chips, other dried cellulosic biomass) as the particles exit the rotary drum 71. These particles may then be mechanically and / or gravity fed toward an outlet 79 for collection for further use or packaging. Smaller particles and dust (e.g., dried wood fines, dried giant cane fines, other dried cellulosic biomass) that may pass through the separator hopper 78 may be filtered and removed from the heated gas stream 84 by a filtering device 80, such as, for example, a cyclone-type filtering device. These particles may be fed toward a secondary outlet 81 for further use or packaging. In some embodiments, the dryer system 70 may include a cyclone-type filtering device instead of the hopper 78 to separate and / or filter the dried particles from the heated gas stream. In some embodiments, dryer system 70 may include one or more pneumatic exhaust devices (not shown) to exhaust the dried particles from dryer system 70 .

[0070] A fan device 92 may be provided to draw or push the heated gas stream through the rotary drum 71, as represented by the arrow labeled as 83, and direct the exhaust gas from the rotary drum 71 toward an environmental emission control device 82 for treating the exhaust of the dryer system 70 before releasing it to the environment or other systems. By way of example, the emission control device 82 may include a wet electrostatic precipitator (WESP) to facilitate removal of sub-micron sized solid particles and liquid droplets from the exhaust gas stream. The emission control device 82 may further include a regenerative thermal oxidizer (RTO) to destroy air toxins and volatile organic compounds (VOCs) that may be present in the exhaust gas. In some embodiments, an RTO may be provided that uses natural gas to heat the exhaust gas to about 1,500° F., and the VOCs are oxidized. In other embodiments, the torrefied off-gas may be used to heat the RTO, which may significantly reduce the operating costs of the RTO (as natural gas is otherwise a significant cost in operating such equipment).

[0071] At least a portion of the exhaust gas from dryer system 70 may be routed or recirculated (e.g., via ducting) back toward inlet 74 of rotary drum 71 and combined with heated gas from burner 76 for drying particles continuously fed into rotary drum 71. Additional gas from an outlet of heat exchanger 60 of system 10 may also be combined with the exhaust gas from dryer system 70 for cleaning before discharge into the environment and / or for introduction back into dryer system 70, as represented by the arrow labeled as 85.

[0072] According to the illustrated embodiment of Figure 2, the dried particles (e.g., dried wood chips and fines) may be sent to another location for further processing of the dried particles, storage, or packaging as a stand-alone item, as represented by the arrow labeled as 86. A portion or the entire supply of dried particles may be sent to system 10 for further processing, as indicated by the arrow labeled as 87.

[0073] As shown in Figure 2, dried particles generated via dryer system 70 may serve as an input material for system 10. In some embodiments, the dried particles may have an average moisture content of less than 20 percent moisture on a wet weight basis as they enter system 10. In other embodiments, the average moisture content of the dried particles may be between about 5 percent moisture on a wet weight basis and about 15 percent moisture on a wet weight basis. In yet other embodiments, the average moisture content of the dried particles may be greater than 20 percent moisture on a wet weight basis.

[0074] Although dryer system 70 is illustrated as a rotary drum type dryer system, such as that designed and marketed by the assignee of the present application, Teal Salesin incorporated, it should be understood that other dryer systems may be utilized in connection with embodiments of the present invention, including, for example, kilns having a rotary screw and conveyor bed type transport mechanism. Thus, embodiments of the particle processing system described herein are not limited to the particular dryer system illustrated, but may incorporate a wide range of conventional dryer systems.

[0075] As shown, system 11 may include a heat source 30 (e.g., gas / gas heat exchanger 60) that receives a heated gas stream (e.g., heated gas stream 35 from burner 76), as indicated by the arrow labeled as 88. The heated gas stream entering heat exchanger 60 may be mixed with gas from an output of heat exchanger 60 (e.g., via burner 76) to adjust the input temperature of the heated gas stream entering heat exchanger 60. In some embodiments, the inlet temperature of the gas stream entering heat exchanger 60 may be between about 600°F and about 1,400°F, and in some embodiments, the inlet temperature of the gas stream entering heat exchanger 60 may be between about 800°F and about 1,000°F.

[0076] The recirculating gas stream 34 of the system 10 passing through the heat exchanger 60 may be heated to a reactor drum inlet temperature of at least 500° F. according to some embodiments. After passing through the reactor drum 12, the heated gas stream may have a reactor drum outlet temperature of at least 400° F. As a result, during operation, particles passing through the reactor drum 12 may be exposed to a heated gas stream having a temperature of at least 400° F. directly throughout the entire length of the reactor drum 12. In some embodiments (e.g., when processing cellulosic biomass), the reactor drum inlet temperature is about 700° F.±150° F. and the reactor drum outlet temperature is about 500° F.±100° F. The reactor drum inlet and outlet temperatures may be varied to accommodate processing temperatures for other particles (e.g., those containing plastics). The reactor drum inlet and reactor drum outlet temperatures of the heated gas stream may be monitored using appropriate temperature sensors and controlled via general or cascaded control loops to maintain the temperature gradient through the reactor drum at a desired level during operation.

[0077] Exhaust gas from the torrefaction, gasification, and / or pyrolysis process may be sent to burner 76 for combustion, as indicated by the arrow labeled as 91, according to some embodiments. The exhaust gas from the torrefaction, gasification, and / or pyrolysis process may include hydrocarbon compounds that are "boiled off" from the particles (i.e., generated during the torrefaction), in addition to other components such as water vapor and any ambient air that leaks into the system. System 11 may include separator 13, which separates all or a portion of the hydrocarbon compounds from the remainder of the exhaust gas. System 11 may thus direct the hydrocarbon compounds back toward reactor drum 12, thereby retaining the hydrocarbon compounds and increasing their exposure time to enable thermal / catalytic decomposition of the hydrocarbon compounds into lighter hydrocarbon compounds. Separator 13 may direct at least a portion of the remainder of the exhaust gas (e.g., tar or other leftover hydrocarbons) to burner 76 for combustion.

[0078] In this manner, the energy contained within the exhaust gas can be utilized to heat a heat transfer medium for use in heat exchanger 60 and maintain the heated gas stream 34 flowing through reactor drum 12 at a desired elevated inlet temperature. The reactor drum temperature gradient can be controlled through a cascaded control loop, which sets the reactor drum inlet temperature. The reactor drum inlet temperature can be controlled, for example, by varying the amount of heated gas delivered from burner 76 to heat exchanger 60.

[0079] According to one embodiment, the burner 76 may operate primarily on the torrefied particles exiting the reactor drum 12 as a primary source of fuel (supplemented during start-up / shutdown and other unstable state conditions). In some embodiments, the burner 76 may receive supplemental fuel, as represented by arrow 77. The burner 76 may include an air inlet, as represented by arrow 89, to aid in the combustion process. According to one embodiment, the burner 76 may burn bark, pulverized fuel, or other fuel to heat the gas stream 35 that is fed through the heat exchanger 60. The heating of this gas stream 35 may be supplemented with the combustion of exhaust gas from the system 10, as represented by the arrow labeled as 91.

[0080] In some embodiments, steam from a separate boiler of the steam plant 93, which may be ignited by the off-gas of the reactor drum 12 (as represented by the arrow labeled as 94) or another fuel or heat source, may be injected into the system 10 to further control oxygen in the process or as a safety containment and cooling stream (as represented by the arrow labeled as 95), and the steam may also be used as an inert or semi-inert purge gas in the process. In addition, using steam passing through the reactor drum 12 as part of the process gas may also improve heat transfer to the particles. In some embodiments, the boiler may be heated by off-gas delivered to the boiler by ducting 96 coupled to the reactor drum 12. In other embodiments, the steam plant 93 may be heated by the burner 76 or another heat source. In some embodiments, in response to a fault condition, steam may be introduced into the reactor drum 12 in sufficient quantities to contain and / or cool the particles. In this manner, the operational safety of the system 10 may be improved.

[0081] As shown, system 11 (e.g., system 10) may include one or more of regions 18. The one or more regions may include a first region 18a and a second region 18b, as shown. Each of the one or more regions 18 may be calibrated to enable extraction of a particular compound from gas stream 34. According to one embodiment, first region 18a may include at least one first component 15a and second region 18b may include at least one second component 15b.

[0082] According to one embodiment, the first region 18a may include both a first temperature range and a first pressure range that results in a first liquid dropout out of the gas stream 34. The second region 18b may include both a second temperature range and a second pressure range that results in a second liquid dropout out of the gas stream 34. According to one embodiment, the first temperature may be different from the second temperature, and the first temperature and the second temperature may be different from the temperature of the tail gas upon exiting the reactor drum 12. According to one embodiment, the first pressure may be different from the second pressure, and the first temperature and the second pressure may be different from the pressure of the tail gas upon exiting the reactor drum 12. According to one embodiment, the pressure of the gas stream 34 remains substantially constant, while one or more regions 18 modify the temperature of the gas stream 34.

[0083] According to one embodiment, the first region 18a separates the first target compound from the remainder of the gas flow 34 without transitioning the first target compound from the gas phase to the liquid phase. According to one embodiment, the second region 18b separates the second target compound from the remainder of the gas flow 34 without transitioning the second target compound from the gas phase to the liquid phase. The first target compound, whether in the liquid phase, gas phase, solid phase, or a combination thereof, may be removed from the system 11 via the first outlet 21a. The second target compound, whether in the liquid phase, gas phase, solid phase, or a combination thereof, may be removed from the system 11 via the second outlet 21b.

[0084] 3-8, a torrefaction, gasification, and / or pyrolysis system 110 according to an embodiment may be similar to the system 10 previously described, whereby the present disclosure directed to the system 10 is also applicable to the system 110, with the differences described below. According to an embodiment, the system 110 may include additional structural components, a different heat source 130, or both. The system 110 may include a reactor drum 112 (e.g., reactor drum 12) supported on a structural frame 114 and rotating about a vertical axis 116. The reactor drum 112 may be driven by a drive motor 118, which may be electrically coupled to a control system that selectively controls and, optionally, adjusts the speed of rotation of the reactor drum 112. The control system may include a control panel 120 with appropriate controls (switches, dials, gauges, touch screen, etc.) for selectively controlling and monitoring the system 110. Other gauges and controls (eg, sensors, valves, etc.) may also be located remotely and coupled to certain components of the system 110 for monitoring and control purposes.

[0085] System 110 may further include an inlet 122 (e.g., inlet 22) in the form of a chute that receives particles (e.g., biomass particles) to be processed, as represented by the arrow labeled as 124. An airlock or double airlock 126 (e.g., airlock 26) with an optional steam, inert, or semi-inert gas purge or similar device may be coupled to inlet 122 to substantially prevent oxygen from entering system 110 as particles are input. Particles may be fed to inlet 122 via a conveyor or other conventional material transport mechanism. The introduction rate of particles may be monitored and controlled to optimize or tailor the properties of the resulting torrefied particles. A staircase 128 or other access device may be provided for users to access inlet 122 and other components of system 110 for monitoring, maintenance, and other purposes.

[0086] The system 110 may also include a heat source 130 (e.g., positioned upstream of the reactor drum 112, as shown) that supplies heat generated within the system 110 to the gas flow (e.g., by a fan device 132, such as fan device 32), which may be, for example, a draft fan device or a forced draft fan device. The fan device 132 may be driven by a drive motor 134 to draw or push the gas through the reactor drum 112 in a recirculating fashion, circulating the gas back to the heat source 130 to be reheated and supplied to the reactor drum 112. The system 110 may be appropriately sized for this purpose and may include a gas duct 136 coupled to at least the reactor drum 112, the heat source 130, and the fan device 132.

[0087] At the downstream end of the reactor drum 112, a separator hopper 138 (e.g., separator hopper 38) may be provided that separates the torrefied particles from the gas stream as the particles exit the reactor drum 112. The particles may then be mechanically and / or gravity fed toward an outlet 140 for collection for future use or packaging. An airlock device 142 (e.g., airlock device 42) may be coupled to the outlet 140 and substantially prevent oxygen from entering the system 110 as the torrefied particles are withdrawn.

[0088] Smaller particles and dust that may pass through the separator hopper 138 may be filtered and removed from the gas stream by a filtering device 144 (e.g., filtering device 44), such as, for example, a cyclone-type filtering device. Another airlock device 146 (e.g., airlock device 46) may be coupled to the secondary outlet 148 to remove the filtered material from the system 110 without introducing significant amounts of oxygen into the system 110. In some embodiments, the system 110 may include a cyclone-type filtering device in place of the hopper 138 to separate and / or filter the torrefied particles from the gas stream passing through the reactor drum 112. In some embodiments, the system 110 may include one or more pneumatic discharge devices (not shown) to discharge the torrefied particles from the system 110.

[0089] As already explained, the gas flow can be drawn or pushed through the reactor drum 112 under the influence of the fan device 132 and returned to the heat source 130 (e.g., after separating the torrefied particles, dust, and any debris). A substantial majority of the gas can be recycled to the reactor drum 112, but some gas can be redirected to the exhaust stack 150. The gas exhausted through the stack 150 can be recaptured for use either in the process or another process, for example, as a fuel to generate heat. The stack 150 can include a variable position damper 152, which can be used to balance the pressure inside the reactor drum 112 from slightly negative to slightly positive. Depending on the setting, it can be used to block oxygen from entering the system 110.

[0090] Further details of the reactor drum 112 will now be described with reference to Figures 7 and 8. As shown in the illustrated embodiment, the reactor drum 112 may be supported in a horizontal orientation on a number of rollers 160. The rollers 160 may contact the drum 112 along bearing tracks 162 fixed to the circumference of the drum 112. The diameter of the drum 112 may be 3 feet, 4 feet, 5 feet, or more (e.g., up to 20 feet or more) and may be configured to receive and process more than 50 tons of torrefied biomass particles per hour.

[0091] A drive motor 118 is coupled to a drive belt or chain 164 and may be controlled via a control system to selectively rotate the drum 112 at various speeds, such as, for example, above or below about 3 rpm. Precision seals 166 are disposed between the rotating drum 112 and the static components to prevent oxygen from entering the system. Thus, the seals 166 and other features of the system are capable of maintaining a consistent low level of oxygen in the gas flow by creating a substantially sealed container.

[0092] There may be several lifting flights 170 circumferentially spaced within the reactor drum 112 at each of a number of locations along its longitudinal length. The density of the lifting flights 170 may be designed to suit the various needs of the system 110 and may depend on several interrelated factors, such as, for example, the speed of rotation of the reactor drum 112, the rate of material being fed into the system 110, and the speed of the fan device 132 or the strength of the heated gas flow through the reactor drum 112.

[0093] The flights 170 may be configured to lift particles (represented by circles labeled as 177) as the reactor drum 112 rotates in the direction indicated by the arrow 172, and then direct and blast the particles 177 into the gas stream so that they are intermittently carried along the length of the reactor drum 112 and simultaneously torrefied primarily by the kinetic energy of the gas stream. As shown, the flights 170 may be fixed to the reactor drum 112 such that they rotate with the reactor drum 112 about the longitudinal axis 116. The flights 170 include a scoop-like shape to scoop up and suspend the particles (e.g., so that the particles are spaced away from the periphery of the reactor drum 112 during at least a portion of the rotation). For illustrative purposes, five "particles" 177 are shown to be carried by each flight 170. As the flights 170 rotate with the particles in contact with the flights, the movement of the particles is minimal (or zero). When the flights reach a certain point in their respective rotations (e.g., about 3 o'clock as shown in FIG. 8), the particles fall out of the flights 170 and are "bathed" into the heated gas stream flowing through the reactor drum 112. As they fall, the heated gas stream carries the particles along a portion of the length of the reactor drum 112.

[0094] This is advantageous in that the transport mechanism for the particles provides a highly efficient medium for transferring heat directly to the particles. Thus, large amounts of particles can be processed by the system with reduced energy demands. In addition, the throughput or rate (tons / hour) of torrefied biomass particles can be relatively large compared to conventional torrefaction systems of generally comparable size.

[0095] The system 110 (e.g., the flights 170 of the reactor drum 112) can generally be calibrated so that the reactor drum 112 provides sufficient forward progression of the particles (via repeated drops into the heated gas stream) to require several revolutions to gain passage through the length of the reactor drum 112. The showering and conveying process within the drum 112 can sort the particles. Lighter and smaller particles can pass through the drum 112 at a higher velocity than heavier and larger particles because the larger and heavier particles fall more quickly and / or are advanced a shorter distance along the length of the reactor drum 112 with each successive "shower" compared to the smaller and lighter particles. This allows the larger particles to remain within the drum 112 for a relatively longer residence time, producing a more uniform final product (i.e., large and small particles can be processed together to have similar final properties despite differences in mass and volume).

[0096] For example, in some embodiments, particle size may vary within a particular process of torrefied particles by 10 percent to 20 percent, 10 percent to 30 percent, or more than 30 percent (e.g., up to 100% or more), while the energy density and moisture characteristics of the particles remain relatively consistent regardless of particle size. In some embodiments, flights 170 may be designed to vary with respect to location and / or flight density in different embodiments to affect the residence time of the particles within the reactor drum 112.

[0097] Particles that reside within the drum 112 for a period of time are then subsequently discharged into a separator hopper 138 or other separation device and sent in the direction indicated by the arrow labeled as 174 for further handling. A major or substantial portion of the gas stream is sent in the direction indicated by the arrow labeled as 176 and may be recirculated, heated, and reintroduced into the reactor drum 112 as indicated by the arrow labeled as 178. The recirculation and reheating may be calibrated to promote the cracking of larger hydrocarbons that are boiled off from the particles by torrefaction, gasification, and / or pyrolysis processes into smaller / lighter hydrocarbons, as described in detail above.

[0098] System 110 may thus enable a continuous torrefaction, gasification, and / or pyrolysis process involving the introduction of particles into a rotating reactor drum 112 via an airlock or airlock 126 to maintain low oxygen levels inside the system 110 conducive to torrefying the particles. The particles may be conveyed through the reactor drum 112 by kinetic energy of a heated gas stream generated by generating draft or forced draft via a fan device 132 connected to the outlet of the drum 112 by a duct 136, or alternatively by conventional means of conveyance (e.g., a mechanical screw).

[0099] The system 110 may include a heat source 130, such as, for example, an electric immersion duct heater (as shown in FIG. 3) or a gas / gas heat exchanger (as shown in FIG. 1), upstream of the reactor drum 112. A fan device 132 may draw or push gas through the reactor drum 112 across or through the heat source 130. Recirculation of gas exiting the drum 112 back to the heat source 130 for reheating is beneficial to process viability. As discussed in more detail elsewhere, the ability of a heated gas stream to directly heat particles in a low-oxygen environment when the gas stream simultaneously transports particles intermittently through the reactor drum 112 is also beneficial to process viability.

[0100] System 110 may include components that remove / exhaust an amount of gas from system 110 (e.g., an amount substantially equal to the sum of gas dislodged from the particles due to heating and any leakage that may enter system 110). As shown in Figure 5, the components that remove / exhaust an amount of gas may include region 18, component 15, and outlet 21, as described above. The components that remove / exhaust an amount of gas may further include an outlet to the outside environment or another related or unrelated process component.

[0101] When using the system 110 to torrefy biomass particles, the heat source 130 may add heat to recirculate gas within the system 110. The heated gas stream recirculating within the system 110 may then heat the particles as they are conveyed through the system 110. In this manner, the heated gas stream may directly heat the particles and simultaneously transport the particles. This is advantageous in that the transport mechanism for the particles provides a highly efficient medium for transferring heat directly to the particles. Thus, large amounts of biomass particles can be processed by the system with reduced energy demands. In addition, the throughput or rate (tons / hour) of torrefied biomass particles can be relatively large compared to conventional torrefaction systems of generally comparable size. This advantageously allows the systems described herein to be implemented in a manner that is particularly commercially viable.

[0102] The elements of the heat source 130 can provide heat by any readily available energy source. In some embodiments, for example, direct heat can be added to the gas stream by an electric element (e.g., electric immersion duct heater 130). In other embodiments, heat can be provided to the gas stream (as shown in FIGS. 1 and 2) through a gas / gas heat exchanger 60 that is coupled to a combustion and / or waste heat system (e.g., burner 76 in FIGS. 1 and 2). In another embodiment, a low-oxygen burner can be introduced directly into the system 110 to heat the gas stream without significantly increasing the oxygen level within the system 110. According to one embodiment, heat can be provided to the gas stream by localized introduction of an oxidizer that includes between about 1% oxygen and about 100% oxygen.

[0103] In some embodiments, the tail gas exiting stack 150 may be used as part of the process to heat fuel. According to one embodiment, the torrefied particles exiting reactor drum 112 may be directed to be consumed as fuel for heat source 130. Regardless of heat source 130, very little additional oxygen may be added to system 110 throughout the heating portion of the process.

[0104] Torrefaction, gasification, and / or pyrolysis systems and processes may be based on a heat and energy balance that balances the energy required with the process rate, the heat source, and the required residence time. The torrefaction, gasification, and / or pyrolysis system and method embodiments described herein are particularly well suited to manipulate and control these factors and provide systems and methods that are easily scalable to meet various industrial needs.

[0105] For example, the residence time of the particles in the reactor drum 112, the gas flow (e.g., hydrocarbons that are boiled off from the particles in the reactor drum 112), or both, can be controlled by various design and process factors. For example, the speed and size of the fan device 132 can be selected to adjust the velocity of the circulating heated gas in the drum 112. In addition, the speed and volume of the heated gas flow can also be adjusted by a fan inlet damper of the fan device 132. As another example, the rotational speed of the drum 112 can be set higher or lower to adjust the rate of lift and splash effects in the drum 112, thus creating more or less time that the particles are suspended.

[0106] Additionally, the flights 170 can be designed to operate over a wide range of rotational speeds, so that the drum 112 rotational speed can be selectively adjusted by appropriate controls (such as a variable speed drive motor) to adjust residence time. The density of the flights 170 within the reactor drum 112 can also be used to vary the flow conditions inside the reactor drum 112, imparting shorter or longer residence times specific to individual designs. Still further, the size and shape of the flights 170 can be modified to meet the needs of the material being processed, producing a more or less pronounced splash effect, thereby affecting residence time within the drum 112.

[0107] In some embodiments, the flights 170 may be fixed in the drum 112 at a particular density and configuration to optimize or tune the properties of the resulting torrefied particles, the circulating gas flow, or both. The length of the reactor drum 112 may also be varied in the initial design to create more or less residence time for the particles, the circulating gas flow, or both. Additionally, the particle loading conditions may be varied to create more or less resistance to the gas flow within the reactor drum 112, thus affecting the residence time.

[0108] For example, in some embodiments, a relatively larger volumetric flow rate of the particles can be set to slow down the progression of the particles through the reactor drum 112 so that they crowd inside the drum 112. Conversely, a relatively smaller volumetric flow rate of the biomass particles can be set to reduce crowding inside the reactor drum 112 and accelerate the progression of the biomass particles through the reactor drum 112.

[0109] The oxygen level inside the drum 112 can be similarly controlled by a variety of design and process factors. For example, the mechanical design of the particle inlet can be selected to include, for example, an airlock, a gas purged double airlock, a screw mechanism, etc., each mechanism having a different level of ability to prevent oxygen ingress. Preferably, the amount of oxygen entering the system 110 with the particles is minimized, but will likely vary with design according to the particle size of the biomass being treated and / or the desired production rate. Additionally, the inlet moisture content of the particles can be varied to control the oxygen level.

[0110] During processing, the resulting evaporated moisture partially replaces oxygen in the system 110, and thus the moisture level can be varied as appropriate for production requirements (e.g., less initial moisture means less energy is required to torrefy the particles, and more initial moisture brings less oxygen into the system). Still further, it should be recognized that as volatiles and moisture are evaporated from the particles, there is some net addition of gas to the system. As already explained, this excess gas can be vented from the system 110 via the stack 150 and, according to some embodiments, can be recaptured for use either in the process or another process, such as for example, for use as a fuel to generate heat. The stack 150 can include a variable position damper 152, which can be used to balance the pressure inside the reactor drum 112 from slightly negative to slightly positive. Depending on the setting of the damper 152, it can be used to block oxygen from entering the system 110.

[0111] In some embodiments, moisture levels can be precisely controlled within system 110 to modify compounds contained within the gas stream via established principles of the water-gas shift / reverse water-gas shift reaction (e.g., water combines with carbon monoxide to produce hydrogen and carbon dioxide).

[0112] In some embodiments, many of the various operating parameters discussed above and others may be adjusted (manually or automatically) during operation. In other embodiments, the operating parameters may be established prior to operation. Regardless of the particular control scheme, the ability to independently control the various operating parameters of the systems described herein provides versatile systems and methods that are adaptable to changing conditions, such as, for example, the moisture content of the particles selected to be processed and the desired energy density of the resulting torrefied particles (which may vary).

[0113] The system 110 is provided with precision seals 166 at the connections between rotating and stationary parts, and at other low leakage connections and components, to provide a particularly well-sealed container and to maintain a consistently low level of oxygen within the system 110.

[0114] Various safety devices may also be incorporated into the torrefaction, gasification, and / or pyrolysis system to improve operational safety. For example, the system may be equipped with a vent that will burst or open if a small explosion or deflagration large enough to potentially cause equipment damage occurs. As another example, spark detection and extinguishing systems, such as those commercially available from Tigard, Oregon-based GreCoN, Inc. and components, may also be integrated into the torrefaction, gasification, and / or pyrolysis system. In addition, system operating characteristics may be monitored, for example, by various sensors (e.g., temperature, pressure, oxygen, etc.), and the obtained operating data may be used to adjust and control the system, improve safety, or optimize the torrefaction, gasification, and / or pyrolysis process, as needed. In some embodiments, real-time mass spectroscopy may also be used to identify compounds in the gas stream and adjust or control the system, improve safety, or optimize the torrefaction, gasification, and / or pyrolysis process, as needed.

[0115] Overall, by knowing which process heat, water, residence time, and oxygen levels are to be controlled, and by having flexibility through the initial design and numerous process variables described herein, embodiments of the system and method can be configured to accommodate a variety of feedstocks under a variety of local conditions and provide the flexibility and control needed to achieve consistent torrefaction, gasification, and / or pyrolysis results. In some embodiments, for example, the system and method can be configured to torrefy biomass particles in the form of wood chips at a minimum rate of 1 ton of torrefied biomass particles / hour, with the resulting torrefied biomass particles having an energy density of at least 20 GJ / ton. In some embodiments, the system and method can also refine heavy hydrocarbons while torrefying, gasifying, and / or pyrolyzing the particles, which are boiled off from the particles into light hydrocarbons that can then be extracted from the system.

[0116] The systems and methods described herein are particularly well suited for providing continuous processes that have many advantages over conventional systems, particularly batch systems and methods that require batch processing of biomass particles in furnaces, kilns, or other similar devices. The continuous nature of the systems and methods described herein allows, among other things, relatively higher production rates. In addition, the efficiency with which biomass particles can be processed using the systems and methods allows for high material throughput at relatively lower energy demands.

[0117] Although the embodiments of the systems and methods described herein are illustrated in the figures as including a reactor drum rotating about a horizontally aligned axis of rotation, it should be understood that in some embodiments, the axis of rotation may be tilted. In such embodiments, gravity may play a key role in transporting the biomass particles through the reactor drum. In addition, although the embodiments of the systems and methods are described herein as involving a heated gas flow passing through the reactor drum to simultaneously transfer heat to the biomass particles and torrefy them while carrying (or transporting) the biomass particles, it should be understood that in some embodiments, the biomass particles may be transported by alternative mechanisms (e.g., gravity, a screw device, a conveyor device, etc.) and exposed to a countercurrent heated gas flow within the reactor drum to torrefy the biomass particles.

[0118] Moreover, the various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above detailed description. Generally, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and claims, but rather to include all possible embodiments, along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. A system comprising: A reactor drum; a heat source for heating a gas contained within the system to a temperature sufficient to torrefy particles within the reactor drum; a device for moving the heated gas thereby forming a heated gas stream passing through the reactor drum; a duct system communicatively coupled to the heat source and to the reactor drum, thereby forming a recirculation loop that allows the heated gas to pass through the reactor drum multiple times; a region that facilitates separation of a first hydrocarbon compound contained within the heated gas stream from a remainder of the heated gas stream; Equipped with The remainder of the heated gas stream comprises a second hydrocarbon compound that is heavier than the first hydrocarbon compound.

2. 10. The system of claim 1, further comprising an inlet communicatively coupled to the reactor drum, whereby particles received by the inlet subsequently enter the reactor drum.

3. The system of claim 2 , wherein the heat source heats the gas contained within the system to a temperature sufficient to liberate the second hydrocarbon compound from particles in the gas phase.

4. 4. The system of claim 3, wherein the heat source heats the gas to a temperature of from about 220° F. to about 1,250° F. as measured while the heated gas stream is in the reactor drum.

5. 4. The system of claim 3, wherein the released second hydrocarbon compound travels along the recycle loop and passes through the reactor drum multiple times.

6. The system of claim 1 , further comprising at least one component facilitating separation of the first hydrocarbon from the remainder of the heated gas stream.

7. The system of claim 6 , wherein the at least one component changes a temperature, a pressure, or both of the heated gas stream as the heated gas stream passes through the region.

8. 8. The system of claim 7, wherein the component reduces a temperature of the heated gas stream below a dew point of the first hydrocarbon, thereby causing the first hydrocarbon to transition from a gas phase to a liquid phase.

9. 10. The system of claim 8, further comprising an outlet for evacuating the first hydrocarbon in the liquid phase from the recirculation loop.

10. 10. The system of claim 9, wherein the outlet comprises an airlock, the airlock limiting entry of oxygen into at least the recirculation loop during the eviction of the first hydrocarbon from the recirculation loop.

11. 1. A method for producing hydrocarbons, the method comprising: Producing a heated gas stream; moving the particles into an interior space of a reactor drum; directing the heated gas stream through a first end of the reactor drum and into the interior space of the reactor drum; heating the particles within the interior space of the reactor drum, thereby liberating hydrocarbon compounds from the particles in a gas phase and mixing the liberated hydrocarbon compounds with the heated gas stream; directing the liberated hydrocarbon compounds by the heated gas stream through a second end of the reactor drum, thereby exiting the interior space of the reactor drum; directing the released hydrocarbon compounds after exiting the interior space along a route to the first end of the reactor drum; directing the released hydrocarbon compounds through a first end of the reactor drum and through the interior volume of the reactor drum; decomposing the liberated hydrocarbon compounds while they are within the interior space, thereby forming at least one lighter hydrocarbon compound; and separating said at least one lighter hydrocarbon compound from the remainder of said heated gas stream; A method comprising:

12. The method of claim 11 , wherein heating the particles comprises heating the particles to about 220° F. to about 1,250° F.

13. 12. The method of claim 11 , wherein the route is formed by ducts connecting the second end of the reactor drum to the first end of the reactor drum without passing through the interior space of the reactor drum.

14. 12. The method of claim 11, wherein cracking the liberated hydrocarbons comprises passing the liberated hydrocarbons through the reactor drum multiple times.

15. 12. The method of claim 11, wherein cracking the liberated hydrocarbons comprises exposing the liberated hydrocarbons to the interior space of the reactor drum for a residence time.

16. 16. The method of claim 15, wherein the residence time occurs over multiple passes through the interior space of the reactor drum.

17. 12. The method of claim 11, wherein moving the particles throughout a length of the interior space of the reactor drum comprises a particle residence time.

18. 17. The method of claim 16, wherein cracking the liberated hydrocarbons comprises exposing the liberated hydrocarbons to the interior space of the reactor drum for a total residence time, the total residence time being between 100% and 1,000% of the particle residence time.

19. The method of claim 11 , wherein cracking the liberated hydrocarbons comprises passing the liberated hydrocarbons through a catalyst.

20. 12. The method of claim 11, wherein separating the at least one lighter hydrocarbon compound from the remainder of the heated gas stream comprises varying a temperature, a pressure, or both of the heated gas stream.

21. 12. The method of claim 11, wherein separating the at least one lighter hydrocarbon compound from the remainder of the heated gas stream comprises transitioning the at least one lighter hydrocarbon compound from a gas phase to a liquid phase.

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