Graphitization furnace

Abstract

A furnace comprising: a gravity feed reactor having: an inner tube defining an interior; a heating assembly circumferentially surrounding at least a portion of the inner tube, where the heating assembly has at least one heating element configured to apply heat to the inner tube; a housing defining at least a lower portion of a gas passage circumferentially surrounding the heating assembly; and a feed structure configured to receive a feedstock, the feed structure defining a feedstock receiving space in communication with the interior of the inner tube of the reactor, where the interior of the inner tube of the reactor is fluidly isolated from the heating assembly and the gas channel.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application Nos. 63 / 354,521 and 63 / 354,526, both filed on June 22, 2022, and U.S. Provisional Application Nos. 63 / 479,573 and 63 / 479,571, both filed on January 12, 2023. Each of these priority applications is incorporated by reference into this application. Background Art

[0003] The current supply of graphite in the United States is less than 10,000 metric tons. Given the growing market for electric vehicles among other end uses, reports indicate that demand for graphite will increase to 30,000 tons by 2030. Most existing anode-grade graphite is produced by processes that have many disadvantages. The most common thermal treatment process uses an Acheson-type furnace. Not only are these furnaces extremely dangerous due to the high risk of electric shock, they are also limited to batch processing and are labor and energy intensive. A typical Acheson-type process typically produces up to 30% of the graphitizable raw material that is discarded as landfill waste.

[0004] Similar disadvantages exist with processes used to make natural or hybrid natural / synthetic graphite. Typical acid leaching processes used to prepare natural graphite require chemical consumables and can result in significant pollution if waste streams are not adequately diverted to water treatment plants. Batch induction furnaces and continuous heat treatment processes are energy intensive and often require expensive and inefficient power supply technology and frequent component replacement. Improved methods are needed to graphitize materials suitable for many end uses, including anode-grade graphite materials. Summary of the invention

[0005] The present disclosure relates to a graphite furnace and a method of using the furnace to efficiently and cost-effectively graphitize feedstock materials by heat treatment.

[0006] Embodiments of the disclosed furnace include a gravity-fed reactor having: (a) an inner tube defining an interior; (b) a heating assembly circumferentially surrounding at least a portion of the inner tube, the heating assembly having at least one heating element configured to apply heat to the inner tube; (c) an outer shell defining at least a lower portion of a gas passage circumferentially surrounding the heating assembly; and (d) a feed structure configured to contain a feedstock, the feed structure defining a feedstock containment space in communication with the interior of the inner tube of the reactor. In one embodiment, the interior of the inner tube of the reactor is fluidly isolated from the heating assembly and the gas passage.

[0007] Also described are methods of using the furnace to convert a graphitizable feedstock into graphite, for example at high temperatures. The resulting graphite can be used in a variety of applications, including as electrodes for electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing summary of the invention and the following detailed description of the present disclosure may be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the present disclosure, the accompanying drawings show some but not all alternative embodiments. The present disclosure is not limited to the precise arrangements and means shown. The following drawings, which are incorporated into and constitute a part of the specification, help explain the principles of the present disclosure.

[0009] Figure 1 is a diagram of an exemplary embodiment of a graphitization furnace.

[0010] Figure 2 is a cross-sectional view of an embodiment of a gravity-fed reactor (including a partial cross-sectional view of an upper feed structure).

[0011] Figure 3 is a cross-sectional view of an embodiment of a feed structure and material transfer system.

[0012] Figure 4 is a diagram of an exemplary embodiment of an aftercooler assembly and a conveyor assembly.

[0013] Figure 5 is another diagram of an exemplary embodiment of an aftercooler assembly and a conveyor assembly.

[0014] Figure 6 is a diagram of an exemplary embodiment of a mass flow screw of a conveyor assembly.

[0015] Figure 7 is a diagram of an exemplary alternative embodiment of an aftercooler assembly and a conveyor assembly.

[0016] Figure 8is a photograph of the valve positioned between the outlet of the aftercooler assembly and the conveyor assembly.

[0017] Fig. 9 is a diagram of an exemplary alternative embodiment of an aftercooler assembly and a conveyor assembly.

[0018] Fig.10 is a diagram of an exemplary alternative embodiment of an aftercooler assembly and a conveyor assembly.

[0019] 11 shows a graph illustrating the temperature distribution in an exemplary embodiment of a furnace, showing highly uniform temperatures in the hot zone of the furnace (inside the inner tube of the gravity-fed reactor).

[0020] Fig.12 is a graph showing 18,650 full cell tests performed with synthetic graphite prepared with embodiments of the disclosed graphitization furnace compared to widely used synthetic graphite. (Top) Long term cycling at C / 3 constant current charge rate between 3.0 V and 4.2 V. (Bottom) High precision coulometry, which measures the coulombic inefficiency of the full cell.

[0021] Fig.13 is a diagram of an exemplary embodiment of a graphitization characterization apparatus. DETAILED DESCRIPTION

[0022] The following exemplary embodiments illustrate the present disclosure. The scope of the present disclosure and claims is not limited by the scope of the following embodiments.

[0023] Figure 1 An exemplary embodiment of a graphitization furnace is depicted in FIG. The graphitization furnace 10 includes a gravity-fed reactor 20. The gravity-fed reactor 20 may be designed to graphitize graphitizable materials at extremely high temperatures (e.g., 2000-3000° C.). The graphitizable material enters the gravity-fed reactor 20 through a feed structure 30 that defines an inner tube ( Figure 1 The raw material receiving space (40) is connected to the inner tube (not shown in the figure). The raw material is transferred to the feeding structure 30 through the raw material transfer system 50, and the raw material transfer system is in fluid communication with the raw material receiving space 40 of the feeding structure 30.

[0024] Embodiments of the feedstock transfer system 50 are designed to receive feedstock, evacuate the interior space defined by at least a portion of the feedstock transfer system 50, and backfill the interior space with an inert gas, such as argon. This ensures that ambient air does not enter the feedstock containment space (40), which in turn ensures that the atmosphere within the interior of the inner tube of the gravity feed reactor 20 remains inert during graphitization.

[0025] Various mechanisms are contemplated for feeding graphitizable material to the feedstock transfer system 50. Figure 1 In the embodiment depicted in FIG, the graphitizable material is fed to the feedstock transfer system 50 from a pneumatic tube 52, which draws the feedstock from a feedstock reservoir 54. In various embodiments, the pneumatic tube 52 and the feedstock reservoir 54 are substantially sealed or sealed from ambient air. The advantage of the pneumatic tube 52 and the feedstock reservoir 54 is that the inlet feeding system is not screw-fed.

[0026] During operation, the graphitization furnace 10 can be operated under continuous temperature conditions. In some embodiments, the material can be graphitized at a rate of up to or exceeding 15 kg / hour, wherein the graphitized material continuously exits the graphitization furnace 10. In some embodiments, the feedstock can be introduced into the graphitization furnace 10 in a continuous or batch manner. For example, in one embodiment, the graphitized material can exit the graphitization furnace 10 at the same time as the graphitizable material is fed into the graphitization furnace 10.

[0027] Figure 1 The embodiment depicted in FIG. 6 includes an aftercooler assembly 60 configured to cool the graphitized material exiting the gravity feed reactor 20. In some embodiments, the aftercooler assembly 60 may include an outlet 70 that may taper as it moves in a downward direction to reduce the diameter of the outlet 70. In some embodiments, the aftercooler assembly 60 is configured to cool the graphitized material to about 800° C.

[0028] Figure 1 Embodiments also include a conveyor assembly 80 that communicates with the outlet 70 of the aftercooler assembly 60. In some embodiments, the conveyor assembly 80 is designed to further cool the graphitized material to about 50°C. Figure 1 In the embodiment depicted in , the conveyor assembly 80 is in fluid communication with a product collection system 90, which is generally designed to collect and contain the products of the graphitization. In some embodiments, the product collection system 90 includes a HEPA certified filter to ensure that the products of the graphitization do not enter the outside atmosphere.

[0029] Figure 1 The embodiment also shows a furnace programmable logic controller and power supply 95 . Figure 1 An advantage of an embodiment is that, in addition to producing lower power losses in short low voltage power lines, it allows for much shorter processing times compared to existing systems. Figure 1 Embodiments provide a graphitization system having an unexpectedly high power factor, allowing for more efficient use of electricity and, in turn, a lower cost per kWh when compared to currently operating systems.

[0030] In contrast, existing Acheson furnaces require manual loading and unloading of powder into and from graphite crucibles, manual loading and unloading of crucibles into and from the furnace stack, and long processing times per batch (relative to Figure 1 The Acheson furnace is also operated at large temperature gradients, resulting in unpredictable quality variations. The safety of the Acheson furnace is also much lower than that of the conventional furnace. Figure 1 The embodiment depicted in .

[0031] A. Gravity-fed Reactor

[0032] The gravity feed reactor 20 (below the feed structure 30) Figure 1 A more detailed view of the embodiment is shown in Figure 2 The gravity feed reactor 20 has an inner tube 100 defining an interior 110. The reactor 20 also has a heating assembly 115 that surrounds at least a portion of the inner tube 100. The heating assembly 115 has at least one heating element that is configured to apply heat to the inner tube 100.

[0033] In some embodiments, the at least one heating element comprises at least one resistive heating element. In further embodiments, the at least one heating element comprises a plurality of heating elements positioned circumferentially around at least a portion of the inner tube 100. In a specific embodiment, the at least one heating element comprises four heating elements. In some embodiments, the at least one heating element is a graphite electrode that, when resistively heated with direct current, can bring the interior 110 to a temperature suitable for graphitization, such as up to and exceeding 3000° C. Other embodiments are also contemplated in which the heating assembly is configured for induction cooling, particularly for larger scale graphitization processes.

[0034] The gravity fed reactor 20 has an outer shell 120 defining at least a lower portion 123 of a gas passage 125 that circumferentially surrounds the heating assembly 115. In one embodiment, the outer shell 120 comprises an insulating material spaced radially outwardly from the inner tube 100. The insulating material may be graphite felt.

[0035] In one embodiment, the gas passage 125 can be configured to contain helium, while the interior 110 of the inner tube 100 can be configured to contain argon. An advantage of this embodiment is that it can avoid the use of nitrogen in the overall atmosphere of the reactor, which is prone to causing wear on reactor components. Therefore, in one embodiment, the interior 110 of the inner tube 100 is fluidly isolated from the heating assembly 115 and the gas passage 125, which allows the interior 110 to include an inert gas different from the inert gas occupying the gas passage 125.

[0036] Because graphitization requires high temperatures, in some embodiments, at least a portion or all of inner tube 100 , at least the electrode portion of heating assembly 115 , and outer shell 120 are made of graphite, which can withstand the high temperatures reached in gravity feed reactor 20 .

[0037] In one embodiment, the upper portion 102 of the inner tube 100 is not circumferentially surrounded by the heating assembly 115. In other embodiments, the gas passage 125 circumferentially surrounds at least a portion of the upper portion 102 of the inner tube 100.

[0038] B. Feeding structure

[0039] exist Figure 1 One embodiment of a feed structure 30 more generally depicted in Figure 3 The feed structure 30 includes a housing 80 and a raw material inlet 210, wherein the raw material inlet defines a raw material receiving space 40 (also Figure 1 ). The housing 80 circumferentially surrounds the feedstock inlet 210. The housing 80 also defines at least a portion of the upper portion 127 of the gas passage 125 (see Figure 2 , which shows the lower portion 123 of the gas channel 125). Figure 1-3 In one embodiment, the boundary between the upper portion 127 and the lower portion 123 of the gas passage 125 is generally defined as the point where the shell 80 of the feed structure 30 and the housing 120 of the gravity feed reactor 20 meet.

[0040] refer to Figure 2-3 In one embodiment, at least a portion of the upper portion 127 of the gas passage 125 is radially spaced apart from the inner tube 100 and the raw material inlet 210. In another embodiment, the shell 80 has an inner surface 220, the raw material inlet 210 has an outer surface 225, and the furnace 10 further includes a gas receiving space ( Figure 3 The gas receiving space is defined between the inner surface 220 of the shell 80 and the outer surface 225 of the raw material inlet 210. In one embodiment, the gas receiving space is in fluid communication with the gas channel 125.

[0041] In one embodiment, continue to refer to Figure 2-3 , the maximum inner diameter of the raw material inlet 210 is greater than the diameter of the inner tube 100. Figure 1-3 The advantage of such a design is that during operation, the graphitizable material entering the feedstock containment space 40 of the feed structure 30 will be within the thermal radiation range of the gravity feed reactor 20, and specifically the interior 110 of the inner tube 100. As part of the graphitization process, portions of the graphitizable material entering the furnace will volatilize in the interior 110 of the inner tube 100 (e.g., silicon, iron, etc.) and travel upward toward and into the feedstock containment space 40. Because the feedstock containment space 40 is significantly cooler than the interior 110 of the inner tube 100, those unwanted portions of the graphitizable material are effectively isolated by the graphitizable material in the feedstock containment space 40. Once the graphitizable material in the feedstock containment space 40 falls into the interior 110 of the inner tube 100 by gravity, the isolated portions of the graphitizable material are re-vaporized and travel upward again into the feedstock containment space 40.

[0042] Figure 1-3 This phenomenon is made possible by the unique design of the embodiment shown in , which effectively allows the graphitizable feedstock material to operate as a sacrificial cold zone to isolate unwanted vaporized material before being graphitized. This in turn avoids the problems associated with re-condensation of unwanted vaporized material onto the insulation material and other materials, ultimately allowing the furnace to operate continuously for longer periods of time, particularly relative to designs that require periodic replacement of components due to deposition of typical conductive alloys in the graphitizable material onto the components intended to be isolated.

[0043] C. Raw material transfer system

[0044] refer to Figure 1 and 3 , the furnace 10 may include a raw material transfer system 50, which is in fluid communication with the raw material receiving space 40 of the feed structure 30. In one embodiment, the raw material transfer system 50 has at least one valve 310, which is configured to prevent air from entering the raw material receiving space 40. In one embodiment, the raw material transfer system 50 includes a dual discharge valve system, which includes valve 310 in addition to the feed valve 312. The dual discharge valve system allows the graphitizable raw material to enter the raw material transfer system 50, and then the ambient air can be evacuated and backfilled with an inert gas such as argon. This ensures that the remaining interior of the furnace remains in an inert atmosphere. Therefore, in one embodiment, the raw material feed system 50 may include a negative pressure source 320, which is configured to evacuate air from within the raw material transfer system 50.

[0045] D. Aftercooler and conveyor assembly

[0046] refer to Figure 1 ,2 4, the furnace 10 can include an aftercooler assembly 60 configured to cool material exiting the inner tube 100 of the reactor 20. For example, the aftercooler assembly 60 can include an inner tube 62 that is in fluid communication with the inner tube 100 of the reactor 20. In some embodiments, the inner tube of the reactor can extend along the length of the aftercooler assembly and the length of the inner tube 62 of the aftercooler assembly.

[0047] The aftercooler assembly 60 can further include an outlet 70. In some optional embodiments, at least a portion of the outlet of the aftercooler assembly 60 can taper to reduce a cross-section (eg, diameter) of the outlet 70 while moving in a downward direction.

[0048] refer to Figure 1 and 4 In some embodiments, the furnace 10 can include a conveyor assembly 80 in communication with the outlet 70 of the aftercooler assembly 60. The conveyor assembly 80 can move the graphitized material toward a product collection system 90. The product collection system 90 can be, for example, a container configured to store the graphitized material. In an exemplary embodiment, the container of the product collection system 90 can be a HEPA-certified collection and holding container.

[0049] refer to Figure 4 In some exemplary embodiments, the conveyor assembly 80 can include a screw 82 and a conveyor housing 88. The conveyor assembly 80 can have a first end 84 and an opposite second end 86. The screw 82 can be configured to rotate to convey material through the conveyor housing 88 in a direction from the first end 84 to the second end 86.

[0050] refer to Figure 5 In some optional embodiments, the screw 82 can be a horizontal screw or an inclined screw. That is, in some embodiments, the screw 82 can extend horizontally or obliquely in the direction from the first end 84 to the second end 86. For example, in some embodiments, the screw 82 can form an angle of zero to about 45 degrees, or 0 to about 30 degrees, or 0 to about 10 degrees, or 10 to about 30 degrees with the horizontal plane. In other embodiments, the screw 82 can be horizontal.

[0051] In some embodiments, screw 82 can be a mass flow screw. Optionally, the mass flow screw can be water cooled.

[0052] refer to Figure 4 and Figure 6In some embodiments, the screw 82 may include one or more threads 405 having a pitch that gradually increases in a horizontal direction away from the reactor (e.g., from the first end 84 to the second end 86). The threads 405 may extend from the body 410 of the screw 82 to define a screw groove 412 therebetween. The screw groove 412 may have a sufficient depth (measured radially from the body 410 to the outer diameter of the threads to provide sufficient flow through the conveyor assembly 80). For example, the radial depth of the screw groove 412 may be at least 1 inch, at least 1.5 inches, at least 2 inches, at least 2.5 inches, at least 3 inches, or more.

[0053] Continue to refer Figure 4 and Figure 6 In some optional embodiments, the threads 405 of the screw 82 can have a gradually increasing diameter moving in a horizontal direction away from the reactor. That is, the threads 405 can extend radially outward from the axis of rotation of the screw 82 by a radius. The radius of the threads 405 can gradually or incrementally increase from the axis of rotation along the axis of rotation of the screw.

[0054] refer to Figure 4 In some optional embodiments, the conveyor housing 88 may have an inner diameter. That is, the conveyor housing 88 may optionally have a substantially cylindrical interior. The threads 405 of the screw 82 may have a maximum diameter. In this way, the threads 405 may have a gap between the inner diameter of the conveyor housing and the maximum outer diameter of the screw 82. The gap may be less than 3 inches, or less than 2 inches, or less than 1 inch, or less than 1 / 2 inch, or less than 1 / 4 inch. By limiting this gap, undesirable flow through the conveyor 80 may be suppressed. In other embodiments, the conveyor housing 88 and the screw 82 cooperate to define a bypass area defined by a two-dimensional surface, which extends radially from the threads 405 to the inner surface of the housing along a single pitch of the thread (a 360-degree stroke of the thread) containing the maximum outer diameter of the screw 82. The bypass area may be less than 20 square inches, 15 square inches, 12 square inches, 10 square inches, 9 square inches, 8 square inches, 7 square inches, 6 square inches, 5 square inches, 4 square inches, 3 square inches, 2 square inches, or 1 square inch.

[0055] refer to Figure 7 and Figure 8 In some optional embodiments, furnace 10 may include an integrated first valve 415 positioned between outlet 70 of aftercooler assembly 60 and conveyor assembly 80. First valve 415 may be configured to control the flow rate of material entering the conveyor assembly.

[0056] In further embodiments, the conveyor assembly 80 may include an outlet 92. The furnace 10 may include a second valve 94 configured to control the flow rate of material exiting the outlet of the conveyor assembly.

[0057] In some embodiments, the first valve 415 and / or the second valve 94 may be a rotary valve ( Figure 8 ). For example, the first valve 415 and / or the second valve 94 may include a housing and a body including a plurality of blades (e.g., eight blades) that may rotate within the housing to meter the flow through the housing. In an alternative embodiment, the first valve 415 and / or the second valve 94 may be a butterfly valve (see Figure 4 ) or knife switch.

[0058] refer to Figure 4 Optionally, the furnace 10 may include a temperature sensor 96 (e.g., a thermocouple) that is in communication with the interior of the conveyor assembly 80. The temperature sensor may be configured to determine the temperature of the graphitized material. In some optional embodiments, the temperature sensor may be configured to determine the temperature of the graphitized material at or near the outlet 92. The rate of the conveyor assembly 80 may be adjusted to control the temperature of the graphitized material exiting the outlet 92 of the conveyor assembly. In this way, the graphitized material may be sufficiently cooled to be contained in the product collection system 90. In further embodiments, the temperature sensor 64 may be disposed at or near the outlet 70 of the aftercooler assembly 60. After the thermocouple reaches a sufficiently low temperature (e.g., equal to or less than about 50° C.), the valve 94 ( Figure 7-8 ) can deliver the graphitized material to the conveyor assembly 80. In some embodiments, this can avoid damaging the conveyor assembly 80.

[0059] For example, the temperature sensor 96 can communicate with a computing device (e.g., a PLC). The computing device can be configured to adjust the speed of the conveyor based on the temperature measured by the temperature sensor. For example, the computing device can increase or decrease the rotation rate of the screw 82 to increase or decrease the flow through the conveyor assembly 80.

[0060] refer to Fig. 9 , in some embodiments, the conveyor assembly 80 can be omitted. For example, the furnace 10 can include a first valve 418 that meters flow from the outlet 70 of the aftercooler assembly 60. The first valve 418 can be a rotary valve. The first valve 418 can meter flow into the impingement vessel 420. The impingement vessel 420 can have an outlet 422 that communicates with a container 426. In other embodiments, a second valve 424 (e.g., a knife gate) can selectively discharge flow from the impingement vessel 420 to the container 426.

[0061] refer to Fig.10 In further embodiments, the aftercooler assembly 60 may include a heat exchanger 419 (eg, a water cooler) configured to remove thermal energy, and therefore material, from the aftercooler assembly.

[0062] In some embodiments, most or all components of a graphitization furnace that are exposed to high temperatures (eg, 800-3000° C.) may be made of graphite.

[0063] E. Raw materials

[0064] The feedstock for the graphitization furnace can be any graphitizable material. Examples include needle coke (a petroleum-derived coke), natural graphite, other graphite materials, carbonaceous powders (e.g., 10-300 microns), carbon black (including carbon black with particle sizes up to several millimeters in diameter), other powdered carbon blacks, lignite, hard coal, certain plastics, and commercial needle petroleum coke. The process using a graphitization furnace can produce high purity (in some cases, purity exceeding 99.99%) flaky graphite. The graphitized material can be used in a variety of useful applications, including as electrodes for electric vehicles.

[0065] F. Graphite Characterization Device

[0066] A sampling device for characterizing graphitized material is also described. The sampling device is suitable for use with any embodiment of the disclosed graphitization furnace or any other graphitization reactor. In general, the sampling device uses a fixed focus optical alignment system for material characterization, which can be any such system, such as a Raman-based microscope system. In one embodiment, the disclosed graphitization reactor (or any other graphitization reactor) may further include an optical sampling device, which is configured to measure properties of the material after the graphitized material passes through the reactor. The controller can be configured to receive an input indicative of a measured property of the graphitized material. In other embodiments, the controller can be configured to modify the operation of the disclosed furnace (or any other reactor) based on the measured property of the graphitized material.

[0067] Fig.13An exemplary embodiment of a sampling device is depicted. The sampling device 500 generally includes a body 520 that defines a sample holding space 530. The sample holding space 530 can be in communication with a sample collection port 540. The sample holding space 530 can include a sample support surface 550. The sampling device 500 also includes a fixed focus optical alignment system 560 for measuring characteristics of an input material stream, such as graphitized material from a furnace. The optical alignment system 560 can include, for example, a Raman-based system, such as a confocal Raman microscope system. The sample collection port 540 (a, b) can be configured to receive a sample from a material stream 580 (e.g., a graphitized material) and allow the sample to be delivered to a sample support surface 550 within the sample holding space 530, and the optical alignment system 560 can be configured to measure characteristics of the sample when the sample is supported on the sample support surface 550 (e.g., measuring the degree of graphitization by spectroscopic methods).

[0068] exist Fig.13 In another embodiment of the present invention, the sampling device 500 includes a sample collecting tube 600, which is connected to the body 520 and extends outward from the body, and the body defines a sample receiving space 530. The sample collecting tube 600 can have an internal space 620 that is connected to the sample receiving space 530 of the body 520, so that the collecting tube 600 is connected to or defines the sample collecting port 540a. Fig.13 In the embodiment shown in , the sample collection tube 600 can be selectively moved to a collection position, in which case the sample collection tube can be rotated by a rotary actuator 650 connected to the sample collection tube 600, in which collection position a portion of the sample collection port 540b is positioned to receive a sample from the material flow 580 and allow the material to pass into the sample receiving space 530 and onto the sample support surface 550.

[0069] In some embodiments, the rotary actuator 650 can be configured to rotate the entire sample collection tube 600. In this embodiment, the rotary actuator 650 can rotate the sample collection tube 600 so that the sample collection port 540b is positioned to receive a sample from the material flow 580 (e.g., graphitized material). The sample collection tube 600 can be configured so that the material entering the sample collection port 540b can flow along the material flow axis (e.g., by gravity or any other physical or mechanical mechanism) toward the sample receiving space 530 and only toward the sample support surface 550.

[0070] In some embodiments, the material flow 580 moves in a first direction along the material flow axis, wherein in the collection position, the sample collection port 540 of the sample collection tube 600 is positioned upstream of the sample receiving space 530 of the body 520 along the material flow axis, for example, the material 580 can flow downward into the sample receiving space 530 by gravity. In one embodiment, the first direction is a downward direction, wherein the material flow axis is a vertical axis. Therefore, in the sample collection position, the sample collection port 540b of the sample collection tube 600 is positioned above the sample receiving space 530 of the body 520 along the vertical axis. In one embodiment, when the material 580 for sampling flows downward toward the sample collection tube 600, the sample collection port 540b of the sample collection tube 600 faces an upward direction along the vertical axis. Generally speaking, once the sample is collected, the rotary actuator 650 can return the sample collection tube 600 to the closed position so that the material can no longer enter the sample collection port 540b.

[0071] In another embodiment, the rotary actuator 650 can be configured to cause only the distal portion ( Fig.13 The sample collection tube 600 is rotated to return the sample collection tube 600 to the open or receiving position, while another portion of the sample collection tube (also not shown) near the device body 520 remains stationary. Other embodiments are also contemplated; for example, the sample collection tube 600 can remain stationary, and any portion of the sample collection port 540 (a, b) can be selectively opened or closed to allow the sample to enter the sample receiving space 530 and reach the sample support surface 550.

[0072] In further embodiments, the device 500 may include a plunger 700 that is selectively movable within the sample receiving space 530. In one embodiment, the plunger 700 may define a sample support surface 550. In further embodiments, the device 500 may further include a compression structure 720 positioned within the sample receiving space 530 of the body 520 between the plunger 700 and the fixed focus optical alignment system 560, such that the compression structure 720 is selectively movable between an open position 725 and a closed position 730. In the closed position 730, the compression structure 720 does not allow the sample to pass through and is configured to cooperate with the plunger 700 to compress the sample when the plunger 700 is advanced toward the fixed focus optical alignment system 560. In some embodiments, the compression structure 720 may include an actuation block or a baffle.

[0073] In further embodiments, the body 520 may define a sample outlet port 800 in communication with the sample holding space 530. In other embodiments, the body 520 defines at least one purge port (801a, 801b) positioned between the sample outlet port 800 and the fixed focus optical alignment system 560. The at least one purge port (801a, 801b) may be configured to receive gas flowing through the sample holding space 530 so that the sample exits the sample holding space 530 through the sample outlet port 800. In another embodiment, the device may further include a shielding structure positioned within the sample holding space 530 of the body 520 between the plunger 700 and the fixed focus optical alignment system 560. The shielding structure may be selectively movable between an open position and a closed position, such that in the closed position, the shielding structure does not allow the sample to pass therethrough and is configured to direct gas entering the at least one purge port (801a, 801b) toward the sample outlet port 800.

[0074] As described above, the graphite characterization device can be part of a system including the above-described graphitization furnace or any suitable graphitization reactor. The sampling device can be configured such that a collection port of the sampling device is positioned to receive a sample from a material stream generated by the disclosed graphitization furnace or any suitable graphitization reactor. It is specifically contemplated that the reactor can be any embodiment of a gravity-fed reactor of the disclosed graphitization furnace.

[0075] Also described are methods comprising performing a reaction in a reactor to produce a flow of material (e.g., graphitized material); and receiving a sample from the flow of material in a sample collection port of a sampling device. In one embodiment, the reaction can be a graphitization reaction. In other embodiments, the reactor can be a gravity feed reactor of the disclosed graphitization furnace.

[0076] The features and advantages of the present disclosure are apparent from the detailed description, and the claims cover all such features and advantages. For those skilled in the art, there will be many changes, and any changes equivalent to those described in the present disclosure fall within the scope of the present disclosure. It will be appreciated by those skilled in the art that the concepts upon which the present disclosure is based can be used as a basis for the design of other methods and systems for performing the several purposes of the present disclosure. Therefore, the claims should not be considered to be limited by the description or examples.

Claims

1. A furnace comprising: A gravity fed reactor, the gravity fed reactor having: an inner tube defining an interior; a heating assembly circumferentially surrounding at least a portion of the inner tube, wherein the heating assembly has at least one heating element configured to apply heat to the inner tube; an outer shell defining at least a lower portion of a gas passage circumferentially surrounding the heating assembly; as well as a feed structure configured to receive a raw material, the feed structure defining a raw material receiving space communicating with the interior of the inner tube of the reactor, Wherein the interior of the inner tube of the reactor is fluidly isolated from the heating assembly and the gas passage.

2. The furnace of claim 1, wherein the inner tube has an upper portion that is not circumferentially surrounded by the heating assembly, and wherein the gas passage circumferentially surrounds at least a portion of the upper portion of the inner tube.

3. A furnace according to claim 1 or claim 2, wherein the feed structure comprises a shell and a raw material inlet defining the raw material receiving space, wherein the shell circumferentially surrounds the raw material inlet, and wherein the shell defines at least a portion of an upper portion of the gas channel.

4. The furnace of claim 3, wherein at least a portion of the upper portion of the gas passage is spaced radially outward from the inner tube and the feedstock inlet.

5. The furnace of claim 3 or claim 4, wherein the shell has an inner surface, wherein the feedstock inlet has an outer surface, wherein the furnace further comprises a gas containment space defined between the inner surface of the shell and the outer surface of the feedstock inlet, and wherein the gas containment space is in fluid communication with the gas channel.

6. The furnace of any preceding claim, wherein the at least one heating element comprises at least one resistive heating element.

7. The furnace of any one of the preceding claims, wherein the at least one heating element comprises a plurality of heating elements positioned circumferentially around the at least a portion of the inner tube.

8. The furnace of claim 7, wherein the plurality of heating elements comprises four heating elements.

9. The furnace of any one of the preceding claims, wherein the outer shell comprises insulating material, and wherein the insulating material is spaced radially outwardly from the inner tube.

10. The furnace according to any one of claims 3 to 9, wherein the maximum inner diameter of the feedstock inlet is greater than the diameter of the inner tube.

11. The furnace of any one of the preceding claims, further comprising a feedstock transfer system in fluid communication with the feedstock receiving space of the feed structure.

12. The furnace of claim 11, wherein the feedstock transfer system comprises at least one valve configured to prevent air from entering the feedstock containment space.

13. The furnace of claim 12, wherein the feedstock transfer system comprises a negative pressure source configured to evacuate air from within the feedstock transfer system.

14. The furnace of any one of the preceding claims, further comprising an aftercooler assembly configured to cool material exiting the inner tube of the reactor.

15. The furnace of claim 14, wherein the aftercooler assembly comprises an inner tube in fluid communication with the inner tube of the reactor.

16. The furnace of claim 14, wherein the inner tube of the reactor extends along the length of the aftercooler assembly and the length of the inner tube.

17. The furnace of any one of claims 14 to 16, wherein the aftercooler assembly further comprises an outlet.

18. The furnace of claim 17, wherein at least a portion of the outlet of the aftercooler assembly tapers to reduce a diameter of the outlet when moving in a downward direction.

19. The furnace of claim 17 or claim 18, further comprising a conveyor assembly in communication with the outlet of the aftercooler assembly.

20. The furnace of claim 19, wherein the conveyor assembly comprises a horizontal or inclined screw.

21. The furnace of claim 20, wherein the screw is a mass flow screw.

22. The furnace of claim 21 wherein the mass flow screw is water cooled.

23. The furnace of any one of claims 20 to 22, wherein the screw comprises threads having a pitch that increases moving horizontally away from the reactor.

24. The furnace of claim 23, wherein the flights of the screw have a diameter that increases progressively moving away from the reactor in the horizontal direction.

25. The furnace of claim 23 or claim 24, wherein the flights of the screw have a maximum outer diameter, wherein the conveyor assembly further comprises a conveyor housing, the screw being housed within the conveyor housing, wherein the conveyor housing has an inner diameter, and wherein the clearance between the inner diameter of the conveyor housing and the maximum outer diameter of the screw is less than 20 square inches, 15 square inches, 12 square inches, 10 square inches, 9 square inches, 8 square inches, 7 square inches, 6 square inches, 5 square inches, 4 square inches, 3 square inches, 2 square inches, or 1 square inch.

26. The furnace of any one of claims 20 to 25, wherein the screw is a horizontal screw.

27. The furnace of any one of claims 20 to 25, wherein the screw is inclined at an angle of less than 10 degrees.

28. The furnace of any one of claims 20 to 27, further comprising a first valve positioned between the outlet of the aftercooler assembly and the conveyor assembly, wherein the first valve is configured to control a flow rate of material entering the conveyor assembly.

29. The oven of any one of claims 20 to 28, wherein the conveyor assembly comprises an outlet, and wherein the oven further comprises a second valve configured to control a flow rate of material exiting the outlet of the conveyor assembly.

30. The furnace of any one of the preceding claims, wherein the reactor comprises at least one temperature sensor, and wherein the furnace further comprises a controller communicatively coupled to the at least one temperature sensor of the reactor.

31. The furnace of claim 30, wherein the controller is configured to modify operation of the furnace based on a temperature detected by the at least one temperature sensor of the reactor.

32. A furnace as claimed in claim 30 or claim 31, wherein the reactor further comprises a confocal Raman microscope configured to measure a property of the material after it has passed through the reactor, and wherein the controller is configured to receive an input indicative of the measured property of the material.

33. The furnace of claim 32, wherein the controller is configured to modify operation of the furnace based on the measured property of the material.

Images