Patent Description:
Industrial centrifuges may be used to extract one or more chemicals from a mixture of botanical (plant) matter. In one botanical product extraction application, an industrial centrifuge can be used in a cold chemical extraction of cannabidiol (CBD) oil droplets from biomass comprised of industrial hemp or certain low-THC strains of marijuana. Typically, cold chemical extraction is conducted at low temperatures, such as around -<NUM> (-<NUM> °F), in the presence of an extraction fluid. The extraction fluid extracts the CBD oil droplets, which are carried by the extraction fluid and separated from the biomass by centrifugal force. <CIT> discloses a centrifuge. <CIT> discloses a water purification device.

Exposure of the various bearings of the industrial centrifuge to the extraction fluid may cause damage to the bearings or a motor of the industrial centrifuge. This disclosure relates to an air seal for a spindle bearing assembly of an industrial centrifuge to prevent the extraction fluid from leaking into the spindle bearing assembly, the motor bearing assembly, or both. Reducing or preventing exposure of the bearing assemblies to the extraction fluid may reduce or prevent damage to the spindle bearing assembly, the motor bearing assembly, the motor, or combinations of these. The air seal may further allow more cost effective bearings to be used in place of sealed bearings constructed of materials acceptable for use with extraction centrifuges operating with - <NUM> °F cooled extraction fluids. The air seal may be passive, driven only by the gravitation force of the extraction fluid compressing the air trapped in a chamber containing the bearing assembly.

The invention is defined by the subject-matter of the appended claims. In one or more aspects of the present disclosure, a centrifuge basket for an industrial centrifuge for extracting compounds from biomass includes a sidewall comprising an upper perforated portion and a lower solid portion, where the sidewall is cylindrical and the lower solid portion does not include perforations. The centrifuge basket may further include a basket baseplate coupled to an inner surface of the sidewall between the upper perforated portion and the lower solid portion. The centrifuge basket may further include a spindle attachment assembly coupled to the basket baseplate. The lower solid portion of the sidewall, a bottommost surface of the basket baseplate, and a housing of the spindle attachment assembly may define a skirted volume operable to form an air seal between an extraction fluid and one or more bearings during operation of the industrial centrifuge.

In one or more other aspects of the present disclosure, an industrial centrifuge for extracting compounds from biomass comprises a centrifuge basket disposed within a cylindrical vessel. The centrifuge basket comprises a sidewall comprising an upper perforated portion and a lower solid portion, where the sidewall is cylindrical. The centrifuge basket may further include a basket baseplate coupled to an inner surface of the sidewall between the upper perforated portion and the lower solid portion. The centrifuge basket may further include a spindle coupled to the basket baseplate and operatively coupled to a drive mechanism operable to rotate the spindle about an axis. The centrifuge basket further comprise a spindle bearing assembly coupled to the cylindrical vessel and disposed between a bottom of the cylindrical vessel and the basket baseplate; and a contact seal disposed between the spindle bearing assembly and the basket baseplate; wherein: the spindle passes vertically through the spindle bearing assembly and extends vertically downward to the drive mechanism disposed vertically below the bottom of the cylindrical vessel. The lower solid portion of the sidewall, a portion of the spindle, and the basket baseplate define a skirted volume wherein at least a portion of the spindle bearing assembly is disposed within the skirted volume. During operation of the industrial centrifuge, air trapped within the skirted volume provides an air seal between an extraction fluid in the cylindrical vessel and the contact seal. The air seal may reduce or prevent exposure of the contact seal and portions of the spindle bearing assembly to extraction fluids contained in the cylindrical vessel during operation.

In one or more other aspects of the present disclosure, a centrifuge basket for an industrial centrifuge for extracting compounds from biomass comprises a sidewall comprising an upper perforated portion and a lower solid portion, where the sidewall is cylindrical and the lower solid portion does not include perforations. The centrifuge basket further comprise a basket baseplate coupled to an inner surface of the sidewall between the upper perforated portion and the lower solid portion and wherein the lower solid portion of the sidewall and a bottommost surface of the basket baseplate define a skirted volume operable to form an air seal between an extraction fluid and one or more bearings during operation of an industrial centrifuge comprising the centrifuge basket. When the cylindrical vessel is filled with extraction fluid, an air bubble is formed in the skirt extension region underneath the basket baseplate. The air bubble acts as an air seal for the spindle bearing assembly protecting it from exposure to extraction fluid.

The present application is directed to methods and seals for reducing or preventing damage to bearings of industrial centrifuges caused by exposure of spindle bearings, motor bearings, or both to the extraction fluid. In particular, the present disclosure is directed to industrial centrifuges having a centrifuge basket and spindle bearing assembly that create an air seal capable of preventing exposure of the spindle bearing, the motor bearing, or both to the extraction fluid, thereby, reducing the potential for damage to the spindle bearing, motor bearing, or both.

Sealing bearings, such as rotating shaft ball and roller bearings, against wet environments can be challenging. Three different types of ball bearings can be identified: open bearings (where the balls and ball races are exposed); shielded bearings; and sealed bearings. Open bearings, such as open ball bearings, are the most cost efficient bearings and are bearings in which the balls bearings and ball races are exposed, which may allow fluids, solid debris, or both to contact the balls and ball races. In the case of open bearings in an industrial extraction centrifuge, the balls and ball races are open to exposure to the extraction fluid, which can cause damage to the balls and ball races.

Shielded bearing can include one or more shields to protect the balls and ball races. Shields are metallic discs connected to the outer bearing race, with no contact between the shield bore and the bearing inner race. Shielded bearings may prevent solid debris and some liquids from penetrating into the bearing but do not completely prevent liquids from reaching the balls and ball races.

Sealed bearings may include one or more fluid seals, which may be constructed from various elastomeric materials and may be in contact with the shaft itself. The type of fluid seal material selected can depend on compatibility with environmental factors such as the fluid composition, viscosity, temperature, and fluid hydraulic pressure. Mechanical factors such as whether the shaft is sliding (as in a hydraulic cylinder) or rotating (as in a pump or centrifuge), and the shaft surface speed can also influence selection of the seal type.

Certain companies such as A. Chesterton of Groveland, Massachusetts specialize in rotating shaft sealing solutions, which are largely used in pumps and valves. Shaft seals range from simple elastomer lip seals to complex rotating face seal assemblies. Seals acceptable for use with extraction centrifuges operating with -<NUM> (-<NUM> °F) cooled extraction fluids, such as alcohols or aliphatic solvents, are complicated. The primary technical problem is finding an elastomer that is still elastic at -<NUM> and is not degraded by exposure to organic solvents such as but not limited to ethanol, heptane, or other extraction fluid. Functional motor bearing seal assemblies for industrial centrifuges which are useable in contact with -<NUM> cooled extraction fluids such as ethanol or heptane, therefore, cost many thousands of dollars.

The present disclosure is directed to an air seal for the spindle bearings of the spindle bearing assembly, the motor bearings, or both of an industrial centrifuge for cold solvent extraction. The air seal of the present disclosure can prevent contact between the rotating spindle, motor, and/or static spindle bearing seal and the extraction fluid, which can be -<NUM> ethanol or heptane in a chemical extraction centrifuge. Other extraction fluids suitable for cold temperature extractions are also contemplated.

The air seal is created by forming an air bubble disposed between the seal surface and the extraction fluid interface. The air bubble may be formed under the centrifuge base plate, as will be described further in the present disclosure. In particular, the centrifuge base plate and a lower solid portion of a sidewall of the centrifuge basket may define a skirted volume that is airtight. The spindle bearing of the rotating spindle supporting the centrifuge basket may be arranged to always be within the air bubble formed within the skirted volume defined underneath the centrifuge baseplate. Only the air in the air bubble contacts the spindle bearing, motor bearings, or both. Thus, the air in the air bubble separates the spindle bearings, motor bearings, or both from the extraction fluid. The air seal may allow simpler, commercially available rotary non-fluid resistant bearing seals to be used, such as lip or face seals. These standard seals cost a small fraction of the price of custom fluid-resistant bearing seal assemblies usable in contact with -<NUM> pure ethanol or heptane extraction fluids.

<FIG> and <FIG> show an industrial centrifuge <NUM> for chemical extraction of the present disclosure. An example of the industrial centrifuge <NUM> for conducting chemical extractions is a Western States Machine Company model C40 botanical extraction centrifuge designed and manufactured for OEM sale, although the industrial centrifuge <NUM> is not intended to be limited thereto. Referring to <FIG>, the industrial centrifuge <NUM> includes a cylindrical vessel <NUM>, which may be referred to as a curb. The cylindrical vessel <NUM> may be coupled to the machine floor <NUM>. The machine floor <NUM> may form a bottom of the cylindrical vessel <NUM>. In embodiments, the cylindrical vessel <NUM> may have a separate curb baseplate <NUM> (<FIG>) coupled to the cylindrical vessel <NUM>, where the curb baseplate <NUM> is then coupled to the machine floor <NUM>. Referring to <FIG>, the industrial centrifuge <NUM> may include a control panel <NUM>, which may be communicatively coupled to a motor <NUM>. Referring to <FIG>, the cylindrical vessel <NUM> or curb may include a lid <NUM> that may be removable and sealable to the cylindrical vessel <NUM>. The lid <NUM> may be removed to add biomaterial to the industrial centrifuge <NUM>. The lid <NUM> may include one or more inlet pipes <NUM> that enable introduction of extraction fluids or other materials into the cylindrical vessel <NUM>. The cylindrical vessel <NUM> may further include one or more outlet pipes <NUM> from which extraction fluids and extracted materials can be withdrawn from the cylindrical vessel <NUM>.

Referring again to <FIG>, the industrial centrifuge <NUM> includes a centrifuge basket <NUM> disposed within the cylindrical vessel <NUM>. The centrifuge basket <NUM> may be a rotating cylindrical centrifuge basket in which chemical extraction from the rotating biomass takes place. The centrifuge basket <NUM> may be rotatable relative to the cylindrical vessel <NUM>. The centrifuge basket <NUM> may be rigidly coupled to a spindle <NUM>. The centrifuge basket <NUM> may be driven by the spindle <NUM>, which may be connected by a timing belt <NUM> to an electric motor <NUM> disposed below the raised machine floor <NUM>. Although shown as having a timing belt <NUM>, it is understood that the electric motor <NUM> may be operatively coupled to the spindle <NUM> through other types of linkages. The industrial centrifuge <NUM> may include the control panel <NUM> for operation of the centrifuge <NUM> and emergency stop button <NUM>, which are both located at the upper right in <FIG> and <FIG>. The industrial centrifuge <NUM> may further include castors <NUM> for easily moving the industrial centrifuge <NUM> between locations.

Referring now to <FIG>, a cross-sectional view of one embodiment of a centrifuge basket <NUM> is schematically depicted. The centrifuge basket <NUM> may include a sidewall <NUM>, a reinforcing ring <NUM> coupled to the top of the sidewall <NUM>, and the basket baseplate <NUM>. The centrifuge basket <NUM> may further include a spindle attachment assembly <NUM> coupled to the basket baseplate <NUM> of the centrifuge basket <NUM>. The sidewall <NUM> may be cylindrical and may be vertically with the center axis A of the cylindrical sidewall <NUM> parallel to the +/-Z direction of the coordinate axis in <FIG>. The sidewall <NUM> may include an upper perforated portion <NUM> and a lower solid portion <NUM>. The upper perforated portion <NUM> may have a plurality of perforations <NUM> spaced apart across the upper perforated portion <NUM>. The lower solid portion <NUM> of the sidewall <NUM> may not have perforations. The upper perforated portion <NUM> and the lower solid portion <NUM> of the sidewall <NUM> of the centrifuge basket may be demarcated by a horizontal plane P (e.g., a plane perpendicular to the +/-Z direction of the coordinate axis in <FIG>) that is tangent to a bottom of the perforations <NUM> the bottom most row <NUM> of perforations <NUM>. The bottom most row <NUM> of perforations <NUM> may be the horizontal row of perforations <NUM> around the circumference of the centrifuge basket <NUM> that has a vertical position (e.g., position in the +/-Z direction of the coordinate axis in <FIG>) lower than any of the other rows of perforations <NUM> (e.g., positioned in the -Z direction relative to all the other perforations <NUM>).

The sidewall <NUM> of the centrifuge basket <NUM> may be formed by perforating a portion of a flat metal sheet to create the upper perforated portion <NUM>. The partially perforated flat metal sheet may then be rolled into a cylindrical shape and the ends of the partially perforated metal sheet may then be welded together along a seam <NUM> to produce the sidewall <NUM> of the centrifuge basket <NUM> having a cylindrical shape. The top edge of the sidewall <NUM> may then be welded to the edges of the reinforcing ring <NUM>.

The centrifuge basket <NUM> may further include a basket baseplate <NUM>, which may be a disk-shaped plate. The basket baseplate <NUM> may be coupled/welded to the sidewall <NUM> between the upper perforated portion <NUM> and the lower solid portion <NUM> of the sidewall <NUM>. The basket baseplate <NUM> may be oriented horizontally such that a center plane C of the basket baseplate <NUM> is perpendicular to the +/-Z direction of the coordinate axis in <FIG>. The basket baseplate <NUM> may have a bottommost surface <NUM> and an outer radial edge <NUM>. The basket baseplate <NUM> may be coupled to the sidewall <NUM> so that an outer radial edge <NUM> of the basket baseplate <NUM> is connected to the inner surface <NUM> of the sidewall <NUM>.

Referring to <FIG>, the basket baseplate <NUM> is positioned within the cylindrical sidewall <NUM> between the upper perforated portion <NUM> and the lower solid portion <NUM> of the sidewall <NUM>, such as just below the bottom of the upper perforated portion <NUM> so that no perforations of the sidewall <NUM> are below the level of the basket baseplate <NUM>. Referring now to <FIG>, the basket baseplate <NUM> may be positioned relative to the sidewall <NUM> so that the center plane C of the basket baseplate <NUM> is vertically below (e.g., in the -Z direction of the coordinate axis in <FIG>) the horizontal plane P tangent to a bottom of the perforations <NUM> the bottom most row <NUM> of perforations <NUM>. The basket baseplate <NUM> may be positioned relative to the sidewall <NUM> so that at least a portion of the lower solid portion <NUM> of the sidewall <NUM> extends below the basket baseplate <NUM>. In embodiments, the basket baseplate <NUM> may be positioned relative to the sidewall <NUM> so that the center plane C of the basket baseplate <NUM> is vertically above (e.g., in the +Z direction of the coordinate axis in <FIG>) the bottommost end <NUM> of the sidewall <NUM>. In embodiments, the basket baseplate <NUM> is positioned relative to the sidewall <NUM> such that the bottom most surface <NUM> of the basket baseplate <NUM> is vertically above (e.g., in the +Z direction of the coordinate axis in <FIG>) and spaced apart from the bottommost end <NUM> of the sidewall <NUM>. The lower solid portion <NUM> of the sidewall <NUM> extending below the basket baseplate <NUM> does not include any perforation or holes. Referring now to <FIG>, the disk-shaped basket baseplate <NUM> may be coupled/welded to the inner surface <NUM> of the sidewall <NUM> along an inner cylinder circumference <NUM> between the upper perforated portion <NUM> and the lower solid portion <NUM> of the sidewall <NUM>.

The basket baseplate <NUM> may be coupled to the inner surface of the sidewall <NUM> in a manner that prevents penetration of extraction fluid between the basket baseplate <NUM> and the inner surface of the sidewall <NUM>. The basket baseplate <NUM> may be coupled, such as welded, to the sidewall <NUM> so that the basket baseplate <NUM> is sealed against the sidewall <NUM> to prevent liquids or gases from passing through the joint between the basket baseplate <NUM> and the sidewall <NUM>. The joint coupling the basket baseplate <NUM> to the sidewall <NUM> is air tight in order for the basket baseplate <NUM> and lower solid portion <NUM> of the sidewall <NUM> to form an air bubble without allowing air to escape the bubble or extraction fluid to infiltrate the bubble through the joint.

Referring again to <FIG>, the basket baseplate <NUM> may comprise the sealed basket floor of the centrifuge basket <NUM>. The basket baseplate <NUM> may be a solid circular plate having a topmost surface <NUM> and the bottommost surface <NUM>. The basket baseplate <NUM> may have a hole in the center to receive a spindle attachment assembly <NUM>. The sealed spindle attachment assembly <NUM> may be welded to the basket baseplate <NUM>. In embodiments, the spindle attachment assembly <NUM> is disposed in the hole in the basket baseplate <NUM> and welded or otherwise coupled thereto.

The spindle attachment assembly <NUM> may include a housing <NUM> and a solid cover <NUM>. The basket baseplate <NUM> may have a center opening, and the housing <NUM> of the spindle attachment assembly <NUM> may be disposed within the opening and coupled to the basket baseplate <NUM>, as indicated previously herein. In embodiments, the basket baseplate <NUM> may be welded to the housing <NUM> of the spindle attachment assembly <NUM> with one or more welds <NUM>. The spindle attachment assembly <NUM> may be coupled to the basket baseplate <NUM> in a manner that prevents penetration of the extraction fluid between the basket baseplate <NUM> and the spindle attachment assembly <NUM>. The basket baseplate <NUM> may be coupled, such as welded, to the spindle attachment assembly <NUM> so that the basket baseplate <NUM> is sealed against the spindle attachment assembly <NUM> to prevent liquids or gases from passing through the joint between the basket baseplate <NUM> and the spindle attachment assembly <NUM>. The joint coupling the basket baseplate <NUM> to the spindle attachment assembly <NUM> may be air tight in order for the basket baseplate <NUM> and lower solid portion <NUM> of the sidewall <NUM> to form an air bubble without allowing air to escape the bubble or extraction fluid to infiltrate the bubble through the joint between the basket baseplate <NUM> and the spindle attachment assembly <NUM>.

Referring again to <FIG>, in embodiments, a solid cover <NUM> may be attached to the housing <NUM> of the spindle attachment assembly <NUM>. The solid cover <NUM> may seal the rotating spindle <NUM> (<FIG> and <FIG>) from the extraction fluid in the centrifuge basket <NUM> during operation of the industrial centrifuge <NUM>. The spindle attachment assembly <NUM> may be rigidly attached to the motor drive spindle <NUM>.

In one type of chemical extraction centrifuge, the cylindrical centrifuge basket <NUM> may spin reversibly at rotational speeds of up to approximately <NUM> rotations per minute (RPM). However, in some embodiments, the industrial centrifuge <NUM> of the present disclosure may be operated at rotational speeds of greater than <NUM> RPM.

Referring now to <FIG>, the centrifuge basket <NUM> is mounted inside the cylindrical vessel <NUM> (curb), which is a fluid-tight container. The cylindrical vessel <NUM>, which has an openable sealed top lid <NUM>, may be attached to a curb baseplate <NUM>, which may be further attached to the raised machine floor <NUM>. The curb baseplate <NUM> may form a bottom of the cylindrical vessel <NUM>.

The rotating spindle <NUM> may be affixed to the centrifuge basket <NUM> using the spindle attachment assembly <NUM>. The spindle <NUM> may pass through the spindle bearing assemblies <NUM> and <NUM> mounted in a bearing housing <NUM>, which may be coupled to the curb baseplate <NUM>. The bearing housing <NUM> may surround the spindle bearing assemblies. The curb baseplate <NUM> may be attached to the raised machine floor <NUM>. The spindle <NUM> may pass vertically through the spindle bearing assemblies <NUM> and <NUM> and may extend vertically downward (e.g., in the -Z direction of the coordinate axis of <FIG>) to engage with the drive mechanism disposed vertically below the curb baseplate <NUM> of the cylindrical vessel <NUM>. As used herein, the term drive mechanism may refer to the electric motor <NUM> (<FIG>) or other type of motor and any linkage between the motor <NUM> and the spindle <NUM>, such as but not limited to the timing belt <NUM> depicted in <FIG>.

Referring again to <FIG>, the industrial centrifuge <NUM> may include a simple, lip-type contact seal <NUM> disposed between the bottom of the spindle attachment assembly <NUM> and the spindle bearing assembly <NUM>. Although a lip-type contact seal <NUM> is depicted, it is understood that other types of seals, such as face seals for example, may be disposed between the bottom of the spindle attachment assembly <NUM> and the spindle bearing assembly <NUM>.

The industrial centrifuge <NUM> may include an inlet pipe <NUM> and an outlet pipe <NUM>. The inlet pipe <NUM> for the extraction fluid may enter through the top of the cylindrical vessel <NUM>, such as through the sealed top lid <NUM>. All extraction fluid may be drained out of the curb through the outlet pipe <NUM>. Both the outlet pipe <NUM> and bearing housing <NUM> may be attached and sealed to curb baseplate <NUM> in a manner that prevents leakage of the extraction fluid between the curb baseplate <NUM> and the bearing housing <NUM> and outlet pipe <NUM>.

Referring again to <FIG>, the basket baseplate <NUM>, the lower solid portion <NUM> of the sidewall <NUM> extending below basket baseplate <NUM>, and at least a portion of the spindle <NUM> define a skirted volume <NUM>. In embodiments, the skirted volume <NUM> may be defined by the basket baseplate <NUM>, the lower solid portion <NUM> of the sidewall <NUM> extending below basket baseplate <NUM>, the housing <NUM> of the spindle attachment assembly <NUM>, the lip-type contact seal <NUM>, and at least a portion of the spindle bearing assembly <NUM>. The skirted volume <NUM> may be an annular volume defined between an inner surface of the lower solid portion <NUM> of the sidewall <NUM> and the spindle <NUM>. In embodiments, the skirted volume <NUM> may be the annular volume defined between the inner surface <NUM> of the lower solid portion <NUM> of the sidewall <NUM>, the outer surfaces of the housing <NUM> of the spindle attachment assembly <NUM>, the lip-type contact seal <NUM>, the spindle <NUM>, and the spindle bearing assembly <NUM>. The skirted volume <NUM> may extend downward (i.e., in the -Z direction of the coordinate axis in <FIG>) from the bottommost surface <NUM> of the basket baseplate <NUM> to the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM>.

The skirted volume <NUM> may be initially filled with air prior to operation of the industrial centrifuge <NUM> and enables formation of an air bubble <NUM> within the skirted volume <NUM> when the extraction fluid is added to the cylindrical vessel <NUM> during operation. The air bubble <NUM> formed in the skirted volume <NUM> provides an air seal between the extraction fluid <NUM> in the cylindrical vessel <NUM> and the lip-type contact seal <NUM> disposed between the spindle attachment assembly <NUM> and the spindle bearing assembly <NUM>. The air seal created by the air bubble <NUM> may reduce or prevent contact between the extraction fluid <NUM> and the lip-type contact seal <NUM>, which may reduce or prevent intrusion of the extraction fluid <NUM> into the spindle bearing assemblies <NUM>, <NUM>.

In embodiments, at least a portion of the spindle bearing assembly <NUM> is disposed within the skirted volume <NUM> such that the portion of the spindle bearing assembly <NUM> may be contained within the air bubble <NUM> when the cylindrical vessel <NUM> is filled with extraction fluid <NUM>. At least a portion of the spindle bearing assembly <NUM> may be disposed vertically above the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM>. When the cylindrical vessel <NUM> is filled with extraction fluid <NUM> to the working level <NUM>, the volume of extraction fluid <NUM> in the cylindrical vessel <NUM> may exert hydrostatic pressure forces that may act to compress the air bubble <NUM> in the skirted volume <NUM>, which may cause the final vertical level of the extraction fluid <NUM> in the skirted volume <NUM> to be higher than the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM>. To compensate for this effect, a vertical distance d between a topmost portion of the spindle bearing assembly <NUM> and the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM> may be sufficiently large so that the air bubble <NUM> trapped by the skirted volume <NUM> contains at least a portion of the spindle bearing assembly <NUM> when the air bubble <NUM> is compressed by the extraction fluid <NUM> when filled to the working level <NUM> at the operating temperature of the industrial centrifuge <NUM>, such as a temperature of -<NUM>. In other words, the vertical distance d should be sufficient to allow the air bubble <NUM> to be compressed by the extraction fluid during filling while still maintaining a portion of the spindle bearing assembly <NUM> within the air bubble <NUM>. The vertical distance d between the topmost portion of the spindle bearing assembly <NUM> and the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM> may depend on the dimensions of the cylindrical vessel <NUM> (e.g., the height), the total volume defined by the skirted volume <NUM>, the operating temperature of the industrial centrifuge <NUM>, and the properties of the extraction fluid <NUM>.

In embodiments, at least a portion of the bearing housing <NUM> may be disposed within the skirted volume <NUM> such that the topmost portion of the bearing housing <NUM> is contained within the air bubble <NUM> when the cylindrical vessel <NUM> is filled with the extraction fluid <NUM>. At least a portion of the bearing housing <NUM> may be disposed vertically above the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM>. As previously discussed, the extraction fluid <NUM> may compress the air bubble <NUM> when the cylindrical vessel <NUM> is filled to the working level <NUM>. Thus, a vertical distance between a topmost portion of the bearing housing <NUM> and the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM> may be sufficiently large so that the air bubble <NUM> trapped by the skirted volume <NUM> contains at least a portion of the bearing housing <NUM> when the air bubble <NUM> is compressed by the extraction fluid <NUM> when filled to the working level <NUM> at the operating temperature of the industrial centrifuge <NUM>, such as a temperature of -<NUM>. In other words, the vertical distance should be sufficient to allow the air bubble <NUM> to be compressed by the extraction fluid during filling while still maintaining a portion of the bearing housing <NUM> within the air bubble <NUM>. The vertical distance between the topmost portion of the bearing housing <NUM> and the bottommost end <NUM> of the lower solid portion <NUM> of the sidewall <NUM> may depend on the dimensions of the cylindrical vessel <NUM> (e.g., the height), the total volume defined by the skirted volume <NUM>, the operating temperature of the industrial centrifuge <NUM>, and the properties of the extraction fluid <NUM>.

Referring again to <FIG>, operation of the industrial centrifuge <NUM> of the present disclosure will now be described. When the cylindrical vessel <NUM> is empty of extraction fluid <NUM>, then the cylindrical vessel <NUM> may be temporarily opened by opening the sealed top lid <NUM>, and the biomass (not shown) from which one or more chemicals, such as but not limited to CBD, is to be extracted may then be placed within the centrifuge basket <NUM> disposed in the cylindrical vessel <NUM>. The sealed top lid <NUM> may then be closed and sealed. The -<NUM> extraction fluid <NUM>, such as but not limited to ethanol, heptane, or other extraction fluids, may be introduced to the cylindrical vessel <NUM> through inlet pipe <NUM>, filling cylindrical vessel <NUM> from the curb baseplate <NUM> up to a typical working level <NUM> just above the top of the centrifuge basket <NUM>. Although not shown in <FIG>, the extraction fluid <NUM> along with the biomass fills the portion of the centrifuge basket <NUM> defined by the upper perforated portion <NUM> of the sidewall <NUM> as well. During filling of the cylindrical vessel <NUM> with the extraction fluid <NUM>, air may become trapped in the skirted volume <NUM> by the increasing level of extraction fluid <NUM>. Thus, an air bubble <NUM> may form in the skirted volume <NUM> defined underneath the centrifuge basket baseplate <NUM>. This air bubble <NUM> may be slightly compressed air at the extraction fluid temperature of -<NUM>. The length and diameter of the lower solid portion <NUM> of the sidewall <NUM> of the centrifuge basket <NUM> may determine the size of the air bubble <NUM> and the fluid exclusion volume, which is the volume of extraction fluid excluded from the skirted volume <NUM> by the air bubble <NUM>.

As previously discussed, the rotating spindle attachment assembly <NUM> may be rigidly attached to the centrifuge basket <NUM>. The spindle bearing assembly <NUM> may be attached to curb baseplate <NUM>, with a lip type contact seal <NUM> attached to spindle bearing assembly <NUM>. By design, the gap between the spindle attachment assembly <NUM> and the spindle bearing assembly <NUM> may be enclosed in the air bubble <NUM> defined by the skirted volume <NUM> so that the lip-type contact seal <NUM> is positioned near the center of the air bubble <NUM>. Thus, the air bubble <NUM> may form an air seal including the lip type contact seal <NUM>, which may exclude the extraction fluid <NUM> from the spindle bearing assembly <NUM>.

Forming an air bubble <NUM> in the skirted volume <NUM> defined underneath the centrifuge basket baseplate <NUM>, as shown in <FIG>, may reduce the total volume of extraction fluid <NUM> required to fill the cylindrical vessel <NUM> to the working level <NUM> by the volume of the air bubble <NUM>. Thus, less volume of extraction fluid <NUM> may be required for operation of the industrial centrifuge <NUM>.

Claim 1:
An industrial centrifuge (<NUM>) for extracting one or more compounds from biomass, the industrial centrifuge (<NUM>) comprising:
a centrifuge basket (<NUM>) disposed within a cylindrical vessel (<NUM>), the centrifuge basket (<NUM>) comprising:
a sidewall (<NUM>) comprising an upper perforated portion (<NUM>) and a lower solid portion (<NUM>), where the sidewall (<NUM>) is cylindrical;
a basket baseplate (<NUM>) coupled to an inner surface of the sidewall (<NUM>) between the upper perforated portion (<NUM>) and the lower solid portion (<NUM>); and
a spindle (<NUM>) coupled to the basket baseplate and operatively coupled to a drive mechanism (<NUM>, <NUM>) operable to rotate the spindle (<NUM>) about an axis;
a spindle bearing assembly coupled to the cylindrical vessel (<NUM>) and disposed between a bottom of the cylindrical vessel (<NUM>) and the basket baseplate (<NUM>); and
a contact seal (<NUM>) disposed between the spindle bearing assembly and the basket baseplate (<NUM>);
wherein:
the spindle (<NUM>) passes vertically through the spindle bearing assembly and extends vertically downward to the drive mechanism (<NUM>, <NUM>) disposed vertically below the bottom of the cylindrical vessel (<NUM>);
the lower solid portion (<NUM>) of the sidewall (<NUM>), a portion of the spindle (<NUM>), and the basket baseplate (<NUM>) define a skirted volume (<NUM>);
at least a portion of the spindle bearing assembly is disposed within the skirted volume (<NUM>); and
during operation of the industrial centrifuge (<NUM>), an air bubble (<NUM>) trapped within the skirted volume (<NUM>) provides an air seal between an extraction fluid in the cylindrical vessel (<NUM>) and the contact seal (<NUM>).