Patent Publication Number: US-2019184310-A1

Title: Method for recovering solvent from biomass

Description:
FIELD 
     This disclosure relates to methods for recovering solvent from biomass. More specifically, this disclosure relates to methods for recovering solvent from biomass during an essential oil extraction process. 
     BACKGROUND 
     Solvents, such as ethanol, can be used to extract essential oils from plant matter. Examples of plant matter that contain useful essential oils include lavender flowers, eucalyptus leaves, peppermint leaves, tea tree leaves, jojoba seeds, rose petals, cannabis flowers, and jasmine flowers. Essential oils are used in a wide variety of applications, including as additives in household cleansers and personal care products (e.g. shampoos, lotions, facial cleansers) and in pain relief treatments. 
     In an essential oil extraction process using a quick-wash ethanol technique, plant matter (i.e. biomass) is submerged in ethanol for a period of time. While submerged, the solvent removes essential oils from the plant matter. After the essential oils have been removed from the plant matter, the spent plant matter is removed from the solvent and discarded. The solution of solvent and essential oils is then processed to isolate the essential oils. 
     The spent plant matter that is removed from the solvent is typically wetted with solvent. In a small operation, such as when extracting essential oils from flowers at home, the amount of solvent remaining in the spent plant matter may be relatively small (e.g. 20 percent of the total amount of solvent used) and, consequently, of relatively little value. Therefore, it may not make economic sense to spend time and effort attempting to recover the remaining solvent from the plant matter before discarding it. However, when operating a large scale essential oil extraction process, where many large batches of plant matter are processed every hour and large volumes of solvent are used (e.g. to extract essential oils for large batches of personal care products, such as perfumes or shampoos), it can be desirable to spend time and effort recovering solvent from the spent plant matter for reuse. By recovering as much solvent as possible, the process operator reduces the amount of solvent that has to be purchased to sustain the process and also significantly reduces the amount of solvent that must be disposed of (e.g. trucked away) with the spent plant matter. 
     An apparatus is needed to increase the percentage of solvent that can be quickly, easily, and affordably recovered from spent plant matter before it is discarded during an essential oil extraction process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a front right perspective view of an apparatus for recovering solvent from biomass. 
         FIG. 2  shows a front left perspective view of the apparatus of  FIG. 1 . 
         FIG. 3  shows a perspective view of a portion of the apparatus of  FIG. 1 , including an upper press member, lower press member, and biomass receptacle supported by the lower press member. 
         FIG. 4  shows a perspective view of a portion of the apparatus of  FIG. 1 , including an upper press member, lower press member, and biomass receptacle supported by the lower press member. 
         FIG. 5  shows a bottom perspective view of a biomass receptacle with a plurality of thru holes. 
         FIG. 6  shows a bottom perspective view of a portion of the apparatus of  FIG. 1 , including an upper press member and lower press member with the biomass receptacle removed. 
         FIG. 7  shows a top perspective view of a portion of the apparatus of  FIG. 1 , including an upper press member, gas injection system, and lower press member with the biomass receptacle removed to expose a drainage opening. 
         FIG. 8  shows a top perspective view of a portion of the apparatus of  FIG. 1 , including an upper press member, gas injection system, and lower press member with the biomass receptacle removed to expose a drainage opening. 
         FIG. 9  shows a side cross-sectional view of an apparatus for recovering solvent from biomass, the apparatus in an open position with the upper press member spaced apart from the biomass receptacle. 
         FIG. 10  shows a side cross-sectional view of the apparatus of  FIG. 9 , the apparatus in a closed position with the upper press member sealed against the biomass receptacle. 
         FIG. 11  shows a step of soaking biomass in solvent to extract essential oils from the biomass. 
         FIG. 12  shows a step of transferring the biomass from the vessel containing solvent to a solvent recovery apparatus using a transfer plate. 
         FIG. 13  shows a step of placing the biomass, which is wetted with solvent, in a biomass receptacle of a solvent recovery apparatus. 
         FIG. 14  shows the steps of applying compressive force to the biomass by transitioning the apparatus from an open position to a closed position and applying gas pressure via a gas injection system. 
         FIG. 15  shows a compressed gas delivery system fluidly connected to a gas injection system of a solvent recovery apparatus. 
         FIG. 16  shows a portion of an essential oil extraction system including a dunk tank, apparatus for recovering solvent from biomass, and a conical storage vessel. 
       SUMMARY 
       In one example, a method for recovering liquid solvent from biomass can include providing a biomass receptacle containing a mixture of biomass and liquid solvent, exerting pressure on the mixture of biomass and liquid solvent while the mixture is positioned in the biomass receptacle, flowing pressurized gas through the mixture of biomass and liquid solvent while the mixture is positioned in the biomass receptacle, and collecting the liquid solvent that exits the biomass receptacle. 
       In another example, a method for recovering solvent from biomass can include providing a flexible receptacle containing biomass and liquid solvent, placing the flexible receptacle containing biomass and liquid solvent into a biomass receptacle where the biomass receptacle has a plurality of openings, pressing the flexible receptacle against the biomass receptacle and causing at least a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings in the biomass receptacle, and flowing gas through the flexible receptacle containing biomass and liquid solvent to force at least a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings in the biomass receptacle where it can be recovered. Flowing gas through the flexible receptacle can include delivering gas at a pressure of 5-100, 10-50, 15-25, or 20 psi proximate a top surface of the flexible receptacle. Flowing gas through the flexible receptacle can include delivering gas at a first pressure for a first predetermined duration and delivering gas at a second pressure for a second predetermined duration. The first pressure can be 10-25, 10-30, or 25-40 psi, and the second pressure can be 40-75, 50-100, or 75-125 psi. The first predetermined duration can be 0.5-3, 2-5, or 5-15 minutes, and the second predetermined duration can be 0.5-3, 2-5, or 5-15 minutes. The gas can be selected from a group consisting of nitrogen, argon, air, and carbon dioxide. Pressing the flexible receptacle against the biomass receptacle can include applying a pressure of 10-30, 20-50, 30-50, 40-60, 50-70, 60-80, 70-90, or 80-100 psi to the flexible receptacle. Providing the flexible receptacle can include soaking the flexible receptacle in a vessel of liquid solvent for a predetermined duration and transferring the flexible receptacle from the vessel of liquid solvent to the biomass receptacle using a transfer plate. The transfer plate can extend on a decline from the biomass receptacle to the vessel of solvent, allowing liquid solvent that drains from the flexible receptacle during the transfer process to flow on the transfer plate back into the vessel of solvent. Providing the flexible receptacle containing biomass and liquid solvent can include filling an interior bag with biomass and placing the interior bag within an exterior bag, where the exterior bag is made of a durable woven fabric. Pressing the flexible receptacle against the biomass receptacle can occurs prior to, after, or while flowing gas through the flexible receptacle. 
       In another example, a method for recovering solvent from biomass can include providing a flexible receptacle containing biomass and liquid solvent, placing the flexible receptacle of biomass and liquid solvent into a concave biomass receptacle where the concave biomass receptacle has a plurality of openings along a bottom surface of the concave biomass receptacle, pressing a convex press member against the flexible receptacle containing biomass and liquid solvent and thereby compressing the biomass and causing a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings in the concave biomass receptacle, flowing pressurized gas through the flexible receptacle of biomass and liquid solvent thereby causing a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings in the concave biomass receptacle, and collecting the liquid solvent that flows through the plurality of openings in the concave biomass receptacle. Flowing pressurized gas through the flexible receptacle of biomass and liquid solvent can include flowing gas at a pressure of 5-15, 10-25, 20-40, 30-60, 50-70, 60-80, 70-90, 80-100 psi through the flexible receptacle containing biomass and liquid solvent. Pressing the convex press member against the flexible receptacle of biomass and liquid solvent can include pressing the convex member against the flexible receptacle of biomass and liquid solvent by applying a pressure of 10-30, 20-50, 30-50, 40-60, 50-70, 60-80, 70-90, or 80-100 psi. Providing the flexible receptacle containing biomass and liquid solvent can include providing an interior bag containing the biomass and liquid solvent where the interior cotton bag is positioned within an exterior bag made of canvas. Pressing the convex press member against the flexible receptacle of biomass and liquid solvent can occur prior to, while, or after flowing pressurized gas through the flexible receptacle of biomass and liquid solvent. 
     
    
    
     DETAILED DESCRIPTION 
     Apparatuses and methods for extracting solvent from biomass are disclosed herein. In a preferred embodiment, the apparatus  100  can include a physical press configured to exert pressure on wetted plant mater to force liquid solvent from the plant matter so the solvent can be collected for reuse. The apparatus can also be configured to apply pressurized gas to the wetted plant matter, thereby passing pressurized gas through the wetted plant matter and carrying liquid solvent away from the plant matter so the solvent can be collected for reuse. Because the apparatus does not rely on heat or vacuum to recover solvent, it can be less expensive to manufacture and operate than existing solvent recovery apparatuses. 
     An apparatus  100  for recovering solvent from biomass can include a supporting frame  130 . In one example, shown in  FIGS. 1 and 2 , the frame  130  can include a first upright member  131 , a second upright member  132 , and an upper cross member  133  connecting an upper portion of the first upright member  131  to an upper portion of the second upright member  132 . The frame  130  can include a lower cross member  133  connecting a lower portion of the first upright member  131  to a lower portion of the second upright member  132 . The frame  130  can include a first stabilizing member  135  and a second stabilizing member  136  that extend outwardly to stabilize the apparatus  100  and prevent the apparatus from tipping over during use. 
     The apparatus can include a biomass receptacle  105 . An example of the biomass receptacle  105  is shown in  FIGS. 1-5 . The biomass receptacle  105  can have an inner surface  107  and an outer surface  108 . The biomass receptacle  105  can have a plurality of openings  106  passing from the inner surface to the outer surface, as shown in  FIG. 5 , to form a perforated basket. The openings  106  can be holes with diameters that are large enough to permit the liquid solvent to easily flow from the wetted biomass to the drainage surface of the lower press  115  during operation of the apparatus. However, it is also desirable for the diameters of the holes to be small enough to prevent the outer material of the flexible receptacle  160  from being drawn into the holes and potentially damaged (e.g. torn or irreversibly deformed). In some examples, the holes in the biomass receptacle  105  can have a diameter of about 0.0625-0.25, 0.125-0.375, 0.25-0.5, 0.375-0.525, 0.125, 0.25-0.5 in. In a preferred embodiment, the holes can have a diameter of about 0.25 in. The edges of the holes  106  can be sanded or polished smooth to avoid tearing the outer fabric of the flexible receptacle  160  during operation of the physical press  100  and gas injection system  150  of the apparatus. In one example, the holes  106  can be formed with a water jet and the inner surface  107  of the biomass receptacle  105  can be wet sanded or polished. In one example, as shown in  FIG. 5 , the holes  106  can be spaced apart and arranged in a uniform radial pattern to allow for uniform drainage of solvent through the biomass receptacle  105 . 
     The biomass receptacle  105  can be made of a rigid material capable of withstanding compressive force applied by components of the apparatus  100  without deflecting. In some examples, the biomass receptacle  105  can be made of a food-safe material (e.g. stainless steel) and have a thickness of at least 0.125, 0.25, 0.375, or 0.5 in and preferable about 0.375 in. The biomass receptacle  105  can have a diameter of at least 6, 12, 18, 24, or 30 in. In one example, the inner surface  107  of the biomass receptacle  105  can be curved (e.g. concave). In one example, the inner surface  107  of the biomass receptacle  105  can be hemispherical, similar to a well cap used to seal pressure vessels. Curvature of the inner surface  107  may be desirable for several reasons. First, the curved inner surface  107  may provide more uniform pressure distribution during a physical pressing step, thereby improving performance and increasing longevity of the biomass receptacle. The curved inner surface  107  may serve to self-align the biomass receptacle  105  with the upper press member (plunger)  110  during operation, thereby improving performance and reducing downtime for mechanical adjustments. The curved surface may improve solvent recovery yields by containing the solvent, utilizing gravity to recover solvent, and not allowing solvent to escape at a perimeter of the biomass receptacle, which can occur in a flat press. 
     The apparatus  100  can include an upper press member  110  and a lower press member  115  and a means for advancing the upper and lower press members toward each other to exert compressive force on biomass  400  positioned within the biomass receptacle  105 , thereby squeezing the biomass and causing solvent  300  to exit the biomass and allowing the solvent to be recovered for reuse. In the example shown in  FIG. 1 , the upper press member  110  can remain stationary, and the lower press member  115  can move toward the upper press member to a closed position. In the closed position shown in  FIG. 10 , the lower press member  115  can exert a compressive force against the upper press member  110  via the biomass receptacle  105 . In another example, the lower press member  115  can remain stationary, and the upper press member  110  can move toward the lower press member to a closed position. In yet another example, both the upper and lower press members can be movable toward each other. 
     In the example shown in  FIG. 1 , the upper press member  110  can be attached to the frame  130  of the apparatus by a rigid support member  113 . The upper press member can include an upper surface  111 , a lower surface opposite  112  the upper surface, and a rim surface  109  extending around a perimeter of the upper press member. 
     The upper press member (plunger)  110  can be made of a rigid material capable of withstanding compressive force without deflecting significantly. In some examples, the upper press member  110  can be made of a food-safe material (e.g. stainless steel) and have a thickness of at least 0.25, 0.375, or 0.5 in. The lower surface  112  of the upper press member  110  can be curved (e.g. convex). In one example, the lower surface  112  of the upper press member  110  can be hemispherical. Curvature of the lower surface  112  of the upper press member  110  may be desirable for several reasons. First, the curved lower surface  112  may provide more uniform pressure distribution thereby improving performance and increasing longevity of the upper press member  110 . The curved lower surface  112  may serve to self-align the upper press member  110  with the biomass receptacle  105  during operation, thereby improving performance and reducing downtime for mechanical adjustments. 
     The solvent recovery apparatus  100  can include a gas injection system  105  capable of delivering compressed gas to biomass  400  within the apparatus. Flowing compressed gas through the biomass can significantly improve the percentage of solvent  300  that is recovered from the wetted biomass. In a preferred example, the biomass  400  can be subjected to physical pressing first and then, while the biomass remains subjected to physical pressing, compressed gas is applied to the biomass, as shown in  FIG. 14 . The compressed gas can flow through the biomass and entrain and transport liquid solvent through the openings in the biomass receptacle, where the solvent can then be collected and reused. In another example, the wetted biomass can first be exposed to a flow of compressed gas and then be physically pressed. In another example, the wetted biomass can be exposed to a flow of compressed gas while it is being physically pressed. In still another example, the biomass  400  can be subjected to physical pressing first and then, after the pressing is complete and the press is relaxed, compressed gas can be applied to the biomass. 
     An example of a gas injection system  150  is shown in  FIGS. 1-10 . The gas injection system  150  can include a gas supply line  153 . The gas supply line  153  can be fluidly connected to a gas manifold  151 . The gas manifold  151  can be fluidly connected to a plurality of gas passageways  152  that deliver pressurized gas to corresponding gas inlets  154  in the lower surface  112  of the upper press member  110 .  FIG. 6  shows an upper press member  110  with four gas inlets  154  located equidistant from the center of the lower surface  112  of the upper press member, each gas inlet being located in about the center of a quadrant of the lower surface  112 . In another example, the upper press member can have more than four, more than 6, or more than 8 gas inlets  154 . Preferably, the upper press member  110  has at least one gas inlet  154  located near the center of its lower surface  112  and at least one gas inlet  154  located in each quadrant of its lower surface  112  to facilitate even distribution of compressed gas to wetted biomass  400  within the biomass receptacle  105 . 
     The gas injection system  150  can receive dry, clean compressed gas from a compressed gas supply system  180 , as shown in  FIG. 15 . In some instances, the gas injection system  150  can deliver compressed gas, such as nitrogen, argon, or carbon dioxide, to the solvent recovery apparatus  100 . In other instances, the gas injection system  150  can deliver clean, dry compressed air to the apparatus  100 . To avoid contaminating the solvent  300  with water or particles, it is desirable to remove water vapor and unwanted particles from the compressed air prior to delivering the air to the gas injection system  150 . The compressed gas delivery system  180  can be configured to remove water vapor and unwanted particles from the compressed gas before it reaches the gas injection system  150 . 
     Since the essential oils that are extracted from the plant matter may be consumed by humans or used in personal care products, it is desirable to comply with food safety regulations and to use food-safe components in the solvent recovery process. Accordingly, the compressed gas that is used to purge solvent from the biomass during the gas injection process should be clean and free of unwanted particles. 
     A compressed gas supply system  180 , as shown in  FIG. 15 , can supply clean, dry compressed gas to the gas injection system  150 . The compressed gas supply system  180  can include an oil-less compressor  900  fluidly connected to a compressed gas storage tank  905  by a gas supply line  901 . Using an oil-less compressor is desirable to avoid introducing lubricating oil mist into the compressed air during the compression stage. The storage tank  905  can serve as a reservoir of compressed gas. As compressed gas is drawn from the storage tank  905  for use by the gas injection system  150 , the compressor  900  can cycle on to replenish the storage tank with compressed gas as needed to maintain a desired gas pressure within the tank. In one example, the compressor can be operated to maintain the storage tank at a pressure of about 40-80, 60-100, 80-120, or preferably about 60-80 psi. The compressed gas supply system  180  can include a gas supply line  902  extending between the gas storage tank  905  and a gas filtration system  910 . In one example, the gas supply line  902  can be at least 50 feet in length to permit compressed air, which may be at an elevated temperature due to the compression process, to cool prior to reaching the gas filtration system  910 . By increasing the length of the gas supply line  902 , the residence time of the compressed gas traveling through the supply line is increased, which allows the gas sufficient time to cool, which can allow water vapor in the gas to condense so it can be more easily removed. A filter in the gas filtration system  910  can remove condensed water from the compressed gas. The gas filtration system can include at least one particulate filter to allow for unwanted particles to be removed from the compressed gas before it is delivered to the gas injection system  150  of the apparatus  100 . Preferably, the gas filtration system can include two or more particulate filters connected in series to allow for progressively smaller unwanted particles to be removed from the compressed gas before it is delivered to the gas injection system  150  of the apparatus  100 . In one example, the filtration system can be a four-stage air drying system, such as a model number U4060M-NO4DG-MEP Four Stage Air Drying System from PneumaticPlus including a 10 micron particulate filter/regulator, 0.3 micron oil mist removing filter, a 0.01 micron coalescing filter, and a drain to permit draining of collected water. A gas supply line  903  can fluidly connect the gas filtration system  910  to the gas injection system  150  of the apparatus  100 , as shown in  FIG. 15 . 
     The compressed gas delivery system  180  can include one or more flow control devices (e.g.  904 ,  905 ), such as valves or regulators, to control flow of pressurized gas through the compressed gas supply system  180 . A first flow control device  904  can be located between the storage tank  905  and the gas filtration system  910 . A second flow control device  910  can be located between the gas filtration system  910  and the gas injection system  150 . 
     In one example, the compressed gas delivery system  180  can include at least one pressure regulator (e.g.  904 ,  905 ) located between the storage tank  905  and the gas injection system  150 . The pressure regulator can allow the system to deliver compressed gas at any pressure at or below the pressure of gas in the storage tank  904 . This can allow an operator of the gas injection system  150  to adjust the pressure based on certain factors, such as type of plant matter, level of homogenization of the plant material, and desired cycle time. 
     The upper press member  110  can include a seal  120  proximate the lower surface  112  of the upper press member, as shown in  FIG. 4 . The seal  120  can extend around a perimeter of the upper press member  110 . To keep the seal  120  in place, it can be seated in an O-ring groove that extends around the perimeter of the upper press member  110 . The seal  120  can allow the upper press member  110  to seal against a surface (e.g. a rim surface  109 ) of the biomass receptacle  105 , as shown in  FIG. 10 , and form a gas-tight seal. The seal  120  can be a rubber (e.g. butyl rubber) O-ring, gasket, or any other suitable sealing member that is compatible with the solvent. The seal  120  can prevent pressurized gas that is delivered to the inner volume  165  of the biomass receptacle  105  by the gas injection system  150  from escaping from the inner volume at the junction between the upper press member  110  and the biomass receptacle. Instead, when the apparatus  100  is in the closed position, as shown in  FIG. 14 , the seal  120  ensures that compressed gas delivered to the inner volume  165  of the biomass receptacle  105  can only leave the inner volume of the biomass receptacle through the holes  106  in the biomass receptacle. The compressed gas flows downward through the holes  106  in the biomass receptacle  105  and drives the solvent to the drainage opening  140  where it can be recovered. In an alternate embodiment, the seal  120  can be installed on the biomass receptacle  105 , and the upper press member  110  can engage the seal when the apparatus  100  is in a closed position, thereby forming an effective seal between the upper press member  110  and the biomass receptacle  105 . 
     The apparatus  100  can include a means for compressing the mixture of biomass  400  and solvent  300  while the mixture is positioned in the biomass receptacle  105 . The means for compressing the mixture of biomass and solvent can be a pneumatic actuator, a hydraulic actuator, a manual actuator, or any other suitable actuator or combination or actuators. 
     Since solvents (e.g. ethanol, hexane, acetone) can be flammable, to enhance safety of the solvent recovery apparatus  100 , it can be desirable for the apparatus to not contain electrical components that could spark and potentially ignite the solvent. Accordingly, dynamic components of the apparatus, such as the actuator  125 , can be pneumatic, hydraulic, or manual to reduce the likelihood of a fire or explosion. 
     The actuator  125  shown in  FIG. 1  is a pneumatic actuator that moves the lower press member  115  vertically when compressed air is delivered to the actuator. In one example, the actuator  125  can be an 8-ton pneumatic jack. In other examples, the actuator can be a 5-10, 8-12, 10-15, 14-20 ton or more than 5-ton pneumatic or hydraulic actuator. The actuator  125  can include a cylinder  128  and a piston  126  that is movable relative to the cylinder. 
     The actuator  125  can be configured to transition the solvent recovery apparatus  100  between an open position (see  FIG. 9 ) and a closed position (see  FIG. 10 ). When in the open position, the length of an exposed portion of the ram  126  can be equal to L 1 , as shown in  FIG. 9 . When the apparatus is in the open position, the biomass receptacle  105  can be positioned a suitable distance below the upper press member  110  to allow a flexible receptacle  160  of biomass  400  to be placed into the biomass receptacle without interference from the upper press member. When in the closed position, the length of an exposed portion of the ram  126  can be equal to L 2 , as shown in  FIG. 10 . When transitioning the apparatus  100  between the open position and the closed position, the exposed portion of the ram can transition from L 1  and L 2 . 
     In addition to being actuated with compressed air, the actuator  125  in  FIG. 1  can also be actuated manually by inserting a lever into a lever receiver  127  near the base of the actuator and pumping the lever manually. In one example, an operator can place a container  160  of biomass  400  in the biomass receptacle as shown in  FIG. 13  and then use compressed air to transition the solvent recovery apparatus  100  from an open position shown in  FIG. 9  to a closed position shown in  FIG. 10 . Once the apparatus is in the closed position and the biomass receptacle  105  is seated against the seal  120  of the upper press member  110 , the operator can then pump the lever manually to increase L 2  and thereby increase the compressive force applied to the biomass material  400 . Increasing the compressive force can encourage a mixture of solvent  300 , essential oils, waxes, fats, and other lipids (collectively, “solvent mixture”) to flow out of the biomass and then flow downward through the apparatus to the drainage opening  140  where it can be recovered. Increasing the compressive force can also ensure the seal  120  is properly seated against the biomass receptacle  105  prior to operating the pressurized gas injection system  150 . 
     The solvent recovery apparatus  100  can include a lower press member  115 . The lower press member (drain basket)  115  can collect solvent that flows through the holes in the biomass receptacle (perforated basket)  105  and funnel the solvent to a drainage opening  140  that is fluidly connected to the vessel (dunk tank)  200 , as shown in  FIG. 14 . 
     The lower press member  115  can be attached to the actuator  125 , as shown in  FIGS. 1 and 9 . The lower press member (drain basket)  115  can have an inner surface (drainage surface)  116  and an outer surface  117 . The lower press member can have a support surface configured to receive and support the biomass receptacle. As shown in  FIG. 9 , the support surface  119  that receives and supports the biomass receptacle  105  can be an upper portion of the drainage surface  116  of the lower press member  110 . As shown in  FIG. 9 , a seal  118  can provide a gas-tight seal between the lower press member  115  and the biomass receptacle  105 . In some examples, the biomass receptacle  105  can be fastened to the lower press member  115 , as shown in  FIGS. 1-4 , to prevent unwanted movement of components during the pressing process. 
     In  FIG. 8 , the biomass receptacle  105  is removed from the solvent recovery apparatus  100  to reveal the inner surface  116  of the lower press member  115 . The lower press member  115  can include a drainage opening  140  that is located at a low point in the inner surface  116  to utilize gravity when collecting the solvent. The lower press member  115  can have a curved (convex) inner surface  115 . In one example, the drainage surface  116  of the upper press member  110  can be hemispherical. Curvature of the drainage surface  116  can encourage the solvent to flow from the holes  106  of the biomass receptacle to the drainage opening  140 . 
     The lower press member  115  can be made of a rigid material capable of withstanding compression without deflecting significantly. In some examples, the lower press member  115  can be made of food-safe material (e.g. stainless steel) and have a thickness of at least 0.25, 0.375, or 0.5 in. 
       FIGS. 11-14  show an example process for recovering solvent from biomass  400 .  FIG. 11  shows a step of soaking biomass  400  in solvent to extract essential oils from the biomass.  FIG. 12  shows a step of transferring the biomass from the vessel containing solvent (i.e. dunk tank) to a solvent recovery apparatus  100  using a transfer plate  500 .  FIG. 13  shows a step of placing the biomass, which is wetted or saturated with solvent, in the biomass receptacle of the solvent recovery apparatus  100 .  FIG. 14  shows the steps of applying compressive force to the biomass by transitioning the apparatus  100  from an open position to a closed position and applying gas pressure via a gas injection system  150 . 
     Prior to the step shown in  FIG. 11 , the vessel must be filled with solvent  300 . During the filling process, solvent can be transferred to the vessel via a solvent supply line  265  fluidly connected to an inlet fitting  270 . The inlet fitting  270  and be connected to an inlet port  260  of the vessel  200 . A pump can drive flow from a supply tank to the solvent vessel  200 . To avoid risk of fire, the pump can operate on compressed air and have no electrical components. In one example, the pump can be a SimpleSpirits air diaphragm distillery pump from VersaMatic. The pump can be compatible with 190-proof ethanol and be ATEX-rated. 
       FIG. 11  shows a vessel  200  containing solvent  300  located beside an apparatus  100  for recovering solvent. A flexible receptacle  160  containing biomass  400  is shown submerged in solvent within the vessel  200 . During the step shown in  FIG. 11 , the biomass  400  is permitted to soak in the solvent  300  for a predetermined amount of time to allow the solvent to extract desired essential oils from the biomass. The essential oils are able to permeate the material(s) of the flexible receptacle  160  and thereby mix with the solvent in the vessel. The solvent  300  can be any suitable solvent capable of safely extracting desirable materials, such as essential oils, from the biomass. In a preferred example, the solvent can be ethanol (i.e. ethyl alcohol). 
     The desired amount of time that the biomass  400  is submerged in the solvent  300  depends on, in part, the level of homogenization of the plant matter and the temperature of the solvent. Typically, the colder the solvent, the longer the biomass will need to soak to extract essential oils from the biomass. For example, if the solvent is room temperature, the biomass may only need to soak for about 5 mins, whereas if the solvent is −25 degrees Celsius, the biomass may need to soak for 15 minutes or more. The desired amount of time that the biomass  400  is submerged in the solvent  300  may also depend on desired extraction efficiency and process constraints, such as allowable cycle times. 
     The flexible receptacle  160  can be a pliable container made of fabric or any other suitable material or combination of materials. In a preferred embodiment, the flexible receptacle  160  can include an interior bag  161  positioned within an exterior bag  162 . The interior bag  161  can be made of a breathable, tear-resistant, odor free fabric. The interior bag can be made of food-safe materials, such as woven cotton. The interior bag can be configured to receive the biomass and can be relatively supple and function as a first biomass filter that restricts large biomass particles from exiting the interior bag. In preferred examples, the interior bag is made of a light cotton fabric or light blended cotton and polyester fabric, similar to the material used in wild game bags manufactured by Alaska Game Bags, Inc. 
     The exterior bag  162  can be made of food-safe materials (e.g. cotton fabric). The exterior bag can be made of a less supple material than the interior bag. In a preferred example, the exterior bag  162  can be made of a durable plain-woven fabric, such as canvas, which can be made of cotton. In other examples, the exterior bag can be canvas made of linen, or hemp. In still other examples, the exterior bag can be made of a durable fabric with a twill weave, such as denim. The exterior bag can function as a second biomass filter that restricts relatively smaller biomass particles (i.e. biomass particles that passed through the interior bag) from passing through the exterior bag and ending up in the vessel  200 . In one example, the exterior bag can be made of a material that filters particles larger than about 200 microns. 
     The material of the exterior bag  162  can be stiffer than the material of the interior bag  161 . In one example, the material of the exterior bag can be sufficiently stiff to avoid being drawn into the plurality of holes  106  in the biomass receptacle  105  while pressing the flexible receptacle  160  in the apparatus  100  and applying pressurized gas to the flexible receptacle  160 , as shown in  FIG. 14 . Preventing the material of the exterior bag  162  from being drawn into the plurality of the holes can be desirable, since it can prevent the exterior bag from being damaged (e.g. torn), which could result in biomass escaping the bag and plugging the holes  106  in the biomass receptacle or drainage opening  140  or contaminating the solvent mixture that flows back to the vessel  200  in the step shown in  FIG. 14 . 
     The vessel  200  can include a temperature control system to enable chilling of the solvent. In one example, the vessel  200  can be a stainless steel jacketed vessel fluidly connected to a chiller unit that supplies chilled liquid, such as a water-glycol mixture, to isolated passageways in the wall(s) of the vessel. The chilled liquid can be isolated from the solvent within the vessel and, therefore, does not mix with the solvent. While the vessel does not need to be cooled to function, providing cooling is preferred to produce high quality essential oils, which can be more desirable to consumers and more valuable. 
     In a quick wash ethanol process, the solvent can be capable of removing both essential oils and waxes from the plant matter. Typically, essential oils are desirable and valuable, and waxes are undesirable. It is therefore desirable to operate the extraction process in a way that increases the amount of essential oils recovered and decreases the amount of waxes recovered. Typically, the colder the solvent is, the less wax will be extracted. However, if the solvent is too cold, the extraction efficiency decreases and the time required to extract essential oils will increase, leading to longer processing times, which is undesirable from a commercial processing standpoint. In a preferred example, the solvent  300  in the vessel  200  can be maintained at about −20 to −30 degrees Celsius. This temperature range produces a high yield of desirable essential oils and a low yield of undesirable waxes. 
     The vessel  200  (dunk tank) can include a lid  210 . The lid  210  can be configured to open via a hinge or other suitable mechanism or can be entirely removable. As shown in  FIG. 11 , the vessel  200  can include an inlet port  260  to allow for filling of the vessel. In one example, the inlet port  260  can be located in a removable lid  210 . The inlet port  260  can include an inlet fitting  270  (e.g a stainless steel tri-clamp fitting) that is configured to fluidly connect the vessel to a solvent supply line  265 . The solvent supply line  265  can be made of food-grade materials (e.g. silicone tubing) to avoid contamination of the solvent and to allow the extracted essential oils to comply with food and drug regulations and be used in edible products and personal care products. 
     After the biomass  400  has been submerged in solvent  300  for a sufficient duration (e.g. 3-5 minutes), the flexible receptacle  160  can be transferred from the vessel  200  (i.e. dunk tank) to the solvent recovery apparatus  100 .  FIG. 12  shows a step of transferring the flexible receptacle  160  from the vessel  200  to the apparatus  100 . A transfer plate  500  can extend from the vessel to the apparatus. In one example, the transfer plate  500  can be a stainless steel plate with a first wall  501  extending upward from a first edge of the plate and a second wall  501  extending upward from a second edge of the plate, as shown in  FIG. 12 . The transfer plate  500  can include a first lip  502  configured to rest against an inner wall of the vessel  200  and ensure that solvent flowing down the transfer plate is returned to the vessel. The transfer plate  500  can include a second lip  503  configured to rest against the inner surface  107  of the biomass receptacle  105  to keep the transfer plate in place during transfer of the flexible receptacle  160 . 
     A first purpose of the transfer plate  500  is to prevent loss of solvent leaking from the bag  160  by catching the solvent and conveying the solvent back into the vessel. The transfer plate  500  can be arranged at an incline, as shown in  FIG. 12 , to encourage the solvent to flow back into the vessel due to gravity. The walls of the transfer plate  500  can prevent solvent from flowing off the edges of the plate before it reaches the vessel. 
     A second purpose of the transfer plate  500  is to reduce a physical strain on an operator who is transferring the bag  160  from the vessel  200  to the press apparatus  100 . The transfer plate  50  can support the weight of the bag and its contents during the transfer process, so the operator doesn&#39;t need to lift the full weight of the bag and its contents during the transfer process. Instead, since the bag is saturated with solvent, an operator can easily slide the bag along the transfer plate with relatively little physical effort from the vessel  200  to the biomass receptacle  105 . 
       FIG. 13  shows a step of placing the container  160  of biomass  400 , which is wetted or saturated with solvent  300 , in the biomass receptacle  105  of the solvent recovery apparatus  100 . In  FIG. 13 , the apparatus  100  is in an open position, which provides a sufficient distance between the upper press member  110  and the biomass receptacle  105  to allow an operator to place the flexible receptacle  160  of biomass  400  into the biomass receptacle without interference with the upper press member  110 . The flexible receptacle  160  can be positioned in any suitable way within the biomass receptacle. Preferably, the flexible receptacle  160  is placed in the biomass receptacle  105  with its largest surface resting against the inner surface  107  of the biomass receptacle and covering as many of the holes  106  as possible. Covering the holes is desirable, since it causes more of the compressed gas to flow through the bag and the biomass (rather than short-circuiting around the bag) thereby entraining solvent and improving solvent recovery yield. 
       FIG. 14  shows a step of applying compressive force to the biomass in a flexible receptacle  160  by transitioning the apparatus  100  from an open position to a closed position and then applying gas pressure via the gas injection system  150 . Compressing the flexible receptacle  160  of biomass  400  can effectively squeeze solvent from the biomass. The solvent can then flow through the holes  106  in the biomass receptacle and downward to the drainage opening  140 . The drainage opening  140  can be connected to a solvent recovery line  230  that transports the solvent back to the vessel  200 . As shown in  FIGS. 10 and 14 , the convex upper press member  110  can nest within the concave biomass receptacle  105 , thereby allowing for uniform compression of the wetted biomass  400  in the flexible receptacle  160  while also promoting drainage, by gravitational force, of recovered solvent to the drainage opening  140 . Likewise, the biomass receptacle  105  can nest within the lower press member  115  to provide a compact yet durable apparatus that can withstand significant compressive forces and efficiently return solvent to the drainage opening  140 . 
     To increase the amount of solvent recovered from the wetted biomass  400 , pressurized gas can be injected proximate a top surface of the flexible receptacle, as shown in  FIG. 14 . Gas at a pressure of 10-30, 20-40, 30-50, 40-60, 50-70, 60-80, 70-90, or more than 75 psi can be injected into the inner volume  165  of the biomass receptacle. Preferably, air at a pressure of about 15-25 psi is injected proximate a top surface of the flexible receptacle  160  for a first period of time until the flow of solvent through the drainage opening  140  slows or stops, and then air at a pressure of about 60-80 psi is injected proximate a top surface of the flexible receptacle  160  for a second period of time until the flow of solvent through the drainage opening  140  slows or stops. In most instances, the second stage of air injection will completely or nearly completely dry the biomass in the bag  160  and will replace the air in the head space of the  240  of the vessel with clean, dry air, which is desirable to prolong the useful life of the solvent by minimizing exposure to water vapor in non-dry air. 
     The pressurized gas can flow through the bag  160  and biomass material  400  thereby entraining solvent and transporting the solvent to the drainage opening  140  of the solvent recovery apparatus. More specifically, as shown in  FIG. 14 , the pressurized gas can flow through an upper surface of the flexible receptacle  160  that is in contact with the lower surface  112  of the upper press member  110 , then flow through the wetted biomass  400 , then flow through a lower surface of the flexible receptacle that is in contact with the inner surface  107  of the biomass receptacle, then flow through the holes  106  in the biomass receptacle, and then flow to the drainage opening  140 . The bag(s) of the flexible receptacle  160  can serve as biomass filters and prevent biomass particles (e.g. particles larger than about 200 microns) from passing through the flexible receptacle and entering the stream of solvent returning to the vessel  200 . 
     As shown in  FIGS. 2 and 14 , the drainage opening  140  can include a drainage valve  141  to allow an operator to control the flow of solvent back to the vessel  200  via the solvent recovery line  230 . 
     As shown in  FIG. 14 , the vessel  200  can include a bleed valve  275  to allow for relief of gas pressure from an upper portion of the vessel. The bleed valve  275  can allow the vessel lid  210  to remain closed while applying gas pressure to the biomass  400  and forcing a flow of pressurized gas and solvent from the drainage opening  140  of the apparatus back to the vessel  200 . The bleed valve  275  can allow purging of gas from the head space  240  of the vessel, which can improve the flow of solvent from the apparatus  100  to the vessel during operation of the gas injection system  150 . This bleed valve  275  allows an operator to keep the lid  210  of the vessel closed while pressing the biomass and passing pressurized gas through the biomass. By keeping the lid  210  on the vessel, it prevents non-dry air from entering the head space  240  of the vessel. By preventing the solvent from absorbing water from the atmosphere, the solvent stays at a higher proof for a longer period of time and, therefore, has a longer useful process life. If non-dry enters the head space  240  of the vessel  200 , it can be purged from the head space by flowing compressed air through the gas injection system (which receives clean, dry air from the compressed gas supply system  180 ) and opening the bleed valve  275  of the vessel  200  to allow gas to escape from the head space  240  of the vessel. 
     After the solvent is recovered from the biomass  400  in the step shown in  FIG. 14 , the solvent in the vessel  200  can then be transported to a conical storage vessel  1000 , as shown in  FIG. 16 , where waxes, fats, and other lipids are removed from the solvent. 
     As shown in  FIG. 14 , the solvent vessel  200  can include an outlet port  220  near a base of the vessel. The outlet port can include an outlet fitting  221  (e.g stainless steel tri-clamp fitting) that is fluidly connected to a solvent discharge line  235 . The outlet fitting  221  and solvent discharge line  235  can be made of food-grade material(s) to avoid contamination of the solvent. The vessel  200  can include an outlet valve  225  proximate the outlet port  220 . 
     After operating the solvent recovery apparatus  100 , the solvent mixture that is recovered from the bag  160  flows back into the vessel  200  via the solvent recovery line  230 . The outlet valve of the vessel can then allow the mixture of solvent, essential oils, and waxes in the vessel to be easily transferred via the discharge line  235  to a conical storage vessel  1000  for a winterization process. 
     To minimize the risk of fire, a non-electric pump, such as a SimpleSpirits air diaphragm distillery pump from VersaMatic, can be used to pump the mixture to the conical storage vessel  1005 . The pump can be compatible with 190-proof ethanol and be ATEX-rated. The conical storage vessel can be appropriately sized to receive the volume of solvent being transferred from the solvent vessel  200 . The conical storage vessel can be maintained at a temperature of about −10 to −20 Celsius. In one example, the conical storage vessel can be housed in a walk-in freezer. 
     The purpose of the winterization process is to remove waxes, fats, and other lipids from the mixture of ethanol and essential oils. In some applications, such as when creating distillate, it is desirable to remove waxes, fats, and other lipids to improve the clarity of the distillate. 
     After the ethanol is pumped into the conical storage vessel  1000 , it begins to cool. Waxes, fats, and other lipids precipitate out of solution and fall to the bottom of the conical storage vessel. During precipitation, the wax does not stick to the walls of the conical storage vessel, because its walls are steep. Instead, the waxes migrate into the center of the cone and collect in a spool that extends from the bottom of the conical storage vessel  1000 . The spool  1001  can be a long slender member suitable for capturing a volume of waxes, fats, and other lipids that precipitate out of solution. In one example, the spool is a stainless steel tube that attaches to the conical with a tri-clamp fitting and is capped on an opposing end. A valve between the conical storage vessel and the spool can be closed prior to removal of the spool to avoid any loss of solvent. The spool allows for easy removal of precipitate without agitating the solution and causing the waxes to be redissolved. 
     Once the spool  1001  is removed from the conical storage vessel  1000 , the wax can be filtered out using a Buchner funnel. Any amount of ethanol remaining in the spool can be recovered and sent to the ethanol recovery system  1010  where the ethanol is separated from the essential oils. 
     After the spool has been removed from the conical storage vessel, the mixture in the conical storage vessel can be transferred through a multi-stage filtrations system  1005  and then to an ethanol recovery system  1010 , as shown in  FIG. 16 . In one example, the ethanol recovery system can be a rotary evaporator. The ethanol recovery system can allow the mixture to be separated into solvent and distilled essential oils. The solvent can then be reused in a subsequent extraction process and the distilled essential oils can be used in a wide variety of products. 
     In one example, a method for recovering solvent  300  from biomass  400  can include providing a flexible receptacle  160  containing biomass and liquid solvent, placing the flexible receptacle containing biomass and liquid solvent into a biomass receptacle  105  where the biomass receptacle has a plurality of openings  106 , pressing the flexible receptacle against the biomass receptacle and causing at least a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings  106  in the biomass receptacle  105 , and flowing gas through the flexible receptacle containing biomass and liquid solvent to force at least a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings in the biomass receptacle where it can be recovered, as shown in  FIG. 14 . Flowing gas through the flexible receptacle  160  can include delivering gas at a pressure of 5-100, 10-50, 15-25, or 20 psi proximate a top surface of the flexible receptacle  160 . Flowing gas through the flexible receptacle  160  can include delivering gas at a first pressure for a first predetermined duration and delivering gas at a second pressure for a second predetermined duration. The first pressure can be 10-25, 10-30, or 25-40 psi, and the second pressure can be 40-75, 50-100, or 75-125 psi. The first predetermined duration can be 0.5-3, 2-5, or 5-15 minutes, and the second predetermined duration can be 0.5-3, 2-5, or 5-15 minutes. The gas can be selected from a group consisting of nitrogen, argon, air, and carbon dioxide. Pressing the flexible receptacle  160  against the biomass receptacle  105  can include applying a pressure of 10-30, 20-50, 30-50, 40-60, 50-70, 60-80, 70-90, or 80-100 psi to the flexible receptacle. Providing the flexible receptacle can include soaking the flexible receptacle in a vessel of liquid solvent (see  FIG. 11 ) for a predetermined duration and transferring the flexible receptacle from the vessel of liquid solvent to the biomass receptacle using a transfer plate (see  FIG. 12 ). The transfer plate  500  can extend on a decline from the biomass receptacle  105  of a solvent recovery apparatus  100  to the vessel  200  of solvent, allowing liquid solvent that drains from the flexible receptacle during the transfer process to flow on the transfer plate back into the vessel of solvent. Providing the flexible receptacle  160  containing biomass and liquid solvent can include filling an interior bag  161  with biomass  400  and placing the interior bag within an exterior bag, where the exterior bag is made of a durable woven fabric. Pressing the flexible receptacle against the biomass receptacle can occurs prior to, after, or while flowing gas through the flexible receptacle. Preferably, pressing the flexible receptacle  160  against the biomass receptacle can occur prior to and while gas is flowed through the flexible receptacle, as shown in  FIG. 14 . In this example, the biomass  400  remains under compression while compressed gas flows through the biomass, which can increase the amount of solvent that is recovered from the flexible receptacle. 
     In another example, a method for recovering solvent  300  from biomass  400  can include providing a flexible receptacle  160  containing biomass and liquid solvent, placing the flexible receptacle of biomass and liquid solvent into a concave biomass receptacle  105  where the concave biomass receptacle has a plurality of openings along a bottom surface of the concave biomass receptacle (see  FIG. 13 ), pressing a convex press member against the flexible receptacle containing biomass and liquid solvent and thereby compressing the biomass and causing a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings in the concave biomass receptacle (see  FIG. 14 ), flowing pressurized gas through the flexible receptacle of biomass and liquid solvent thereby causing a portion of the liquid solvent to exit the flexible receptacle and flow through the plurality of openings in the concave biomass receptacle, and collecting the liquid solvent that flows through the plurality of openings in the concave biomass receptacle. Flowing pressurized gas through the flexible receptacle of biomass  105  and liquid solvent can include flowing gas at a pressure of 5-15, 10-25, 20-40, 30-60, 50-70, 60-80, 70-90, 80-100 psi through the flexible receptacle containing biomass and liquid solvent. Pressing the convex press member  110  against the flexible receptacle  160  of biomass and liquid solvent can include pressing the convex member against the flexible receptacle of biomass and liquid solvent by applying a pressure of 10-30, 20-50, 30-50, 40-60, 50-70, 60-80, 70-90, or 80-100 psi. Providing the flexible receptacle containing biomass and liquid solvent can include providing an interior bag  161  containing the biomass  400  and liquid solvent  300  where the interior cotton bag is positioned within an exterior bag made of canvas, as shown in  FIG. 14 . Pressing the convex press member  110  against the flexible receptacle  160  of biomass and liquid solvent can occur prior to, while, or after flowing pressurized gas through the flexible receptacle of biomass and liquid solvent. 
     In another example, a method for recovering liquid solvent  300  from biomass  400  can include providing a biomass receptacle  105  containing a mixture of biomass and liquid solvent, exerting pressure on the mixture of biomass and liquid solvent while the mixture is positioned in the biomass receptacle, flowing pressurized gas through the mixture of biomass and liquid solvent while the mixture is positioned in the biomass receptacle, and collecting the liquid solvent that exits the biomass receptacle. 
     In one example, an apparatus  100  for recovering liquid solvent  300  from wetted or saturated biomass  400  can include a biomass receptacle  105  having an inner surface  107 , an outer surface  108 , and a plurality of holes  106  extending through the biomass receptacle from the inner surface to the outer surface where the inner surface of the biomass receptacle defines an inner volume. The apparatus can include a lower press member  115  having a support surface  119  configured to receive and support the biomass receptacle  105 , an upper press member  110  having a lower surface  112  configured to seal against a rim surface  109  of the biomass receptacle, and an actuator  125  configured to transition the apparatus from an open position to a closed position, where the inner volume  165  of the biomass receptacle is accessible when the apparatus is in the open position, and where the lower surface  112  of the upper press member  110  seals against the rim surface of the biomass receptacle  105  when the apparatus is in the closed position. The apparatus can include a gas injection system configured to deliver pressurized gas to gas inlets in the lower surface of the upper press member. The gas injection system can be configured to deliver gas at a pressure of 15-80 psi to the gas inlets in the lower surface of the upper press member. The actuator can be configured to apply a compressive force of 10-50, 25-75, 50-100, 75-150, or 100-200 psi between the upper press member and the biomass receptacle when the apparatus is in the closed position. A portion of the upper press member (plunger)  110  can occupy a portion of the inner volume  165  of the biomass receptacle  105  when the apparatus  100  is in the closed position, thereby decreasing available space within the inner volume for a mixture of biomass  400  and solvent and allowing the upper press to compress the biomass and squeeze solvent  300  from the biomass. The lower surface  112  of the upper press member  110  can be a convex surface that occupies a portion of the inner volume of the biomass receptacle when the apparatus is in the closed position, thereby decreasing available space within the inner volume for a mixture of biomass and solvent and allowing the upper press to compress the biomass and squeeze solvent from the biomass. The lower press member can include a drainage surface  116  and a drainage opening  140  fluidly connected to the drainage surface. The apparatus can include a gap  145  between the outer surface  108  of the biomass receptacle  105  and the drainage surface  116  of the lower press member  115  where the gap is configured to permit drainage of liquid solvent from the holes  106  in the biomass receptacle  105  to the drainage opening  140  in the lower press member when the apparatus is in the closed position. At least one of the plurality of holes in the biomass receptacle  105  can have a diameter of about 0.125-0.375 in. The gas injection system  150  can include a gas manifold  151  fluidly connected to one or more gas passageways  152 , where the one or more gas passageways are fluidly connected to the gas inlets  154  in the upper press member  110 . Each gas passageway  151  can be configured to deliver pressurized gas into the inner volume  165  of the biomass receptacle  105  when the apparatus is in the closed positioned and pressurized gas is supplied to the manifold. The apparatus can include a seal  120  between the lower surface  112  of the upper press member  110  and the rim surface  109  of the biomass receptacle  105 . The actuator  125  can be a pneumatic actuator or a hydraulic actuator. 
     In another example, an apparatus  100  for recovering liquid solvent from biomass can include a press having an upper press member  110 , a lower press member  115 , and an actuator  125 , where the actuator is configured to reduce the distance between the lower press member and the upper press member. The apparatus  100  can include a biomass receptacle  105  positioned between the lower press member  115  and the upper press member  110 , where the lower press member and upper press member together are configured to exert a compressive force on the biomass receptacle  105  when the apparatus is in a closed position. The apparatus can include a gas injection system  150  configured to deliver pressurized gas to an inner volume  165  of the biomass receptacle  105  when the apparatus is in the closed position. The apparatus can include a drainage opening  140  configured to allow liquid solvent to flow from the biomass receptacle  105  when the apparatus is in the closed position and a compressive force is exerted on a mixture of biomass and solvent present in the biomass receptacle. The actuator  125  can be configured to reduce the distance between the lower press member  115  and the upper press member  110  by advancing the lower press member toward the upper press member. The actuator  125  can be configured to reduce the distance between the lower press member and the upper press member by advancing the upper press member toward the lower press member. The biomass receptacle  105  can have an inner surface  107 , an outer surface  108 , and a plurality of openings  106  extending from the inner surface to the outer surface. The inner surface  107  of the biomass receptacle  105  can be hemispherical. The upper press member  110  can have a convex hemispherical surface  112  that is configured to exert a compressive force on a mixture of biomass  400  and solvent  300  when the mixture is located in the concave hemispherical biomass receptacle. The apparatus  100  can include a flexible receptacle  160  having an interior bag and an exterior bag, where the interior bag is configured to insert within the exterior bag, and where the exterior bag comprises a durable fabric. 
     In another example, an apparatus  100  for recovering liquid solvent  300  from biomass  400  can include a biomass receptacle  105  configured to receive a mixture of biomass and liquid solvent, a means for exerting a compressive force on the mixture of biomass and liquid solvent while the mixture is positioned in the biomass receptacle (see, e.g.,  FIG. 14 ), a means for flowing pressurized gas through the mixture while the mixture is positioned in the biomass receptacle (see, e.g.,  FIG. 14 ), and a means for collecting the liquid solvent that exits the biomass receptacle (see, e.g.,  FIG. 14 ). 
     The elements and method steps described herein can be used in any combination whether explicitly described or not. All combinations of method steps as described herein can be performed in any order, unless otherwise specified or clearly implied to the contrary by the context in which the referenced combination is made. 
     As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. 
     Numerical ranges as used herein are intended to include every number and subset of numbers contained within that range, whether specifically disclosed or not. Further, these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from 1 to 10 should be construed as supporting a range of from 2 to 8, from 3 to 7, from 5 to 6, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth. 
     All patents, patent publications, and peer-reviewed publications (i.e., “references”) cited herein are expressly incorporated by reference to the same extent as if each individual reference were specifically and individually indicated as being incorporated by reference. In case of conflict between the present disclosure and the incorporated references, the present disclosure controls. 
     The methods and compositions of the present invention can comprise, consist of, or consist essentially of the essential elements and limitations described herein, as well as any additional or optional steps, components, or limitations described herein or otherwise useful in the art. 
     It is understood that the invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the claims. 
     The foregoing description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the claims to the embodiments disclosed. Other modifications and variations may be possible in view of the above teachings. The embodiments were chosen and described to explain the principles of the invention and its practical application to enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.