Patent Publication Number: US-2021172680-A1

Title: Hemp biomass drying assembly

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 62/943,853, filed Dec. 5, 2019, the content of this application is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed to a drying assembly, and more particularly a drying assembly for hemp biomass. 
     Interest in growing industrial hemp for CBD production has grown, particularly since hemp was legalized in the 2018 Farm Bill. Drying the hemp biomass once it has been harvested is an important step in the process. Hanging plants upside down on wires in a drying space such as a barn is one way of drying the plant. Unfortunately, as the plants dry the branches droop resulting in reduced air flow to the center of the hemp plants. As a result, mold and mildew tend to grow in the center portion. The damage can be reduced by breaking the branches off and hanging the individual branches, but the process is labor intensive. Also, this process requires approximately three days to dry the hemp in a drying space of between 800 to 2500 square feet. 
     Another method of drying hemp plants is to spread the plants across the floor of a structure. Not only does this practice require a good amount of space, but individuals often step on the plant packing the plant material together. Also, the process requires one to turn the plants repeatedly with a shovel which is time and labor intensive. 
     A still further method of drying hemp biomass material is through the use of a stirring device that pivots about a center of drying floor. A rotor, having fingers, rotates to fluff the hemp plant to provide greater air flow. While useful, existing stirring devices are driven with a peripheral drive wheel that does not provide good traction because the hemp plant is slippery and also the device has a single mode of operation with fingers that move in only a single direction. 
     Hemp has an oily, glue like component contained in the flower which is where desired chemicals are derived from. Based upon these characteristics it is challenging to move through the biomass as it is sticky and abrasive, and because of its molecular structure and high moisture content, hemp tends to stick together. When compressed, air will not flow through the bio-mass which is why stirring is needed. Also, because of the fiberous makeup of the hemp biomass material a conventional auger used for moving particulate and granular material is ineffective in transporting hemp biomass material for drying purposes. 
     Also, hemp is typically harvested wet and has a 60 to 70 percent moisture content. To efficiently dry the hemp plant, not only are multiple modes of operation needed to spread, level, and stir the plant material, but the process needs to be adaptable to various geographic locations where ambient conditions (i.e., Iowa versus Oregon, Georgia or Florida) are different. Accordingly there exists a need in the art for a hemp biomass drying assembly that addresses these needs and deficiencies in the prior art. 
     An objective of the present invention is to provide a hemp biomass drying assembly that reduces the drying time of hemp. 
     Another objective of the present invention is to provide a hemp biomass drying assembly that is less labor intensive and more economical to use. 
     A still further objective of the present invention is to provide a hemp biomass drying assembly that has multiple modes of operation. 
     These and other objectives will be apparent to those having ordinary skill in the art based upon the following written description, drawings and claims. 
     SUMMARY OF THE INVENTION 
     A hemp biomass drying assembly disposed within a structure having a bottom wall and a side wall. The drying assembly includes a lift assembly disposed within the center of the structure. Connected to the lift assembly is a rotatable tine assembly and an auger assembly that extend radially from the center of the structure. The rotatable tine assembly and the auger assembly have multiple modes of operation that include a spreading mode, a leveling mode, a stirring mode, and an unloading mode. Attached to the auger assembly is an auger lift assembly that adjusts the angle of penetration between auger and the biomass and raises and lowers the auger assembly. 
     Disposed within the structure is a drying floor that separates the structure into a drying area above the drying floor and a drying air plenum between the drying floor and the bottom wall of the structure. Connected to the structure and in fluid communication with the drying air plenum is a drying system. The drying system includes at least one fan and at least one heater/burner that are connected to a control system that activates and controls the air flow and temperature of the drying system. 
     The auger assembly includes an auger and an adjustable backboard while the rotatable tine assembly includes a radial shaft, a mounting tube connected about the shaft, and a plurality of tines connected to the mounting tube. Connected to both the rotatable tine assembly and the auger assembly is a tractor drive assembly adapted to rotate both the rotatable tine assembly and the auger assembly about the center of the structure. 
     Connected to the lift assembly, the track drive assembly, the rotatable drive assembly, the auger assembly, and the auger lift assembly is a control system that activates and controls the operation for each of the multiple modes of operations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a drying system and a structure; 
         FIG. 2  is a side sectional view of a drying assembly; 
         FIG. 3  is a perspective view of a drying assembly; 
         FIG. 4  is a perspective view a drying assembly; 
         FIG. 5  is a side view of an auger lift system; 
         FIG. 6  is a side view of an auger assembly; and 
         FIG. 7  is a side view of an auger assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the Figures, a hemp biomass drying assembly  10  is used in relation to a structure or housing  12  having any size, shape or structure and in the example shown is circular. The housing  12  has a bottom wall  14  and a side wall  16 , with a roof or cover  18  being attached to a top edge of the side wall  16  which is optional. Disposed within the structure  12 , in parallel spaced relation to the bottom wall  14 , is an elevated perforated plenum drying floor  20  which separates the interior of the structure into a plant drying area  22  above the drying floor  20 , and a heated air plenum  24  between the drying floor  20  and the bottom wall  14 . The drying floor  20  preferably is made of steel and holds the biomass material while having small holes or perforations to permit air flow. 
     Connected to the side wall, and in communication with the heated air plenum  24 , is a drying system  26 . The drying system is of any type, structure or combination that provides drying air of any combination of temperatures and humidity to the air plenum and in the example shown, the drying system  26  includes a centrifugal or axial fan  27  that is used to supply the drying assembly  10  with drying air, and a heater/burner  28  used to raise the temperature of the drying air, that are connected to an air duct  30  that supplies heated air to the heated air plenum  24 . The heater/burner  28  are fueled by propane, natural gas, or an alternative fuel source. Multiple fans  27  and heaters/burners  28  can be added to the drying system  26  depending upon the drying capacity needed. The side wall  16  of the structure  12  has an unloading door  32  to the heated air plenum  24  positioned below the drying floor  20 , a biomass loading door  34  to the drying area  22  above the drying floor  20 , and an access door  36  to the drying area  22  above the drying floor  20 . 
     Disposed in the center of the structure  12  is a center mast tube lift assembly  38 . The lift assembly is of any shape, structure or size. In the example shown, the lift assembly  38  has a first tube  40  that is connected to the bottom wall  14  and extends vertically through the drying floor  20  and into the plant drying area  22 . Slidably and rotatably mounted about the first tube  40  is a second tube  42 . At a top end of the second tube  42 , electrical slip rings  44  are mounted about the second tube  42 , and a bracket  46  is connected to both the second tube  42  and the electrical slip rings  44 . The electrical slip ring assembly is connected to and provides power for various motors, sensors and/or other electrical devices within the drying assembly. A pair of cables  48  are connected to the bracket  46  and extend vertically to a first motor  50  that is positioned at a top end of the first tube  40 . The first motor  50  is of any type, but preferably is a jack screw lift. 
     Also attached to the second tube  42 , below the electrical slip rings  44  is an elongated horizontal support member  52  and below the horizontal support member  52  and attached to the second tube is a support bar bracket  54 . A pair of vertical support members  56  are connected to and extend between the horizontal support member  52  and the support bar bracket. Connected to the horizontal support member, at each end, are a pair of support rods  58  that extend downwardly and outwardly at an angle where they are connected to a tine support bar  60  and an auger support bar  62 . Adjacent inner ends of the tine support bar  60  and the auger support bar  62 , the vertical support members  56  of the support bar bracket  54  are connected. 
     A rotatable tine assembly  64  is connected to the tine support bar  60  by a vertical support member  68  at each end of the tine support bar  60 . The rotatable tine assembly  64  is of any size, shape and structure. In one example, the rotatable tine assembly  64  has a radial shaft  66  which extends from the center of the structure  12  to adjacent the side wall  16 . The radial shaft  66  is rotatably connected to the vertical support members  68  at each end. Connected to and around the radial shaft  66  is a mounting tube  70  to which a plurality of tines  72  are mounted. The mounting tube  70  has a plurality of holes  74  that receive the tines  72  and the holes are positioned along the mounting tube  70  in spaced relation in horizontal rows. Preferably, the holes are offset from the holes of an adjacent row. While tines  70  are shown, other devices such as paddles or the like may be used instead. 
     An auger assembly  76  is connected to the auger support bar  62  by a plurality of vertical support members  78  with at least one at each end of the auger support bar  62 . The auger assembly  76  includes an auger  80  having flighting  82  that is rotatably connected to the vertical support members  78  at each end. The vertical members  78  have a first piece  84  that is connected to the auger support bar  62  and a second piece  86  that is pivotally connected to the first piece  84 . The auger  80  is rotatably connected to the second piece  86  of the vertical support  78 . Connected to and extending between the second piece  86  of the vertical supports  78 , above the auger  80 , is a backboard support member  90 . A backboard  92  is attached to the backboard support member  90  and is positioned to cover a portion of the auger  80  along the length of the auger  80 . The backboard  92  provides a physical barrier that prevents the biomass from being transferred to the opposite side of the auger  80 . The backboard  92  also directs the conveyance of the biomass material to be parallel with the length of the auger  80 . Also connected to the second piece  86  of the vertical support member  78  on the inner end of the auger assembly  76  is an auger lifting assembly  93 . In one example the auger lifting assembly includes a piston  94  that extends vertically to a second motor  95 . The second motor  95  is attached to a vertical support member  56  of the lift assembly  38 . The auger lifting assembly provides the ability to raise or lower the auger assembly  76  to adjust the angle and depth of engagement that the auger  80  has with the biomass during the various modes of operation or to lift the auger assembly  76  out of engagement with the biomass. In manual operation the auger assembly  76  is raised or lowered with a toggle switch (not shown). 
     In one embodiment, the auger assembly  76  has a pair of backboards  92  connected to a pair of backboard lifting devices  93 A. Each backboard lift assembly  93 A includes a piston  94 A and an actuator  95 A such as a motor, pneumatic drive, or the like. The pistons  94 A are pivotally connected to the backboard  92  at on end and to a bracket  97  at the opposite end. The bracket  97  is connected to the second piece  86 . The actuators  95 A are connected to and controlled by the control system  110 . Depending which direction the auger assembly is travelling across the drying floor  20  the backboard lifting device  93 A on the front or forward side of the auger assembly  76  is activated so that the piston  94 A contracts raising the backboard  92  on the forward side while the backboard  92  on the reward or trailing side remains in place. 
     In yet another embodiment the backboard  92  is adjustable about the auger  80  based upon the direction of travel of the auger assembly  76 . To adjust the backboard  92  a rotational member  97  such as a sprocket with teeth is positioned above the backboard  92  and engages grooves  99  on the outer surface of the backboard  92 . The rotational member is mounted to the second piece  86  of the vertical support member  78 . Once activated by a control system  110  the rotatable member  97  rotates causing the backboard to rotate about the auger  80  to be positioned on the back side of the auger  80  and opposite the direction of travel of the auger assembly  76 . 
     A track assembly  96  is used to rotate the drying assembly  10  about the first tube  40  positioned in the center of the structure  12 . The track assembly includes a chain track  98  connected to an inner surface of the side wall  16  preferably in a plane above the tine support bar  60  and the auger support bar  62  and extends along the inside perimeter of the side wall  16  of the structure  12 . Preferably, the chain track  98  has a pair of spaced rails  101  that reduces the chance of derailment. Moveably attached to the chain track  98  are a pair of tractor drive assemblies  100  positioned  180  degrees in relation to the other. Brackets  102  are attached to the outer ends of both the tine support bar  60  and the auger support bar  62  and towing rods  104  are pivotally connected to and extend between the brackets  102  and the tractors  100 . The tractor drive assemblies  100  travel along the chain track  98  on the inside perimeter of the side wall  16  of the structure  12  to rotate the tine assembly  64  and the auger assembly  76  about the first tube  40  within the structure  12 . 
     Connected to an inner end of the rotatable tine assembly  64  is a third motor  106  that drives the rotation and direction of the tine assembly  64  and attached to the inner end of the auger assembly  76  is a fourth motor  108  that drives the rotation and direction of the auger  80 . The third motor  106  and fourth motor  108  are connected to a control system  110  that is adapted to control, either manually or automatically, the rotational speeds and direction of rotation of the tine assembly  64  and the auger assembly  76  respectively. The control system  110  preferably is equipped with switches, multiple speed drive, variable speed drive, and/or Variable Frequency Drives or the like to operate and control the drying assembly  10  including the rotation, speed, travel direction, raising/lifting and lowering of various components of the drying system  10 . In one example, the control system  110  is positioned adjacent the access door  36 . 
     The fan  27  and heater/burner  28  are connected to a second control system  112  that is adapted to manually or automatically control the temperature and the flow rate of the air that flows through the air duct  30  to dry the biomass. Also, a plurality of sensors or monitors  114  are positioned both within the structure  12  and outside the structure that measure air temperature, humidity, and biomass moisture. As one example, sensors  114  are positioned to measure the temperature and humidity of the saturated air exiting the biomass layer. Temperature and humidity will vary based on the incoming moisture content of the biomass, the desired final moisture content of the biomass, and the ambient conditions. The sensors  114  are connected to both the first and second control systems  110  and  112 . There is also a safety control panel  113  with safety switches that are used for safe operation of the drying assembly  10 . 
     Positioned below the drying floor  20  and connected about the first tube  40  is a discharge hopper  116 . A pair of discharge flaps  118  are positioned above the discharge hopper  116  and selectively open and close an opening  120  in the drying floor  20 . The discharge flaps  118  are flush with the drying floor  20 . Connected to the discharge flaps  118  is an activator  122  that moves the flaps  118  between an open and closed position. The activator  122  is connected to the control system  110  or it can be manually operated. Biomass storage sacks (not shown) are positioned under the discharge hopper  116  or alternatively a conveyor (not shown) is positioned under the discharge hopper to collect and convey dried biomass from the structure  12 . 
     In operation, wet biomass is positioned inside the structure  12  on the drying floor  20 . In one example, wet biomass is transported into the structure via a portable conveyor and deposited on the drying floor  20 . The drop point of the biomass material may be at the center of the structure  12 , at the outer perimeter of the structure  12 , or somewhere in between. The drying system  10  is then activated using both control systems  110  and  112 . The tractor drive assembly  100 , which is connected to the control system  110 , once activated begins to move along the chain track  98  in a first, or forward direction. As the tractor  100  moves forward, the tow rod  104  follows, which causes the tine assembly  64  and the auger assembly  76  to rotate about the center of the structure  12 . Both the speed of rotation about the center of the structure and the direction of movement, forward or backward, are adjustable by the control system  110 . The fan  27  and heater/burner  28  are also activated by the control system  112 . Based upon information provided by the sensors  114  the control system adjusts the temperature and air flow based upon the incoming moisture content of the biomass and the desired ending moisture content of the biomass, along with conditions inside the structure and ambient conditions outside the structure, and determines when to adjust the temperature, adjust the air flow, switch off the burner, and when to stop the drying operation. 
     In a first mode, or spreading mode, of operation, the drying assembly  10  is positioned to engage the biomass material by activating the first motor  50  to lower the lift assembly  38  so that the drying assembly engages and spreads the biomass material from the drop point inside the biomass loading door  34  to cover the entire drying floor  20 . In the spreading mode, the control system  110  activates the tractor drive assembly  100  to move the tine assembly  64  and auger assembly  76  about the structure  12  in a first or forward direction. The control system  110  also activates the third motor  106  causing the tine assembly  64  to rotate in a counter or backward direction where the tines  72  engage the biomass to move the biomass forward in front of the shaft  66  (or the direction the tine assembly  64  is moving) while the tines move up and over the shaft  66 . The auger assembly  76  also is activated by the control system  110 , through the activation of the fourth motor  108 , to engage the biomass. The direction of rotation of the auger  80  is determined by the position of the biomass. To move the biomass inward toward the center of the structure  12  the auger  80  is rotated in a counter or backward direction where the biomass is moved forward in front of the auger  80  while the auger continues to rotate upward and over toward the backboard  92 . To move the biomass outward toward the side wall  16  and outer perimeter of the structure  12 , the auger is rotated in a concurrent or forward direction where the biomass is moved backward of the auger  80  toward the backboard  92  as the auger rotates downward and then toward the backboard. While the tine assembly  64  is not necessary in the spreading mode, the use of the tine assembly accelerates the spreading process. 
     Once the biomass material is spread across the drying floor, in a second mode of operation, the biomass material is levelled to enhance uniform drying through the biomass layer. Using the control system  110 , the first motor  50  is activated so that the lift assembly  38  positions the tine assembly  64  and auger assembly  76  so that the tines  72  are partially inserted into the biomass material. Once positioned, the control system  110  activates the third motor  106  to rotate the tine assembly  64  and the second motor  95  to lift the auger assembly  76  to a raised position where the auger does not engage the biomass material. Finally, the control system  110  activates the tractor drive assembly  100  to rotate the drying assembly  10  about the first tube  40  in a forward direction. This produces a “rolling wave” of biomass ahead of the shaft  66  which fills in the voids in the surface of the biomass as the drying assembly is moved  360  degrees around the structure  12 . 
     Based upon information received from the sensors  114 , the control system  110  determines when the biomass needs to be stirred. To activate the third mode of operation, or the stirring mode of operation, the control system  110  activates the first motor  50  causing the lift assembly  38  to position the tine assembly  64  so that the tines are inserted into the biomass. Then, the control system  110  activates the second motor  95  to raise the auger assembly  76  using the auger lift assembly  93  if not already in a raised position. The third motor  106  is then activated by the control system  110  to rotate the tine assembly  64  in a concurrent or forward direction wherein the tines  72  engage the biomass and move the biomass backwards behind the shaft  66  while the tines  72  continue upward and over the shaft. Finally, the control system  110  activates the tractor drive assembly  100  to rotate the drying assembly  10  about the first tube  40  in a forward direction. The stirring mode stirs the biomass material, breaking up packed concentrations of material resulting in more uniform distributions of the biomass for more efficient drying. To reduce over stirring, a reduced number of tines  72  are attached to the mounting tube  70 . 
     Once the biomass is dried to a desired moisture level, the control system  110  activates a fourth mode, or unloading mode, of operation. To activate the unloading mode the control system  110  lowers the auger assembly  76  through the activation of the second motor  95  and the auger lift assembly  93 . The discharge flaps are then opened  118  and the control system  110  activates the fourth motor  108  which causes the auger  80  to rotate in a concurrent or forward direction. Finally, without activating the third motor  106 , the control system  110  activates the tractor drive assembly  100  to cause the drying assembly to rotate about the first tube  40  in a forward direction. The control system also activates the fourth motor  108  to rotate the auger  80  to move the biomass material inward toward the center of the structure in a counter or forward directions where the biomass is moved in front of the auger  80 . The auger  80  transports dried biomass material toward the discharge flaps where the material falls through the opening  120  in the drying floor  20  and into the discharge hopper  116 . 
     The tractor drive assembly  100 , the third motor  106 , and the fourth motor  108 , are of any type and in one embodiment the control system  110  includes a Variable Frequency Drive (VFD). The control system  110  is adapted to adjust or change the linear or track speed of the tractor drive assembly  100  and can also move the tractor drive assembly  100  in either a forward or backward direction. The control system  110  also is adapted to vary the direction and rotational speed of the third  106  and the fourth  108  motors. 
     Accordingly, a hemp biomass drying assembly  10  has been disclosed that at the very least, meets all of the stated objectives. From the above discussion and accompanying figures and claims it will be appreciated that the hemp biomass drying assembly  10  offers many advantages over the prior art. It will be appreciated further by those skilled in the art that other various modification could be made to the device without parting from the spirit and scope of this invention. All such modifications and changes fall within the scope of the claims and are intended to be covered thereby. It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in the light thereof will be suggested to persons skilled in the art and are to be included in the spirit and purview of this application.