CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable to this application.

STATEMENT REGARDING FEDERALLY

SPONSORED RESEARCH OR DEVELOPMENT

Not applicable to this application.

BACKGROUND

Field

Example embodiments in general relate to a plant drying system for efficiently and uniformly removing moisture from a plant material such as hemp or marijuana.

Related Art

Any discussion of the related art throughout the specification should in no way be considered as an admission that such related art is widely known or forms part of common general knowledge in the field. Plant drying systems, and more particularly, systems for drying hemp or marijuana, have existed for many years. For example, drying hemp or other plant material in the field typically yields inconsistent results, and may allow for pest and bacteria growth. Direct fired gas dryers can take longer to dry the material, and also exposes it to high temperatures. Further, hot air drying rooms also take a lot of time, and generally produce inconsistent results.

SUMMARY

An example embodiment is directed to a plant drying system. The plant drying system and method includes loading plant material into a chamber of a vessel, agitating the plant material within the chamber with an agitator, and applying microwave energy to the plant material within the chamber by a microwave generator. In some example embodiments, the material may be agitated by an agitator extending into or through the chamber. The method further may include detecting a temperature — for example, by using a resistance temperature detector, of the plant material within the chamber by a temperature sensor, monitoring a temperature of the plant material within the chamber by a control unit, and adjusting a level of applied microwave energy by the control unit so as to maintain the temperature of the plant material within a desired temperature range.

Further, the method and system may include using a load cell to detect the weight of the plant material within the chamber, determining the moisture level of the plant material within the chamber by the control unit based on the weight of the plant material, and unloading the plant material from the chamber when the moisture level of the plant material is detected within a desired moisture range.

In an example embodiment, the method may further comprise the step of discharging water vapor from the vessel through an air outlet. Moreover the temperature sensor may comprise an infrared sensor instead of, or in addition to, a resistance temperature detector. In still other example embodiments of the system, the agitator comprises a shaft and paddles extending outwardly from the shaft. The frequency of the microwave generator comprises 915mHz or 2450mHz, although other frequencies are also possible. The plant material being dried may be comprised of hemp or marijuana. Further, the control unit may comprise a microprocessor or microcontroller. The method of drying plant material may further comprise the step of drawing moisture out of the chamber, such as with a fan system, while carrying out any or all of the other steps discussed herein.

During drying, the temperature of the plant material is monitored by IR sensors and resistance temperature detector, with the inputs being processed by a control unit and converted to usable temperature data. The control unit can use the temperature data to control and maintain the drying temperature at a desired temperature. For example, a user may determine that a particular temperature works well for a certain plant material, and that temperature may be used as a setpoint. In addition to temperature, the evaporation rate of the material can also be maintained, by monitoring the weight change as measured by load cells and input to the control unit. Either the temperature or evaporation rate, or both, may be used as inputs to the control unit to adjust and maintain the parameters by controlling the microwave energy produced by microwave generator.

The control unit may constantly or periodically monitor the moisture level of the plant material by using the inputs from load cells. Once the moisture level of the plant material reaches a desired level, the control unit may stop the microwave generator. Further, the agitator may be deactivated and an outlet valve may be opened to discharge material from a material outlet. There has thus been outlined, rather broadly, some of the embodiments of the plant drying system in order that the detailed description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional embodiments of the plant drying system that will be described hereinafter and that will form the subject matter of the claims appended hereto. In this respect, before explaining at least one embodiment of the plant drying system in detail, it is to be understood that the plant drying system is not limited in its application to the details of construction or to the arrangements of the components set forth in the following description or illustrated in the drawings. The plant drying system is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will become more fully understood from the detailed description given herein below and the accompanying drawings, wherein like elements are represented by like reference characters, which are given by way of illustration only and thus are not limitative of the example embodiments herein.

Figure 1 is a side view of a plant drying system in accordance with an example embodiment.

Figure 2 is a side cutaway view of a plant drying system in accordance with an example embodiment.

Figure 3 is a side cutaway view of plant material being inserted into a plant drying system in accordance with an example embodiment.

Figure 4 is a side cutaway view of plant material being agitated within a plant drying system in accordance with an example embodiment.

Figure 5 is a side cutaway view of plant material being irradiated by a plant drying system in accordance with an example embodiment.

Figure 6 is a side cutaway view of gas being discharged from a plant drying system in accordance with an example embodiment.

Figure 7 is a side cutaway view of dried plant material being discharged from a plant drying system in accordance with an example embodiment. Figure 8 is a block diagram of a plant drying system in accordance with an example embodiment.

Figure 9 is a flowchart illustrating insertion and agitation of a plant material within a vessel of a plant drying system in accordance with an example embodiment.

Figure 10 is a flowchart illustrating irradiation of a plant material within a vessel of a plant drying system in accordance with an example embodiment.

Figure 11 is a flowchart illustrating temperature maintenance of a plant material within a vessel of a plant drying system in accordance with an example embodiment.

Figure 12 is a flowchart illustrating moisture level detection of a plant material within a vessel of a plant drying system in accordance with an example embodiment.

Figure 13 is a flowchart illustrating discharge of dried plant material from a plant drying system in accordance with an example embodiment.

DETAILED DESCRIPTION

A. Overview.

An example plant drying system 10 generally comprises a vessel 20 having a chamber 30 for receiving a volume of a plant material 12, a microwave generator 60 for applying microwave energy to the plant material 12 within the chamber 30, and a temperature sensor 38 for detecting a temperature of the plant material 12 within the chamber 30. The system 10 may also include one or more load cells 52 for detecting a weight of the plant material 12 within the chamber 30. The system 10 may further include a control unit 70 for monitoring the weight, moisture content, and temperature of the plant material 12 within the chamber 30, the control unit 70 being capable of automatically adjusting a level of microwave energy applied to the plant material 12 so as to maintain the temperature of the plant material 12 within a desired temperature range, the control unit 70 being further adapted to determine a moisture level of the plant material 12 within the chamber based on the weight of the plant material 12 as measured by load cells 52.

B. Vessel.

As best shown in FIGS. 1-7, the plant drying system 10 may comprise a vessel 20 in which plant materials 12 may be processed, such as by tumbling, mixing, agitating, drying, and/or exposing to electromagnetic radiation, and then discharged. The shape, structure, size, and configuration of the vessel 20 may vary in different embodiments, and thus should not be construed as limited by the exemplary figures. In the exemplary embodiment shown in FIGS. 1 -7, the vessel 20 is illustrated as comprising an upper end 21, a lower end 22, a first side 23, and a second side 24. The vessel 20 may stand upright using one or more support legs 26 such as shown in FIGS. 1 -7. To measure the weight of the vessel 20 and its contents, the system 10 may include load cells 52 upon which the legs 26 rest. In other embodiments, the vessel 20 may be positioned directly on a surface, or may include a frame or base on which it rests.

As also shown in FIGS. 1 -7, the vessel 20 includes an internal chamber 30 which, during certain times, may be kept under slight negative pressure to remove moisture from the chamber, such as with an exhaust system (not shown). The chamber 30 may be accessible by various inlets 31, 35 and outlets 33, 36 such as shown in FIG. 1. By way of example and without limitation, the chamber 30 may comprise a material inlet 31, a material outlet 33, an air inlet 35, and an air outlet 36

The material inlet 31 of the vessel 20 is utilized to receive the plant material 12 to be processed such as shown in FIG. 2. The material inlet 31 may include an inlet valve 32 for selectively sealing the material inlet 31. Such a valve is necessary to isolate the interior of the vessel 20 from the outside environment, especially when the air outlet 36 is used to draw air and moisture out of the chamber 30 to speed the drying process. When drying is complete, plant materials 12 may be discharged through the material outlet 33. The material outlet 33 may include a discharge valve 34 for selectively opening and closing the material outlet 33, which also serves to seal and isolate the interior of the vessel 20 when closed. FIGS. 1-7 illustrate an exemplary embodiment in which the material inlet 31 is positioned on the upper end 21 of the vessel 20 and the material outlet 33 is positioned on the lower end 22 of the vessel 20. In such a configuration, the plant materials 12 utilize gravity, as well as agitation, for transfer from the material inlet 31 into the chamber 30 and, eventually, out of the chamber 30 via the material outlet 33.

It should be appreciated that in alternate embodiments, the material inlet 31 and material outlet 33 may be positioned at alternate locations on the vessel 20. For example and without limitation, the material inlet 31 could be positioned on the first side 23 of the vessel 20 and the material outlet 33 could be positioned on the second side 24 of the vessel 20. In such an embodiment, a conveyor, auger, or agitator 40 may aid in transferring the plant material 12 between the material inlet 31 and the material outlet 33.

The air inlet 35 and air outlet 36 may be utilized to transfer gas such as air or water vapor into or out of the chamber 30 of the vessel 20. For example, the air inlet 35 can be opened to allow fresh air to enter the chamber 30. As another example, the air outlet 36 may be utilized to draw air and moisture out of the chamber 30. Gas discharge 16, such as water vapor that has been removed from the plant material 12 by the drying process may be discharged through the air outlet 36 as shown in FIG. 6.

FIGS. 1-7 illustrate an exemplary embodiment of the system 10 in which the air inlet 35 and air outlet 36 are both positioned on the upper end 21 of the vessel 20. It should be appreciated that the air inlet 35 and air outlet 36 could be positioned in various locations along the vessel 20. In some embodiments, the air inlet 35 may be on a different end 21, 22 or side 23, 24 of the vessel 20 than the air outlet 36.

As best shown in FIGS. 2-3, the chamber 30 may have within it an agitator 40, comprising a shaft 42 and attached agitator paddles 44, which serve to agitate any product within the chamber 30, which in turn aids in drying the material 12 and distributing heat and energy uniformly, to avoid over processing some material and under processing other material. Although the agitator 40 shown has a generally horizontal shaft, other configurations are possible. The agitator shaft 42 may be driven by one or more motors and gearboxes comprising a drive assembly 46. In the embodiments shown in FIGS. 1-7, the drive assembly 46 comprises two motor/gearbox combinations, one on each end of shaft 42, mounted on the outside of the chamber 30. Other drive configurations are also possible.

The vessel 20 may also include numerous sensors, such as infrared sensors 38, ultraviolet sensors 37, resistance temperature sensor 50, and load cells 52. As discussed below, these sensors provide inputs to control unit 70, which uses them to control the drying process and to ensure uniform results. Specifically, the control unit 70 can monitor and control the temperature to reach and maintain a target temperature by controlling the microwave generator 60, which supplies energy to the chamber 30 via waveguide 62. The energy from generator 60 may be controlled, for example, by controlling the power level, or by changing an on/off duty cycle of the generator 60. C. Control Unit.

FIG. 8 is a block diagram illustrating an exemplary control unit 70 being communicatively interconnected with various components of the plant drying system 10, including the ultraviolet sensors 37, infrared sensors 38, drive assembly 46 of the agitator 40, resistance temperature detector 50, load cells 52, microwave generator 60, and inlet valve 32 and discharge valve 34. The control unit 70 may be adapted to receive, process, and send data or inputs and outputs as described herein.

A control unit 70 may be comprised of any conventional computer, or it may also be a programmable logic controller (PLC). A PLC lends itself naturally to this application because it is relatively easy to program and has outputs that can be used to control the plant drying system 10, such as for valve control, microwave power control, etc. A PLC may also readily accept inputs that are needed for the plant drying system 10, such as inputs from sensors 37, 38, and 52 mounted on the vessel or its support legs, as shown in FIGS. 1 -8.

As mentioned, a PLC can receive inputs and create outputs as needed to control the drying process automatically, based on the inputs. To do so, the control unit 70, in this case a PLC, may receive, either automatically or via manual inputs, the weight and moisture content of a batch of plant material 12 to be dried.

The PLC or other control unit 70 may also include a Human-Machine Interface (HMI) 72 to provide users with the capability to program and use the system, and to serve as an interface with control unit 70. As shown in FIG. 8, HMI 72 provides a display for users to monitor the status and functioning of the drying system 10, and a touch screen to allow for human input. FIG. 8 also shows other interconnections of the system, as well as inputs and outputs of the control unit 70. These inputs and outputs are used by the control unit 70 to carry out the steps described herein, although some or all steps may also be performed manually.

In addition to the general control of the drying process, the system 10 may include UV sensors 37. These sensors are used to detect arcing inside the chamber 30. For example, arcing inside the chamber may occur when microwave energy is applied if the material loaded into it has foreign objects, is grossly undersized, or if the wrong material (e.g., lactose powder) is accidentally loaded into the chamber. If such arcing is detected, the control unit 70 may stop the drying process immediately, and deactivate the microwave generator 60.

As indicated in FIGS. 9-13, the HMI 72 can be used to manually control any of the steps shown to operate the drying system 10, and alternatively, the HMI 72 and control unit 70 can automatically perform any or all of the steps. As just one example, control unit 70 may continuously or periodically monitor the weight, and thus the moisture content, of a batch of plant material 12 to be dried, using inputs from the load cells 52. The control unit 70 may also be used to control the temperature, either of the plant material 12 being processed, the interior of the chamber 30, or both. The user may determine what temperature is optimal based on any desired parameters, including but not limited to batch size, initial moisture content, past results, etc. The desired operating temperature may be entered by a user or by other means, and input into the control unit 70 via HMI 72. A conventional computer may also serve as the control unit 70. Such a conventional computer preferably includes a display screen (or monitor), a hard disk drive, a network interface, and a keyboard. A conventional computer also includes a microprocessor, a memory bus, random access memory (RAM), read only memory (ROM), a peripheral bus, and a keyboard controller. The microprocessor may be a general-purpose digital processor that controls the operation of the computer. The microprocessor can be a single-chip processor or implemented with multiple components. As described above regarding a PLC used as the control unit 70, a conventional computer can also receive inputs from the sensors of the drying system 10 and control the overall process, as well as driving an HMI 72.

Using instructions retrieved from memory, the microprocessor controls the reception and manipulations of input data and the output and display of data on output devices. The memory bus is utilized by the microprocessor to access the RAM and the ROM. RAM is used by microprocessor as a general storage area and as scratch-pad memory, and can also be used to store input data and processed data. ROM can be used to store instructions or program code followed by microprocessor as well as other data. A peripheral bus is used to access the input, output and storage devices used by the computer. In the described embodiments, these devices include or may include a display screen, a printer device, a hard disk drive, and a network interface. A keyboard controller is used to receive input from the keyboard and send decoded symbols for each pressed key to a microprocessor over a bus. The keyboard is used by a user to input commands and other instructions to the computer system. Other types of user input devices can also be used in conjunction with the plant drying system. For example, as discussed above, an HMI comprising a touch screen, or pointing devices such as a computer mouse, a track ball, a stylus, or a tablet to manipulate a pointer on a screen of the computer system may be used. The display screen is an output device that displays images of data provided by the microprocessor via the peripheral bus or provided by other components in the computer. The hard disk drive can be utilized to store various types of data. The microprocessor together with an operating system operate to execute computer code and produce and use data. The computer code and data may reside on RAM, ROM, or hard disk drive.

The computer code and data can also reside on a removable program medium and loaded or installed onto computer system when needed. Removable program mediums include, for example, CD-ROM, PC-CARD, USB drives, floppy disk and magnetic tape. The network interface circuit is utilized to send and receive data over a network connected to other computer systems. An interface card or similar device and appropriate software implemented by microprocessor can be utilized to connect the computer system to an existing network and transfer data according to standard protocols.

D. Operation of an Example Embodiment.

In use, a specified amount of material to be dried is loaded into the vessel 20. As outlined in FIG. 9, the material may be loaded according to weight or volume, and further, its moisture content may be known or measured, such as measuring the weight of the material for a given volume. As stated above, these parameters may be measured with sensors and automatically loaded into the memory of control unit 70, or they may be entered, along with any other parameters, by a user by way of HMI 72. If the material 12 is loaded by weight rather than volume, the initial, moist weight may be measured by load cells 52. As an example, the weight of the system 10 with an empty chamber may be known, and thus subtracted from the loaded weight so that the weight of just the plant material 12 may be known and stored in a memory of control unit 70. Further, the moisture content of the material 12 may be determined based on its measured weight and its volume, either measured, sensed, or input.

The material 12 may be loaded into the material inlet 31 by way of inlet valve 32, which may be operated by an output from control unit 70. The material 12 may be loaded from another system or component, such as by a conveyor that may be independently controlled, or controlled by control unit 70. After loading, valve 32 is closed. Once the material 12 is loaded, the paddle agitator 40 may be rotated at 280 fpm, for example, to generate an agitated bed of moist plant material 12 to be dried. The paddle agitator 40 may be made of stainless steel, and is used generally to create a consistent material flow path within the chamber 30 to promote uniform exposure to the microwave energy, and to evenly equilibrate particle temperature through conductivity, thereby creating a uniform temperature across the entire mass of processed material 12.

Next, as outlined in FIG. 10, the controller may start the drying process by activating microwave generator 60, which delivers microwave energy to the chamber 30 via waveguide 62, as shown in FIGS. 1-7. The generator 60 generates microwave energy generally in one of two different frequencies applicable for industrial use: 915 MHz or 2450 MHz, although other frequencies are possible. As a result of the energy, water evaporates from plant material 12. The water vapor and also air can be removed from the chamber through air outlet 36, while air inlet 35 admits fresh air into the chamber. Generally, the air inlet and outlet will be open at the same time.

As indicated by FIG. 11, during drying, the temperature of the plant material 12 is monitored by IR sensors 38 and resistance temperature detector 50, with the inputs being processed by control unit 70 and converted to usable temperature data. As discussed above, the control unit 70 can use the temperature data to control and maintain the drying temperature at a desired temperature. For example, a user may determine that a particular temperature works well for a certain plant material 12, such as 212° F. In addition to temperature, the evaporation rate of the material can also be maintained, by monitoring the weight change as measured by load cells 52 and input to control unit 70. Either temperature or evaporation rate, or both, may be used as inputs to the control unit 70 to adjust and maintain the parameters by controlling the microwave energy produced by microwave generator 60.

Control unit 70 may constantly or periodically monitor the moisture level of the plant material 12 by using the inputs from load cells 52 as described above. Once the moisture level of the plant material 12 reaches a desired level, such as 10% by way of example, the control unit 70 may stop the microwave generator 60, as indicated along with other steps, in FIG. 12. Further, the agitator 40 is deactivated and the outlet valve 34 may be opened to discharge material 12 from material outlet 33. The volume of dried plant material 12 may be unloaded through the outlet 33 for further processing. For example, from outlet 33, the material 12 may be input directly to a packaging system, or it may be fed to a conveyor. The foregoing steps are outlined generally in FIG. 13. It should be noted, however, that the steps listed in FIG. 13 and other flowcharts herein do not necessarily represent the order of processing. For example, the control unit 70 may activate the agitator 40 for a time after the outlet valve 34 is opened in order to aid in the discharge of material 12 from the chamber 30.

Once a batch is dried and has been discharged, the control unit 70 may ensure that all outputs and corresponding mechanisms are in an initial condition in order to repeat the process for the next batch of material 12. For example, the control unit 70 may deactivate generator 60, close valve 34, open valve 32, and deactivate agitator 40.

The method and system may be used to improve over existing drying techniques and equipment. For example, drying hemp or other products in the field typically yields inconsistent results, and may allow for pest and bacteria growth. Direct fired gas dryers can take longer to dry the material, and also exposes it to high temperatures. Further, hot air drying rooms also take a lot of time, and generally produce inconsistent results.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the plant drying system, suitable methods and materials are described above. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety to the extent allowed by applicable law and regulations. The plant drying system may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive. Any headings utilized within the description are for convenience only and have no legal or limiting effect.