Abstract:
The portable sugar mill is established on a mobile platform for transport to the harvesting field, so that the juice of the harvested sugar cane may be processed and refined in the field. The portable sugar mill converts the juice, which contains sucrose, into raw sugar crystals (brown sugar) and molasses. The portable sugar mill includes a separator tank, a pre-heating tank, a clarifier, and three successive stages of evaporative crystallization and separation of crystals from syrup. The portable sugar mill has a programmable logic controller and a plurality of sensors, control relays, pumps, motors, heaters, and valves that operate automatically under direction of the programmable logic controller.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/575,284, filed Aug. 19, 2011. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to sugar mills, and more specifically to a portable sugar mill for in-field processing of cane juice to brown sugar and molasses. 
         [0004]    2. Description of the Related Art 
         [0005]    Sugar is one of the most basic ingredients present in the kitchens of most homes. It imparts the sweet flavor that many enjoy from drinks, candy, and desserts to savory dishes. One of the most common types of sugars consumed by the general public is sucrose, derived from sugar cane. 
         [0006]    One of the biggest concerns with the above is the potential loss of raw material for juice extraction, i.e., not the sugar cane itself but the contents therein, Sugar cane, once cut, must be expeditiously transported to the processing plant because the cut cane begins to lose its sugar content. This issue is exasperated by the damage inflicted on the cane during mechanical harvesting since it accelerates the decay. Although my cane juice extractor, described in U.S. Pat. No. 7,918,160, issued Apr. 5, 2011, is capable of pressing juice from the cane stalks, the issue still remains that the cane juice must be transported to a sugar processing plant, which consumes time, energy, and resources from various entities. 
         [0007]    The cane grower and harvest must exhaust time and resources in harvesting, and juicing the cane stalks, yet he must then contain the extracted juice and transport the juice to a processing plant or mill. Governmental entities must burden resources for road maintenance and services to the transportation vehicles, as well as establishing transportation laws and guidelines that allow the safe transport of the juice, as well as providing safety for everyone using the transportation system infrastructures. The plant or mill must utilize resources for maintaining and operating facilities, as well as provide processing services for the juice providers. 
         [0008]    Thus, a portable sugar mill solving the aforementioned problems is desired. 
       SUMMARY OF THE INVENTION 
       [0009]    The portable sugar mill is a mobile processing plant that converts the juices extracted from sugar cane into brown sugar and molasses in the field, without the necessity of transporting either the raw sugar cane or the extracted juices to a stationary mill for processing. The portable sugar mill is an all-electric unit that can be mounted on an 8′×42′ flat-bed truck. The truck includes a flat-bed frame and a forward deck. The forward deck includes a power source for the portable sugar mill processes. The flat-bed frame has an inlet side where extracted cane juice may be fed. The power source of the forward deck also includes a controller/generator connected to a fuel source. 
         [0010]    These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a portable sugar mill according to the present invention. 
           [0012]      FIG. 2  is a top plan view of a portable sugar mill according to the present invention. 
           [0013]      FIG. 3  is a block diagram of the control system of a portable sugar mill according to the present invention. 
           [0014]      FIGS. 4A ,  4 B,  4 C, and  4 D are a block diagram of the process stages of a portable sugar mill according to the present invention. 
       
    
    
       [0015]    Similar reference characters denote corresponding features consistently throughout the attached drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The portable sugar mill is a mobile processing plant that converts the juices extracted from sugar cane into brown sugar and molasses in the field, without the necessity of transporting either the raw sugar cane or the extracted juices to a stationary mill for processing. The portable sugar mill is an all-electric unit that can be mounted on an 8′×42′ flat-bed truck, a trailer, a wagon, or other portable platform. The truck includes a flat-bed frame and a forward deck. The forward deck includes a power source for the portable sugar mill processes. The flat-bed frame has an inlet side where extracted cane juice may be fed. The power source of the forward deck also includes a controller/generator connected to a fuel source. 
         [0017]    In  FIGS. 1 and 2  the portable sugar mill  10  is shown mounted on a towable wagon or trailer  12  having a hitch member  14  for coupling to a towing vehicle (not shown). The trailer  12  is supported by a plurality of wheels  16 . As mentioned above, the sugar mill  10  may also be mounted on a flat-bed truck. 
         [0018]    The trailer  12  has a forward deck  18   a  and a main deck  18   b . The forward deck  18   a  supports a power supply  8 , and a system controller, such as a programmable logic controller  4 . In addition, the power supply  8  has a fuel source  8   a  for operating the power supply to generate electricity. It is well understood that the power supply  8  and fuel source  8   a  may be a conventional generator powered by an internal combustion engine, or a generator powered by alternative fuels and/or power sources, such as fuel cells, batteries and/or solar panels. 
         [0019]    The main deck  18   b  supports the processing system  10 . The processing system  10  has a plurality of components to carry forth the process of refining raw sugar cane juice into crystallized sugar product and molasses. The components are provided in a sequential flow operation, as shown in  FIGS. 4A through 4D , thereby carrying out a complete sugar refining plant process in the field. 
         [0020]    The portable sugar mill  10  does not include rollers, mills, cutters, or other devices for extracting juice from sugar cane. Rather, the input to the portable sugar mill is juice that has already been extracted from sugar cane by an in-field extractor or by a portable extractor. The portable sugar mill  10  may be used in conjunction with a portable cane juice extractor, such as the device described in my previous patent, U.S. Pat. No. 7,918,160, issued Apr. 5, 2011 (the contents of which are hereby incorporated by reference in their entirety), which describes a portable device that extracts the raw juice from sugar cane on site. The portable sugar mill has a separator tank  20  that receives the sugar cane juice from the juice extraction device. The separator tank  20  has a float sensor that detects the liquid level in the tank  20 , and an inlet valve that may be connected to the juice extractor by a pump hose or the like. A control relay connected to the programmable logic controller (PLC)  4  opens the valve and turns on a pump to draw the juice into the separator tank  20 , The PLC closes the inlet valve under automatic control when the float tank is full. The juice is kept in the separator tank  20  for a period of time to allow solids to settle to the bottom of the tank  20 . After the solids have settled, the PLC opens an outlet valve and turns on a pump that transfers the juice to a pre-heating tank (PHT)  22 . Slaked lime (calcium hydroxide) is added to the liquid, which is heated to a predetermined temperature (preferably about 170° F.) by a heater under thermostatic control. The sugar mill  10  may have a dispenser containing the slaked lime, which includes a valve and a control relay operating under automatic control of the PLC  4  for dispensing a metered amount of the slaked lime into the pre-heating tank  22 . The sucrose is then transferred from the PHT  22  to a clarifier tank  24 , which agitates and mixes the warmed sucrose with a polymer (released into the tank  24  by a PLC-controlled valve) using a motor  24   a  that operates a stirrer. The lime destroys non-crystallizable invert sugars and amino acids in the clarifier tank  24 , and the polymer helps to flocculate impurities. The clarified juice is transferred to a clarified sucrose holding tank  26  by PLC-controlled inlet and float valve(s) and pump(s). The holding tank  26  maintains the clarified juice at a predetermined temperature (preferably 170° F.) using another heater under thermostatic control. 
         [0021]    The process continues with a first boiler  28 , the first boiler  28  receives the clarified juice and boils off water to concentrate by evaporation under pressure. The pressure is applied by a vacuum pump  28   a  operated under control of the PLC  4 , which applies a negative pressure of about −25 psi to the boiler  28 . The operator adds seed crystals to the boiler  28  and views crystal growth through a sight glass in the boiler  28 . When the crystals are of an appropriate size, the operator presses a stop button, which shuts off the heaters, opens an outlet valve, and activates a pump that transfers the partially crystallized juice to a first crystallizer  30 . The FC  30  provides a stirring and cooling function to complete crystallization. The resulting mix of crystals and syrup, called massecuite, is transferred to a first centrifuge  32 . 
         [0022]    In the first centrifuge  32 , the PLC  4  turns on a centrifuge motor that provides a spinning operation that causes separation of the syrup from the crystals. Upon completion of the separation by the first centrifuge  32 , the syrup is transferred out of the first centrifuge  32  for further processing, while the crystalline solids that remain are stored in the first centrifuge  32 , subsequently being removed by dumping the crystals into an auger system to a hopper for packaging as (A pan) sugar, or sent as bulk raw sugar to a refinery for further processing. 
         [0023]    The syrup from the first centrifuge  32  is transferred to a second boiler  34 . The second boiler  34  receives the syrup and boils the syrup under pressure to cause further evaporation of water from the syrup, seed crystals being added to initiate further crystallization. The output of the second boiler  34  is transferred a second crystallizer  36 . The second crystallizer  36 , like the first crystallizer  30 , provides a stirring and cooling function to complete crystallization that produces a second massecuite, which is transferred to a second centrifuge  38 . 
         [0024]    The second centrifuge  38  provides another spinning operation that causes separation of the liquid portion of the massecuite from the solid or crystalized portion. Upon completion of the separation by second centrifuge  38 , the liquid portion of the massecuite is transferred out of second centrifuge  38  for further processing, while the crystalline solids (B pan sugar) that remain are removed and transferred to the syrup entering the first boiler  28 . 
         [0025]    The syrup from second centrifuge  38  is transferred to a third boiler  40 . The third boiler  40  receives the syrup and boils the syrup under pressure to cause still further evaporation of water from the syrup and initiate further crystallization. The output of the third boiler  40  is transferred to a third crystallizer  42 . The third crystallizer  42  provides stirring and cooling to complete crystallization. The resulting third stage massecuite is transferred to a third centrifuge  44 . Crystals (pan C sugar) that drop out of the third centrifuge  44  are added to the syrup entering the second boiler  34 . The syrup left over from the third centrifuge  44  is transferred to a holding tank  46 . The content of the holding tank  46  is blackstrap molasses, which is sold as a sweetener for animal feed. 
         [0026]    As seen in  FIG. 2 , and  FIGS. 4A through 4D , a conduit system  50  is provided between each portion of the processing of the portable sugar mill  10 . Also included in the conduit system  50  are a plurality of pumps  52  for pumping the sucrose/massecuite through the different stages of the milling process. 
         [0027]      FIG. 3  shows the basic function of the control segment of the system  10 . Throughout the system there are several transducers and/or sensors  2 , for providing information or data to be processed. The sensors  2  include volume level (such as float sensors within each of the tanks) sensors, temperature sensors, valve position sensors, as well as a myriad of other types of transducers to indicate an instantaneous operational status to the programmable logic controller  4 . 
         [0028]    Taking  FIG. 3  in conjunction with  FIGS. 4A through 4D , more details of each of the functioning components of system  10  is explained. Each tank ( 20 - 46 ) has at least one sensor  2  associated with it for providing state information or data to the programmable logic controller  4 . The programmable logic controller  4  receives the state information or data at an input  4   a , the input  4   a  presents the data to the central processor unit (CPU)  4   b  or microcontroller. The CPU  4   b  includes computation, memory, look-up registers, etc. (all not shown, but well known in the art). The CPU  4   b  determines the next operation to be completed, based upon the received data from input  4   a . The CPU  4   b  initiates instructional signals via an output  4   c  to an actuator  6   a  (e.g., control relays). The actuator  6   a  receives the instructional signals from output  4   c , and sends the instruction to the corresponding load  6   b  (pumps, valves, motors, etc.). In addition, the power supply  8  generates the operational power for the programmable logic controller  4 , the actuator  6   a , and loads  6   b . The loads  6   b  are the various portions of each of tanks ( 20 - 46 ), that are controlled by the programmable logic controller  4 , in the processing of the sucrose/massecuite into sugar. The loads  6   b  include heating elements, motors, valves, pumps, etc. 
         [0029]    Referring to  FIG. 4A , separation tank  20  has, at an inlet, a first filter  20   a , for removing large and fibrous debris found in the sugar cane juice or sucrose from the aforementioned cane juice extractor. The separator tank  20  also has a sediment removal trap and port  20   c , and an outlet. The separator tank  20  has a vertically disposed weir for filtering floating, particulate matter or debris in the sucrose. The sediment removal trap and port  20   c  has a valve  54  for capturing any debris settling from the sucrose. The outlet is coupled to a portion of the conduit system  50 , and one of the pumps  52  for moving the juice from the separator tank  20 . 
         [0030]    The similar portions of each of the tanks ( 20 - 46 ), such as the sediment removal trap and port  22   a ,  24   b ,  26   a ,  28   b ,  30   c ,  34   b ,  36   c ,  40   b ,  42  and valves  54  all function with the same purpose, to capture debris settling from the sucrose or massecuite, and after all of the sugar processing is completed, the valves  54  are opened to flush the sediment out of each tank, Likewise, each tank has an outlet coupling the tank to conduit system  50 , and may include a pump  52 . The conduit system  50  portion coupled to an outlet of one tank, will direct the sucrose or massecuite to an inlet of the successive tank. All of the pumps  52  and valves  54  act in accordance with instructional signals from an actuator  6   a , since the operation of the pumps  52  and valves  54  are included in the loads  6   b.    
         [0031]    The pre-heater tank  22  has a sediment removal trap and port  22   a  and a heater. The clarifier tank  24  has a sediment removal trap and port  24   b , and a motor  24   a  coupled to an agitator (not shown) for agitation of the pre-heated sucrose, causing a mixing operation of a polymer introduced in the clarifier tank  24 . The holding tank  26  maintains the clarified sucrose at the pre-heated temperature via a heater, Upon activation from the programmable logic controller  4 , the clarified sucrose is pumped into the first boiler  28 . The first boiler  28  has a heater for raising the temperature of clarified sucrose to a water boiling point, under pressure. The first boiler  28  has a vacuum pump  28   a  for exhausting the water vapor expelled from the boiling operation. The vacuum pump  28   a  is under the control of the programmable logic controller  4  via the actuator  6   a  as one of the loads  6   b . Likewise, the second boiler  34  and the third boiler  40  have the corresponding parts and functions the second boiler has vacuum pump  34   a ; the third boiler  40  has vacuum pump  40   a . Also included are the operations of the similar loads  61 ) in the second boiler  34  and the third boiler  40 . 
         [0032]    Regarding the first centrifuge  32 , the second centrifuge  38 , and the third centrifuge  44 , each are one of the loads  6   b  under actuation by instructional signals from the programmable logic controller  4  via an actuator  6   a . Similarly, the crystallizer tank  30 , the second crystallizer  36 , and the third crystallizer  42  function in accordance with the same mode of operation. The crystallizer tank  30  has a motor  30   a  and a stirrer  30   b . The stirrer  30   b  is driven by the motor  30   a  to stir the massecuite. The motor  30   a  is one of the loads  6   b  under actuation by instructional signals from the programmable logic controller  4  via an actuator  6   a . Furthermore, the second crystallizer  36  has a motor  36   a , and a stirrer  36   b . The stirrer  36   b  is driven by the motor  36   a  to stir the massecuite. The motor  36   a  is one of the loads  6   b  under actuation by instructional signals from the programmable logic controller  4  via actuator  6   a . In addition, the third crystallizer  42  has a motor  42   a  and a stirrer  42   b . The stirrer  42   b  is driven by the motor  42   a  to stir the massecuite. The motor  42   a  is one of the loads  6   b  under actuation by instructional signals from the programmable logic controller  4  via an actuator  6   a.    
         [0033]    Under the instructions of the output  4   c  of the programmable logic controller  4 , the operational process follows a flow provided by the system  10 . The flow process basically follows a sequence of functions described above. Thus, the portable sugar mill saves the cost of transporting the juice to stationary sugar mills, and produces a fresher product. 
         [0034]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.