Abstract:
A mobile field harvesting process for harvesting and further processing sugar-containing crops, such as sweet sorghum, includes cutting the crop, chopping the crop, and reducing the crop to the crop&#39;s separated juice and solids in the field. Separation is carried out using a chopper and a juicer. The juicer may be a screw press. The juice may be stored and fermented on the farm, followed by distillation by a mobile distillation process to separate the alcohol from the stillage.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a system and method of harvesting and processing sugar-containing crops such as sweet sorghum. More particularly the present invention relates to a mobile harvester for cutting and processing sweet sorghum in the field to yield its juices, and then to further process the juice via fermentation and distillation to produce ethanol. 
         [0003]    2. Background 
         [0004]    Traditionally, sweet sorghum has been harvested for sorghum syrup production by either cutting and handling the stalks by hand, or by chopping the stalks and blowing the chop into a forage wagon; in either case, the resulting plant matter is carried to a central processing station for the extraction of the juices, cooking and reduction of the juices to sorghum syrup. 
         [0005]    The former method requires a large expenditure of manual labor and is typically used in small, such as family sized operations. The juice from the stalks is often squeezed using a single-roller press powered by a horse, mule, or lawn tractor. 
         [0006]    The method of chopping the stalks in the field like ensilage is less labor intensive than the previously mentioned method and larger crops may be harvested and processed this way. The drawbacks of this method, however, include: an enormous amount of crop must be transported out of the field to a central processing location, and the resultant organic matter must then be either returned to the field or otherwise disposed of. 
         [0007]    Another former system for processing sweet sorghum focused on the use of a roller press incorporating multiple rollers. However, roller presses alone may be an inefficient means to extract juice from a sugar-producing crop. 
         [0008]    Energy is a matter of concern to the country, and will continue to be for some time. Air pollution has improved over the past several decades, but still remains an issue in parts of this country, as well. A recognized partial solution to both the energy and pollution problems is ethanol. Sweet sorghum juice, due to its high sugar content, is an ideal raw material for the production of ethanol. Sweet sorghum has the potential to produce over twice the ethanol per acre as corn, the most common raw material used for ethanol production, today, at significantly less cost. As it stands presently, a more efficient method of harvesting the sorghum crop must be employed to make the use of this crop for ethanol production feasible. 
         [0009]    There is, therefore, a need for a low-labor, efficient process for harvesting and field processing sweet sorghum and extracting the juices for further processing at or near the fields of each producer. 
       SUMMARY 
       [0010]    A purpose of this invention is to provide a system and process for field harvesting and processing sweet sorghum crops and extracting the juices for further processing. Another purpose of this invention is to provide a process for fermenting sugar rich substances such as sweet sorghum juice, ultimately for its ethanol. Still another purpose is to provide a portable process for distilling the ethanol from the fermented juice, also referred to herein as wine. 
         [0011]    In general, a field harvesting process for a sugar-producing crop, such as sweet sorghum, is initiated by cutting the stalks of the sugar-producing crop close to the ground in the field and then feeding the stalks to a mobile chopper assembly adapted to chop the stalks of the sugar-containing crop into segments in a field. The segments may have a length less than six inches in length, and preferably, less than one and a half inches in length. The segments are then fed into a mobile juicer coupled to the mobile chopper assembly. The segments have juice encapsulated within fibers. The mobile juicer may extract the juices from the fibers of the segments of the sugar-containing crop in the field. The juices may then be captured by a mobile container adjacent to the mobile juicer for collecting the extracted juices from the mobile juicer in the field. The juice may be pumped or gravity-fed into a storage unit that is also preferably in the field. 
         [0012]    The present disclosure also describes a fermentation process, which takes place within the storage units in a matter of days, and a portable distillation process to recover the ethanol from the resultant wine and to concentrate this ethanol to a suitable concentration for use as fuel ethanol. It should be understood that tanks for storage and fermentation may take many forms. For example, stationary, rigid tanks and/or portable bladders may be used. In either case, a vent for permitting the release of Carbon Dioxide (CO 2 ) gas may be used during the fermentation process. 
         [0013]    A portable distillation process, for example, mounted on a “low-boy” type truck or semi-trailer, may be used to concentrate the ethanol to a fuel level. The distillation process may use fossil fuel(s) for the heat required, but an aspect of the present disclosure is to gasify the solid crop material or bagasse for the heat needed for distillation. A distillation process may comprise a heating unit in which the fermented juices (wine) are heated so the alcohol will evaporate at about 180° F.; a condensing unit in which the alcohol is cooled so it condenses; and a molecular sieve unit in which distilled alcohol is concentrated to fuel grade. 
         [0014]    The novel features which are believed to be characteristic of this invention, both as to its organization and method of operation together with further objectives and advantages thereto, will be better understood from the following description considered in connection with accompanying drawings in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood however, that the drawings are for the purpose of illustration and description only and not intended as a definition of the limits of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more implementations described herein and, together with the description, explain these implementations. The drawings are not intended to be drawn to scale, and certain features and certain views of the figures may be shown exaggerated, to scale or in schematic in the interest of clarity and conciseness. Not every component may be labeled in every drawing. Like reference numerals in the figures may represent and refer to the same or similar element or function. In the drawings: 
           [0016]      FIG. 1  depicts a partial cross-section side view of an exemplary field harvester. 
           [0017]      FIG. 2  depicts a top view of the exemplary field harvester of  FIG. 1 . 
           [0018]      FIG. 3  depicts a partial cross-sectional diagram of an exemplary mobile juicer implemented as a conically shaped screw press in accordance with the present disclosure. 
           [0019]      FIG. 4  depicts a diagrammatic, partial cross-section of another exemplary mobile juicer implemented as a cylindrical screw press in accordance with the present disclosure. 
           [0020]      FIG. 5  depicts a partial cross-sectional side view sketch of another embodiment of an exemplary field harvester having multiple stages of juicers in accordance with the present disclosure. 
           [0021]      FIG. 6  depicts a front view of exemplary segmented roller pairs in accordance with the present disclosure. 
           [0022]      FIG. 7  depicts a cross-sectional view of a segmented roller and a roller drive shaft in accordance with the present disclosure. 
           [0023]      FIG. 8  depicts an exemplary self-propelled field harvester in accordance with the present disclosure. 
           [0024]      FIG. 9  depicts a flow chart of an exemplary mobile distillation process in accordance with the present disclosure. 
           [0025]      FIG. 10  depicts a schematic of an exemplary mobile distillation process in accordance with the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by anyone of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). 
         [0027]    In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the inventive concept. This description should be read to include one or more and the singular also includes the plural unless it is obvious that it is meant otherwise. 
         [0028]    Further, use of the term “plurality” is meant to convey “more than one” unless expressly stated to the contrary. 
         [0029]    As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
         [0030]    Referring now to the drawings,  FIGS. 1 and 2  depict an exemplary mobile field harvester  100  in accordance with the present invention. In particular,  FIG. 1  is a partial cross-sectional side view of the exemplary field harvester  100 .  FIG. 2  is a top view of the exemplary field harvester  100  of  FIG. 1 . In one embodiment, the field harvester  100  is depicted as a pull-behind unit with at least two wheels  101  powered through a power take off (not shown); however it should be understood that the field harvester  100  may have any number of wheels and/or tracks and may be powered in any manner and/or may be a self-contained vehicle unit such as a combine. The mobile field harvester  100  may be used for any sugar-containing crop, for example, sweet sorghum, switch grass, and/or sugar cane. 
         [0031]    In general, the exemplary field harvester  100  may comprise a mobile chopper assembly  104 , a mobile juicer  106 , and a mobile container  108  for collecting the juices. In one embodiment, the field harvester  100  may also comprise a mobile frame  110  which may support a crop cutter assembly  112 , a crop mover assembly  114 , a chopper feeding unit  116 , the chopper assembly  104 , the juicer  106 , and the container  108 . 
         [0032]    More specifically, the frame  110  may have a front end  118  and a back end  120 , as illustrated in  FIG. 2 . The crop cutter assembly  112  may have at least one moveable cutter blade  113  for separating the sugar-containing crop from its roots. The at least one crop cutter blade  113  may be rotatable, for example, the at least one crop cutter blade may be attached to at least one cutter rotor  121 . The crop cutter assembly  112  may be operatively attached to the front end  118  of the frame  110  and sized to cut one or two rows of the sugar-containing crop, as illustrated in  FIG. 2 , or may be sized appropriately to cut one or more rows based on the planting scheme of the sugar-containing crop. For example, the crop cutter assembly  112  may cut a dozen rows or more in one pass of the field harvester  100 . 
         [0033]    The crop mover assembly  114  may grab and move the sugar-containing crop from the crop cutter assembly  112  to, for example, the chopper feeding unit  116 . The rate of movement may be controllable, for instance, mechanically or by electronic control. In the example illustrated in  FIGS. 1 and 2 , the crop mover assembly  114  comprises two gathering screws  122  and at least one support belt  124 . The support belt  124  may assist the gathering screws  122 . For example, the support belt  124  may assist in rotating the stalks of the sugar-containing crop. The support belt  124  may be run at a rate of speed faster than the ground speed of the field harvester  100 . For example, the support belt  124  may run at four feet per second while the field harvester  100  may run at three feet per second, thus rotating the stalks. Of course, it should be understood that the crop mover assembly  114  may contain any variety of crop moving devices, and may be scaled to the number of crop rows being harvested in one pass by the mobile field harvester  100 . For example, the crop mover assembly  114  may comprise one or more conveyor belts or pneumatic conveyors. 
         [0034]      FIG. 1  illustrates an exemplary embodiment of the chopper feeding unit  116 . The chopper feeding unit  116  may have an inlet for receiving the sugar-containing crop from the crop cutter assembly  112 , and an outlet to discharge the sugar-containing crop to the chopper assembly  104 , for example. In one example, the stalks of the sugar-containing crop are rotated toward the chopper feeding unit  116 , for instance, by the support belt  124  in the crop mover assembly  114 . The chopper feeding unit  116  may be designed to grip and move the sugar-containing crop into the inlet of the chopper assembly  104 . The rate of movement may be controllable, for instance, mechanically or by electronic control. In this example, the chopper feeding unit  116  is comprised of two nip rollers  126  which channel the sugar-containing crop to the chopper assembly  104 . The nip rollers  126  may have one or more protrusions  128  to help grip and move the sugar-containing crop. In one aspect of the invention, the chopper feeding unit  116  may be comprised of multiple rollers, or at least two conveyors adapted to move the sugar-containing crop between the at least two conveyors. 
         [0035]    The chopper assembly  104  is adapted to chop the sugar-containing crop in the mobile field harvester  100  while in the field. Typically, the chopper assembly  104  may have an inlet for receiving the sugar-containing crop and an outlet for discharging chopped segments of the sugar-containing crop. In one aspect of the invention, the chopper assembly  104  may comprise at least one chopper blade  138  and a chopper anvil  140 . The chopper anvil  140  may be manually adjustable, or automatically self-adjustable to allow for various diameters of stalks of the sugar-containing crop. In one example, the at least one chopper blade  138  is moveable in a rotary fashion to chop the sugar containing crop into segments. The at least one chopper blade  138  may be attached to, or part of, chopper rotor  144 . In one example, the chopper feeding unit  116 , such as nip rolls  126 , may force the stalk of the sugar-containing crop into the chopper assembly  104 , where the stalk is fractured between the chopper blade  138  attached to the chopper rotor  144  and the anvil  140 . The rotation of the chopper rotor  144  may carry the resulting segment of stalk toward the outlet of the chopper assembly  104 . 
         [0036]    In one example, additional chopper blades  138  and/or additional chopper assemblies  104  may be used to chop the stalks into segments. The stalks may be segmented into any size, however, for efficiency the chopper assembly  104  may be adapted to segment the stalks into pieces less than six inches in length, and preferably, less than one and a half inches in length. In one example, the chopper assembly  104  segments the stalks into segments from one (1) to one and a half (1.5) inches in length. The chopper assembly  104  may chop the stalks into smaller segments by increasing the speed of the at least one chopper blade  138 , for example. 
         [0037]    The mobile juicer  106  may receive the segments of the stalks of the sugar-containing crop and extract juices from the segments, and may discharge the extracted juices to the container  108 . The juicer may be driven by a reversible drive  148 , for example. In one embodiment, the mobile juicer  106  may be a screw press  150  as depicted in  FIGS. 1 ,  2 , and  3 .  FIG. 3  is a depiction of a partial cross-section of the exemplary screw press  150  in accordance with the present disclosure. In this example, the screw press  150  is a conical shaped screw press  150   a , having a first end diameter at an inlet that is larger than a second end diameter at an outlet. In other words, the screw press  150  may have an inlet for receiving the chopped segments of the sugar-containing crop from the chopper assembly  104  in the first end of the screw press  150 . 
         [0038]    The screw press  150  may include a screw  152 , such as conical screw  152   a , having a rotatably drivable internal shaft  154 , inside a housing  156 , such as conical housing  156   a . The screw  152  may be rotatable by the shaft  154  inside the housing  156  such that the segments of the sugar-containing crop are moved and compressed from the first end to the second end of the screw press  150  to extract the juice. The screw  152  may have variable pitch between the first end and second end such that the pitch is smaller toward the second end of the screw  152 . In one example, the shaft  154  may be supported by a bearing  158 , such as nose bearing  158   a . The housing  156  may be fitted to the screw  152  to prevent the segments from escaping when moved and compressed by the screw  152  between the first end and the second end of the screw press  150 . The conical shape of conical screw  152   a  and conical housing  156   a  may allow for adjustment of a gap between the screw  152  and the housing  156 . For example, in cases of wear of the screw  152   a  and/or housing  156   a , the conical screw  152   a  may be moved axially along the shaft  154  toward the smaller second diameter of the housing  156   a , thus decreasing the gap between the screw  152   a  and the housing  156   a.    
         [0039]    The housing  156  may be perforated such that the housing  156  is permeable by the extracted juice, while containing the fibrous material of the segments of the sugar-containing crop between the first end and the second end of the screw press  150  in the housing  156 . In one example, the housing perforations are slanted bores  160  running through the housing  156  and angled in a direction away from the movement of the segments through the screw press  150 , also referred to herein as “back slant.” The back slant of the bores  160  may reduce clogging of the bores  160  by fibrous material of the segments of the sugar-containing crop. 
         [0040]    The screw press  150  may have an outlet  162  on the second end of the screw press  150  for discharging the chopped and squeezed fibrous material of the segments, also referred to herein as “bagasse.” In one embodiment, the pressure of the screw press  150  on the segments of the sugar-containing crop may be adjustable, for example, by utilizing an adjustable choke  164 . The position of the choke  164  relative to the housing  156  may be adjusted to narrow or increase the outlet  162  such that the back-up of the fibrous material of the segments between the screw  152  and the choke  164  causes more pressure to be applied to the segments. 
         [0041]    In one embodiment, the fibrous material of the segments (the bagasse) may be discharged from the outlet  162  to a reversible trash screw  170 . The trash screw  170  may discharge the fibrous material to the field or may discharge the fibrous material to a storage unit (not shown). Of course, other types of movers may be used to convey the fibrous material away from the outlet  162 , for example, one or more mechanical or pneumatic conveyors. 
         [0042]    In one embodiment, the field harvester  100  may also comprise a pump to pump the juice from the container  108 . The juice may be pumped to a juice storage tank. For example, the juice storage tank may be a pull-behind mobile tank pulled by, or with, the field harvester  100 . In one example, the juice storage tank is a separate mobile tank not attached to the field harvester  100 . In another example, the juice storage tank may be immobile. 
         [0043]      FIG. 4  depicts a cross-sectional sketch of an exemplary screw press  150   b  in accordance with the present disclosure. In one embodiment, the screw press  150   b  is cylindrical in shape, including the screw  152   b  and housing  156   b , with the first end diameter and the second end diameter being approximately the same size. In the example of  FIG. 4 , the screw  152   b  is of variable pitch between the first end and second end such that the pitch is smaller toward the second end of the screw  152   b . The screw  152   b  has a plurality of flights that define a helical passage from the first end to the second end. Because the screw  152   b  has a variable pitch, the distance between adjacent flights decreases towards the second end. Because the volume between the flights is dependent upon the distance between the flights, the volume between the flights decreases towards the second end. Thus, as the segments are conveyed from the first end to the second end, the volume of the segments is reduced thereby forcing the juice out of the segments. 
         [0044]    The internal shaft  154  may be supported by end bearing  158   b  and driven by the reversible drive  148 . The reversible drive  148  may allow the rotation of the screw  152  be reversed, for example, to relieve pressure in the screw press  150 . 
         [0045]    In one embodiment, the mobile field harvester  100  may comprise additional juicing components. For example,  FIG. 5  depicts a partial cross-sectional side view sketch of exemplary field harvester  100   a  in accordance with the present disclosure in which the field harvester  100   a  further comprises a roller press assembly  200  for extracting juice from the sugar-containing crop. The roller press assembly  200  may be located before the chopper assembly  104 . The roller press assembly  200  may receive the sugar-containing crop via an inlet and discharge the pressed crop via an outlet. The roller press assembly  200  may comprise one or more roller sets  210 . In one example, the roller sets  210  may comprise one or more of a plurality of segmented roller pairs  212 , each roller pair  212  having a first segmented roller  216  and a second segmented roller  218  aligned with one another such that a gap is created between the outer diameters of the first and second segmented roller  216 ,  218 . The sugar-containing crop may pass in the gap between the segmented rollers in the roller pairs in succession, thus squeezing juice from the sugar-containing crop. The extracted juice may be captured by the container  108 . 
         [0046]      FIG. 6  depicts a front view of exemplary segmented roller pairs  212  in accordance with the present disclosure. The segmented roller pairs  212  may be adapted to allow for pressure to be exerted on different diameter stalks of the sugar-containing crop. For example, if stalks that are of a wider diameter than the size of the gap between the segmented rollers  216  and  218 , then one or both of the segmented rollers  216  and  218  may move, widening the gap and allowing the thicker stalks to pass through while maintaining pressure on the stalks. 
         [0047]    In one embodiment, the segmented rollers  216 ,  218  are self-adjustable. For example,  FIG. 7  depicts a cross-sectional side view of a self-adjustable segmented roller  216  and a roller drive shaft  220  in accordance with the present disclosure. In this example, between the internal diameter of the segmented roller  216  and the roller drive shaft  220 , there may be a layer of compressible material  222 . In this way, if a stalk of the sugar-containing crop that has a larger diameter than the gap between the segmented rollers  216 ,  218  goes between the segmented rollers  216 ,  218 , the compressible material  222  allows the segmented roller  216  to move slightly, that is move by the amount of the compression of the compressible material  222 . Then the compressible material  222  may return to its previous uncompressed dimension. One example of the compressible material  222  is high durometer rubber. In one example, the compressible material  222  may be chosen for properties that allow for compression based on a required pressure, so as to maintain a minimum pressure on the stalks of the sugar-containing crop to extract juice. 
         [0048]      FIG. 8  depicts one embodiment of an exemplary self-propelled field harvester  100   b  which is similar in construction to the harvester  100   a  with the exception that the harvester  100   b  is self-propelled. The self-propelled field harvester  100   b  may be powered by an engine  360 , such as a diesel engine, rather than drawn by a tractor, for example. The harvester  100   b  may be operated from a cab  365 . The crop cutter assembly  112  and crop mover assembly  114  may be carried on the front of the field harvester  100   b  where the crop is sheared from the ground and transferred to the mobile juicer  106 , such as roller press assembly  200  and/or screw press  150 . In one embodiment the solids (i.e. the bagasse) leaving the screw press  150  may be made into pellets in a rotary ring pelletizing process unit  350  and transported to storage. The pellets may be used for fuel for alcohol distillation, for livestock feed or for other purposes. Of course, it should be understood that the solids may instead be converted into other, marketable products. 
         [0049]    A pH adjustment of the juices is carried out, if necessary before or as the juices are pumped to the storage tank  370 . A tank for acid  380  for adjusting the pH of the juice to about 4.5-4.8 may be carried in front of a water tank  385 . In this example, the extracted juices may pass to an optional pH adjustment unit  335  where the pH may be measured and adjusted to about 4.5-4.8 to inhibit bacterial action. If the final product is to be lactic acid or some other products, this step may be unnecessary. The juices may then be stored for fermentation and subsequent distillation. Yeast may be introduced on board the harvester  100   b . The juices may be filtered in filtering unit  390 . 
         [0050]    After the sweet sorghum crop has been processed into its juices in the field harvester  100 , the juices may be further processed into a useable and saleable product. Other aspects to the present invention include further storage and processing including fermentation and distillation. 
         [0051]      FIG. 9  depicts an exemplary process  600  in accordance with the present invention. In one embodiment, the juices from the field harvester  100  may be transferred into storage/fermentation tanks  605 . During transfer from the field harvester  100 , selected yeasts may be added. The fermentation tanks  605  may take many forms, for example, rigid, stationary tanks and/or portable, fiber elastic bladders. The fermentation process typically lasts for a few days. Throughout fermentation, CO 2  is produced. Irrespective of the form of the storage/fermentation tanks  605 , the fermentation tanks  605  typically have a vent  610  for venting the CO 2  produced by the yeast during fermentation. The CO 2  may be captured for sale. 
         [0052]    The fermented juices (wine) laden with ethanol may be transported or transferred from the storage/fermentation tanks  605  under gravity or with a wine pump  615  into a wine tank  620 . From the wine tank  620 , the wine may be transported under gravity or by a distillation pump  625  into a distillation boiler/column  630 . In the distillation column  630 , the alcohol may be separated from the remainder of the wine, or stillage. The resulting low-grade alcohol may be further cooled in a heat exchanger  635  used to preheat the wine before being further refined in a molecular sieve stripping unit  665 . This final product fuel ethanol may then be loaded into a tank for storage or transport. 
         [0053]    Heat for the distillation column may be provided by heating water in a boiler  640 . The fuel  645  for the boiler may be Liquid Propane (LP), or other fossil fuel, or the bagasse (the solids left over after removing the juice from the sugar-producing crop, such as sweet sorghum) may be put through the process of gasification, and the resulting fuel  645  burnt to heat the boiler  640 . The heat from the bagasse burning can also be used in the distillation process. 
         [0054]    Gasification of a carbonaceous material such as bagasse results in a fuel referred to as producer gas. The combustible components are, largely, carbon monoxide (CO) and hydrogen (H 2 ). 
         [0055]    Steam, from the boiler  640 , may first travel to the distillation column  630 . From the distillation column  630 , the condensate may be used in the line from the wine tank  620  to preheat the wine before distillation. A wine tank heat exchanger  650  in the wine tank  620  may impart the heat to the wine. From the wine tank  620 , the condensate may move to a condensate holding tank  670 . The condensate may be finally returned to the boiler through a boiler feed pump  660 . A heat transfer fluid may also be used, instead of steam, to transfer heat for the distillation process. 
         [0056]      FIG. 10  depicts an example of a portable part of the distillation process  600  (also inside the heavy dot-dashed line in  FIG. 9 ). In this case, the distillation column  630 , with its heat exchanger  635 , the boiler  640 , condensate holding tank  670 , the wine tank  620 , the molecular sieve stripping unit  665 , associated pumps  615 ,  625 , the boiler feed pump  660 , and associated controls are carried on a semi-trailer  700 . It should be understood that other combinations are also possible. The semi-trailer  700  may carry the distillation process  600  to the field where the sugar-containing crop is being harvested by the field harvester  100 . 
         [0057]    The above embodiments are the preferred embodiments, but this invention is not limited thereto. Many of the elements of the process mentioned, above, are optional, providing for a large degree of flexibility and pricing. It is, therefore, apparent that many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.