Abstract:
A means to conserve substantial amounts of heat and water, and there by reduce capital and operating costs, by combining salient features of strictly forced convection container cooler or strictly evaporative container cooler in to a hybrid container cooler in which heat removed from cooling the containers is recovered for use, typically in the same processes, upstream of the point of recovery. The recovery and reuse of heat correspondingly reduces water evaporated, which is now conserved. The cooler also features suction of cooling air at close to vapor pressure at cooling and substantially reducing volume of this air that is recycled, and is at a relatively constant temperature.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention is related to a cooler for containers. In particular, the invention relates to a cooler for food product containers, such as bottles and cans. It is further related to conserving heat and water by recovering heat during cooling of these containers and re-using it to heat contents of subsequent containers for a variety of process purposes. These purposes include pathogen reduction, controlled microbial death or growth, or regulation of chemical, bio-chemical, or enzymatic reactions. 
       BACKGROUND OF THE INVENTION 
       [0002]    Containers that have been filled with hot substances, such as food, or heated after being filled, typically must be cooled before distribution and use. One example is an empty container that is filled with a hot product. This hot product pasteurizes or commercially sterilizes the container and the seal when applied. Another example of a container that is heated, then cooled before distribution and use, is a food product container. Often, food products are sterilized or pasteurized to reduce spoilage and to reduce the number of pathogens in the food product. A food product can be treated for pathogen reduction before packaging, or can be filled into a container that then is sealed, and the entire closed container is heated to achieve the desired degree of pathogen reduction. Typically, this degree of pathogen reduction is known as “commercial sterilization.” The food product container then is at elevated temperature and is cooled before distribution and use. Containers of other products, such as animal food, or any product that is heated as a step in processing, also can require cooling. 
         [0003]    Typically, containers of food products leave the pathogen reduction step at a temperature of at least about 150° F. It is possible to cool such containers by allowing them to cool in air to achieve the desired temperature reduction. However, cooling in air, even in a forced air or cooled air stream, is not commercially practical. Such cooling requires not only significant time but also large cooling/storage areas. Also, it is necessary to deal with the heat removed. 
         [0004]    Food product containers typically are cooled by heat exchange with a cooling fluid. Water is a convenient cooling fluid. Various methods and apparatus for cooling containers are known. For example, cooling water can be sprayed on containers to be cooled. Alternatively, the containers can be introduced into a cooling bath to be cooled. Although it is possible to spray cool water onto a container in a once-through process, multiple zones are preferred. 
         [0005]    In a multiple zone system, the cooling fluid and the containers to be cooled move countercurrently, i.e., in opposite directions. Thus, in a first zone, the coolest cooling fluid is used to cool the coolest containers to the target cool temperature. The fluid leaving this first zone is used to cool the warmer containers in the second zone. The pattern continues to the last zone. The last cooling zone is the zone into which the hot containers are introduced. The cooling fluid is the warm cooling fluid, which is raised to its highest temperature in this last zone. 
         [0006]    Multiple zone systems also may have plural processing lines in each zone. For example, two or more processing lines for containers to be cooled may be stacked vertically in a cooler. In this way, cooling fluid from an upper processing line then can impinge upon the containers on a processing line at a lower level of the cooler to cool the lower processing line. Also, a lower line may have an additional cooling fluid source. 
         [0007]    In this zone system, the cooling fluid can be withdrawn from a sump. The sump for the first zone is fed from a cool fluid source, and the sump for each subsequent zone is fed with cooler fluid from the previous cooling zone. The hot fluid from this last cooling step is collected. Typically, this hot fluid is cooled and recycled. 
         [0008]    Often, the hot fluid is cooled by an evaporator-type cooling tower. The cooled fluid then is returned to the first cooling zone. Alternatively, the fluid is cooled by contact in a heat exchanger with a fluid that is circulated in a closed loop between the heat exchanger and a cooling tower. 
         [0009]    In an alternative design, evaporative cooling is incorporated into the cooler itself Cooling fluid, typically water, is evaporated in the cooler itself, then discharged to the atmosphere. Evaporation is effected by a flow of unsaturated air over the cooling fluid surface in the cooler. 
         [0010]    Although both evaporative cooling and cooling by heat exchange, as with a cooling tower, are known, these methods lose or waste both heat and cooling fluid, typically water, to the atmosphere. Therefore, there exists a need for a method for cooling containers that reduces the amount of waste. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    A first embodiment is directed to a method for cooling containers including both evaporative cooling and cooling by heat exchange, wherein cooling fluid is recovered rather than lost to evaporation. 
         [0012]    A second embodiment is directed to a method for cooling containers including cooling vaporized coolant fluid in a condenser to condense the coolant fluid and recover heat and cooling fluid otherwise lost to the atmosphere. 
         [0013]    A third embodiment is directed to a method for cooling containers including tempering air and cooling vaporized coolant fluid through a condenser to condense the coolant fluid and recover heat and cooling fluid otherwise lost to the atmosphere, wherein heat is recovered from condensed coolant and tempered air is returned to the cooler. 
         [0014]    A fourth embodiment is directed to a method for cooling containers wherein the coolant is cooled with fluid and the heat is recovered from that fluid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  shows a single deck cooler of the prior art. 
           [0016]      FIG. 2  shows a single deck evaporative cooler of the prior art. 
           [0017]      FIG. 3  shows an embodiment of a hybrid cooler of the invention. 
           [0018]      FIG. 3A  shows another embodiment of a hybrid cooler of the invention. 
           [0019]      FIG. 3B  shows another embodiment of a hybrid cooler of the invention. 
           [0020]      FIG. 4A  shows one embodiment by which heat from the hybrid cooler is utilized and recovered. 
           [0021]      FIG. 4B  shows an alternative embodiment by which heat from the hybrid cooler is utilized and recovered. 
       
    
    
       [0022]    In the Figures, like numbers are used to illustrate like parts in each drawing figure. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    A first embodiment is directed to a method for cooling containers including cooling vaporized coolant fluid through a condenser to condense the coolant fluid and to recover heat and cooling fluid otherwise lost to the atmosphere. 
         [0024]    A second embodiment is directed to a method for cooling containers including cooling vaporized coolant fluid through a condenser to condense the coolant fluid and recover heat and cooling fluid otherwise lost to the atmosphere, wherein condensed coolant is introduced into zones of the cooler. 
         [0025]    A third embodiment is directed to a method for cooling containers including cooling vaporized coolant fluid through a condenser to condense the coolant fluid and recover heat and cooling fluid otherwise lost to the atmosphere, wherein air carrying the vaporized coolant is recovered and recycled by introduction into zones of the cooler. 
         [0026]    A fourth embodiment is directed to a method for cooling containers wherein the coolant is cooled with fluid and the heat is recovered. The heat thus recovered can be used elsewhere. 
         [0027]    The invention relates to cooling of containers. Containers that have been filled with hot substances, such as food, or heated after being filled, typically must be cooled before distribution and use. One example is an empty container that is filled with a hot product. This hot product pasteurizes, or commercially sterilizes the container and the seal when applied. Another example of a container that is heated, then cooled before distribution and use, is a food product container. Often, food products are sterilized or pasteurized to reduce spoilage and to reduce the number of pathogens in the food product. A food product can be treated for pathogen reduction before packaging, or can be filled into a container that then is sealed, and the entire closed container is heated to achieve the desired degree of pathogen reduction, i.e., commercial sterilization. The food product container then is at elevated temperature and is cooled before distribution and use. Containers of other products, such as animal food, or any product that is heated as a step in processing, also can require cooling. 
         [0028]    A single deck cooler known in the art is illustrated in  FIG. 1 . Containers to be cooled are placed on continuous belt or other conveyance B at point B 1  and are removed from the belt at point B 2  after being cooled. The containers pass through a plurality of cooling zones Z. These zones operate at high temperature at the end at which the containers are introduced, and at low temperature at the end at which the containers are discharged. 
         [0029]    Cooling fluid, typically water, is introduced into each zone at CF. The cooling fluid and the containers move countercurrently, i.e., in opposite directions. Thus, in a first zone, the coolest cooling fluid, at point CF 2 , is used to cool the coolest containers to the target cool temperature. The cooling fluid then is recovered and is introduced into the next zone, typically by allowing the fluid to flow over a weir as illustrated at F. There, the cooling fluid is collected, typically in a sump S, and is used to cool the containers in that zone. The cooling fluid warms as it moves through zones Z as it cools the containers passing countercurrently through the zones. 
         [0030]    In this known system, hot cooling fluid is recovered at point CF 1  from the last zone, i.e., the zone into which the hot containers are introduced, and circulated to heat exchanger H. The cooling fluid is cooled in heat exchanger H and returned to the beginning of the cooling fluid flow at point CF 2 . The heat from the cooling fluid is exchanged to a second fluid circulating in a closed loop between heat exchanger H, where this second fluid is heated, and cooling tower T, where the second fluid is cooled with cooling water, as illustrated. This cooling water evaporates to provide the cooling effect, and is lost to the atmosphere. 
         [0031]      FIG. 2  illustrates a known single deck evaporative cooler. As in  FIG. 1 , containers to be cooled are placed on continuous belt or other conveyance B at point B 1  and are removed from the belt after being cooled at point B 2 . The containers pass through a plurality of cooling zones Z. These zones operate at high temperature at the end at which the containers are introduced, and at low temperature at the end at which the containers are discharged. 
         [0032]    Cooling fluid, typically water, is introduced into each zone at CF. The cooling fluid and the containers move countercurrently, as in  FIG. 1 . The cooling fluid then is recovered and is introduced into the next zone, typically by allowing the fluid to flow over a weir, as illustrated at F. There, the cooling fluid is collected, typically in a sump S, and is used to cool the containers in that zone. The cooling fluid warms as it moves through zones Z as it cools the containers passing countercurrently through the zones. 
         [0033]    In this known system, the cooling fluid is not re-circulated through the cooling tower. Rather, cooling is obtained by evaporation of the cooling fluid into vapor collection hood V. As shown in  FIG. 2 , one vapor collection hood V collects the evaporated cooling fluid from all zones Z. However, it is possible to have plural vapor collection hoods that collect vapor from a single zone of from multiple zones. Thus, there can be between one vapor collection hood for the entire process and one vapor collection hood per zone. To ensure that a sufficient quantity of vapor is removed to cool the cooling fluid, blower VB is used to remove vapors from vapor collection hood V. There are as many blowers as there are vapor collection hoods. Blower VB sucks air through the cooling zones to evaporate cooling fluid. These vapors and the air are exhausted to the atmosphere at V 1 . Thus, cooling fluid is lost to the atmosphere. The entirety of the heat load is rejected by evaporation of the cooling fluid. 
         [0034]    Each of these systems is wasteful. The conventional system requires a cooling tower and wastes heat in the form of evaporated fluid in the cooling tower. The evaporative system is wasteful as it requires evaporation of cooling fluid and a significant flow of air. 
         [0035]    The inventor has discovered that it is possible to recover heat removed from the cooled containers in a hybrid system. The heat thus recovered can be used in another process or location. In one embodiment, this recovered heat is used to heat the contents of subsequent containers for pathogen reduction. 
         [0036]    The inventor has discovered that it is possible to obtain the advantages of each type of conventional cooler of the types illustrated in  FIGS. 1 and 2  in a single hybrid cooler in which it is further economical to recover heat lost to the atmosphere in conventional coolers. This additional synergy in recovering heat typically lost to the atmosphere is particularly valuable. The heat can be used for any purpose, including in particular to heat (typically for pathogen reduction) the product that later is cooled in the cooler. In addition, the water lost to evaporation in conventional practices also is conserved. 
         [0037]    One embodiment of the hybrid cooler system of the invention is illustrated in  FIG. 3 . As illustrated therein, containers to be cooled are placed on belt or other conveyance B at point B 1  and are removed from the belt after being cooled at point B 2 . The containers pass through a plurality of cooling zones Z. These zones operate at high temperature at the end at which the containers are introduced, and at low temperature at the end at which the containers are discharged. 
         [0038]    Cooling fluid, typically water, is introduced into each zone at CF. The cooling fluid and the containers move countercurrently, i.e., in opposite directions. Thus, in a first zone, the coolest cooling fluid, at point CF 2 , is used to cool the coolest containers to the target cool temperature. The cooling fluid then in recovered and is introduced into the next zone, as illustrated at F. Typically, the fluid is allowed to flow over a weir, as illustrated in  FIG. 3 . In this next zone, the cooling fluid is collected, typically in a sump S, and is used to cool the containers in that zone. The cooling fluid warms as it moves through zones Z as it cools the containers passing countercurrently through the zones. 
         [0039]    In this embodiment of the invention, hot cooling fluid CF 1  is removed from the last sump S and is processed through heat exchanger H, wherein it is cooled. The cooled cooling fluid CF 2  is returned to the first sump for use in the lowest temperature zone. 
         [0040]    Also, in this embodiment of the hybrid system, cooling fluid is evaporated and removed from the system together with air at vapor collection hood V. One such vapor collection hood that serves all zones F is illustrated in  FIG. 3 . Alternative embodiments for vapor collection hoods are illustrated in  FIGS. 3A and 3B , which illustrate, respectively, two vapor collection hoods for the entire system and 1 vapor collection hood for each zone. The number of vapor collection hoods ranges from 1 to the number of zones Z. For convenience, the embodiments are described in detail only with regard to a single vapor collection hood V and blower VB (described below). The air and evaporated cooling fluid V 1  are sucked out of the cooler by blower VB and introduced to condenser C. 
         [0041]    Heat is recovered from both condenser C and heat exchanger H. The heated streams recovered from these heat exchangers are used in other processes requiring heated streams for heat exchange to heat still other fluids. In the embodiment illustrated in  FIG. 3 , these heat streams are combined before being sent to, for example, a hot water storage facility. 
         [0042]    In accordance with the embodiment illustrated in  FIG. 3 , the air and evaporated cooling fluid V 1  evacuated from the cooler through vapor collection hood V and blower VB are introduced to condenser C. Stream V 1  is condensed in condenser C and the air is cooled. Cool or tempered air stream Al is returned to cooling zones Z, as illustrated at points A. This air recycle feature, which is not available on conventional evaporative coolers, saves energy by providing the ability to recycle the air flow and to provide a constant-temperature air source to the cooler. In a conventional evaporative cooler, this air is evacuated, there being no capacity to cool it, and fresh air always is used. 
         [0043]    Evaporated cooling fluid from stream V 1  is condensed in condenser C and taken as condensate stream C 3  to hot fluid collection and re-use C 1 . As noted above, C 1  can be a combined stream from all the hot fluid sources, or these streams can be used individually. 
         [0044]    Evaporated cooling fluid is condensed and air sucked out of the cooler is cooled in condenser C by exchange of heat with cooling fluid stream C 2 . This cooling fluid typically is water, but can be any suitable heat exchange fluid. Stream C 2  is heated in condenser C and exits the condenser as hot fluid stream C 4 . Stream C 4  is removed to hot fluid collection point C 1 , where it can but need not be combined with other hot fluid streams to be collected for use in other processes. 
         [0045]    Cooling fluid stream C 2  also is introduced to heat exchanger H to cool the recirculating cooling fluid used to cool containers in the cooler. After heat exchange, hot fluid stream C 5  is set to hot fluid collection point C 1  or for use as a heat source in another process. 
         [0046]    Thus, in this embodiment of the invention, heat that otherwise would be lost is recovered in streams C 3 , C 4 , and C 5  and used in other processes or collected at C 1  for use in other processes. One embodiment of this use includes heating the fluid in the containers for pathogen control. These containers then are cooled in the hybrid cooler. This embodiment also encompasses recovery and cooling or tempering of air typically sucked through the cooler and exhausted. Not only is the cooling air recycled, but also the air is made available to the cooling process at a relatively constant temperature. This constancy affords the opportunity to more evenly control the system. 
         [0047]    In an embodiment of the invention, blower VB is designed to have a suction pressure approximately equal to the vapor pressure of coolant at temperature. In this embodiment, it is advantageous to have a vapor collection hood V for plural zones Z, as illustrated in  FIG. 3A .  FIG. 3A  illustrates one vapor collection hood V per two zones Z. It is even more advantageous and preferred to have one blower VB and vapor collection hood V for each zone Z, as is illustrated in  FIG. 3B . In this way, the suction pressure can be closely matched to the vapor pressure of the liquid. 
         [0048]    Matching the blower suction pressure to the vapor pressure of the coolant creates efficiency not present when only one vapor collection hood is present. Matching the blower suction pressure to the vapor pressure of the coolant minimizes the volume of air and coolant vapors sucked by blower VB. Thus, blower size, the sizes of both the suction and discharge ducts, and the power consumed during operation all are smaller when the blower is sized for the suction temperatures and pressures. 
         [0049]    In accordance with one embodiment of the invention, the quantity of air and evaporated cooling fluid now is controlled and made sufficient to compensate for diminished cooling capacity on hot and humid days. Although it typically is possible to maintain the temperature difference between the hot and cool cooling fluid streams CF 1  and CF 2 , the ability of the cooling fluid to cool the containers is reduced on hot days, and particularly on hot and humid days. Therefore, in this embodiment, the quantity of air and evaporated cooling fluid is adjusted to compensate for this diminished capacity. 
         [0050]    Each of drawing  FIGS. 1-3B  illustrates coolers having eight (8) zones, and a single deck. There may be more or fewer zones and more or fewer decks in such coolers. Typically, there are between about 4 and about 12 such zones. Typically, there is one deck, but the invention applies equally to coolers having 2 or even 3 decks. 
         [0051]    As illustrated in  FIGS. 4A and 4B , heat absorbed by the cooling fluid can be used to heat the product, or containers of product, as part of pathogen reduction. The heat transferred from the cooling fluid to the product likely is not sufficient to raise the temperature of the product to the temperature required for commercial sterilization. However, the fluid can be used to reduce the amount of heat, from whatever source, required to achieve commercial sterilization. 
         [0052]    As shown schematically in  FIG. 4A , stream C 1  is used in HE 1  to provide heat to product stream P 1 . Product stream P 2  leaves HE 1  warmer than P 1  entered the heat exchanger, and C 10  leaves cooler than C 1 . C 10  then can be returned to the cooler and re-introduced into cold coolant stream CF 2  to make up for at least part of the losses of vaporized coolant fluid, as shown in  FIGS. 3A and 3B . Product P 2  then can be heated to commercial sterilization temperature and packaged. 
         [0053]    An alternative embodiment is illustrated in  FIG. 4B , which illustrates optional heating of C 1  in heat exchanged HE 3  to raise the temperature to be sufficient to commercially sterilize products in containers P 10  on conveyor B 9 . As the containers are moved through heat exchanged HE 1 , warmed fluid C 1  is sprayed onto or otherwise contacted with containers B 10  to heat them. Cooled fluid C 10  can be returned to the cooler at CF 1 , as shown on  FIGS. 3 ,  3 A, and  3 B. Containers then can be moved into optional heater HE 2 , where the temperature of the contents of containers B 10  is raised to commercial sterilization temperature, if necessary. Thus, sterilized bottles B 1  then are moved to the cooler of  FIGS. 3 ,  3 A, and  3 B. 
         [0054]    These embodiments are examples of how heat removed in the hybrid cooler can be captured and returned to the product at a time heat is needed. Other uses for this heat can be identified. 
         [0055]    The skilled practitioner recognizes that, typically, cooling fluid is flowed through the cooler counter-currently to the direction of the conveyance for the containers. However, it is possible to introduce coolant to each zone individually, or to establish a subset of zones through which cooling fluid flows before it is considered spent. It also is possible to pass cooling fluid and containers concurrently through the cooler. The choice of processing scheme is a design consideration left to the skilled practitioner. 
       EXAMPLES 
       [0056]    The following example includes a comparison of a typical cooler of the type illustrated in  FIG. 1  with an embodiment of a hybrid cooler described herein. In each cooler, 20 ounce bottles are cooled at a rate of 1200 bottles per minute in 8 zones. The specific heat capacity of the bottles is 1.04 BTU/lb/° F. The water flow rate for streams is 550 GPM in each zone. The coolant flow rate is 1,800 gpm, and the specific heat capacity of the coolant is 1 BTU/lb/° F. The residence time in each zone is about 2.45 minutes. 
         [0057]    The following tables summarize the temperatures of product into and out of each zone, the temperatures of cooling fluid into and out of each zone, the heat removed in each zone and the retainer flow rate (i.e., the flow ration of stream F). 
         [0000]    
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Conventional Cooler 
               
             
          
           
               
                   
                 Zone 
               
             
          
           
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
                   
               
             
          
           
               
                 Temp. 
                 ° F. 
                 179 
                 155 
                 137 
                 124 
                 115 
                 108 
                 103 
                 99 
               
               
                 of fluid, 
               
               
                 in 
               
               
                 Temp. 
                 ° F. 
                 155 
                 137 
                 124 
                 115 
                 108 
                 103 
                 99 
                 97 
               
               
                 of fluid, 
               
               
                 out 
               
               
                 Heat 
                 kBTU/h 
                 2,395 
                 1,797 
                 1,298 
                 948 
                 679 
                 489 
                 349 
                 230 
               
               
                 Removed 
               
               
                 per zone* 
               
               
                 Temp. 
                 ° F. 
                 99 
                 96 
                 94 
                 93 
                 92 
                 91 
                 91 
                 90 
               
               
                 of coolant, 
               
               
                 in 
               
               
                 Temp. 
                 ° F. 
                 108 
                 103 
                 99 
                 96 
                 94 
                 93 
                 92 
                 91 
               
               
                 of coolant, 
               
               
                 out 
               
               
                 Retainer 
                   
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
               
               
                 flow rate 
               
               
                 Heat carried 
                 kBTU/h 
                 2,395 
                 1,797 
                 1,297 
                 948 
                 679 
                 489 
                 349 
                 230 
               
               
                 By coolant 
               
               
                   
               
               
                 *Total Heat Removed per zone varies, total heat removed in cooler is 7,955 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Hybrid Cooler 
               
             
          
           
               
                   
                 Zone 
               
             
          
           
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
                   
               
             
          
           
               
                 Temp. 
                 ° F. 
                 179 
                 159 
                 143 
                 130 
                 130 
                 112 
                 106 
                 101 
               
               
                 of fluid, 
               
               
                 in 
               
               
                 Temp. 
                 ° F. 
                 159 
                 143 
                 130 
                 120 
                 112 
                 106 
                 101 
                 97 
               
               
                 of fluid, 
               
               
                 out 
               
               
                 Heat 
                 kBTU/h 
                 1,996 
                 1,597 
                 1,297 
                 998 
                 798 
                 598 
                 499 
                 399 
               
               
                 Removed 
               
               
                 per zone* 
               
               
                 Temp. 
                 ° F. 
                 118 
                 110 
                 103 
                 99 
                 95 
                 94 
                 91 
                 89 
               
               
                 of coolant, 
               
               
                 in 
               
               
                 Temp. 
                 ° F. 
                 125 
                 116 
                 108 
                 103 
                 98 
                 96 
                 93 
                 90 
               
               
                 of coolant, 
               
               
                 out 
               
               
                 Retainer 
                   
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
                 1,800 
               
               
                 flow rate 
               
               
                 Heat carried 
                 kBTU/h 
                 1,996 
                 1,597 
                 1,297 
                 998 
                 798 
                 599 
                 499 
                 399 
               
               
                 By coolant 
               
               
                   
               
               
                 *Total Heat Removed per zone varies, total heat removed in cooler is about 7,785. about 0.15 to 2.5 gpm of water are evaporated from the first to the last zones in this hybrid cooler. 
               
             
          
         
       
     
         [0058]    While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.