Abstract:
A treatment system that treats the interior of one or more tubes of a tube bundle. The system circulates treatment fluid within the tubes being treated. A manifold distributes the treatment fluid among the tubes being treated in the case of treatment of more than one tube where the tubes are to be treated simultaneously. A device is provided that both seals the ends of the tubes being treated and forms a passage by which the treatment fluid is introduced into and removed from the tubes. The treatment system can be a tube cleaning system that removes foreign material from the interior of the tubes.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to the flow of fluid through tubes, including the treatment of the interior of tubes. 
         [0002]    Many types of equipment employ tubes or tube bundles. It is often necessary to introduce a fluid into the tubes and to remove fluid from the tubes, for a variety of purposes. For example, it is often necessary to treat the interior of these tubes. In many instances, foreign matter builds up on the inner surfaces of the tubes, which degrades performance of the equipment, and must be cleaned to remove the foreign matter. 
         [0003]    For example, heat exchangers and other types of condensers, particularly those used in the production of electrical power, develop scale on the interior surfaces of the condenser tubes. This scale impedes heat transfer between the interior of the tubes and the fluid (for example, water or steam) surrounding the tubes, and reduces the efficiency of the power generator. The term “fluid” is used herein to include both gases and liquids. In a typical condenser, for example, the tube bundle is contained with an enclosed condenser box, which affords limited access to the tube bundle. Cleaning the interior walls of the tubes is a challenge, given the difficult access to the interior of the tubes, and the need to accomplish the cleaning as quickly as possible to minimize the down time of the generator. 
         [0004]    The current technology employed to clean the interior surfaces of tubes falls broadly into one of three categories: mechanical tube cleaning, hydro-blasting, and chemical cleaning. Each technique is very well known to those in the industry. 
         [0005]    Mechanical tube cleaning is generally the fastest method for cleaning deposits from the interior surfaces of tubes. There are numerous types of mechanical tube cleaners, the design of which are based on the type of deposit the device will be removing. Mechanical tube cleaning devices can be used to remove very soft to very hard deposits. Examples of hard deposits are calcium, mostly calcium carbonate, manganese, and silica-based deposits. Mechanical tube cleaning involves propelling a tube cleaner, also known as a scraper, through the tube using a fluid under pressure. As water propels the tube cleaner, deposit is removed by the contact points of the device and then remaining deposit is subsequently flushed out by the water. Mechanical cleaning is generally the most common method because it is fast, cost effective, and the more durable tube cleaning devices are able to remove most deposits. The major disadvantage of this method is that some deposits are so difficult that mechanical cleaning is either not effective or less cost effective than other techniques. For example, a very thick calcium carbonate deposit would be very hard to remove with a mechanical tube cleaner. With such a deposit, it is likely necessary to make multiple passes through the tube with different sized scrapers. The process would begin with a smaller diameter scraper, with subsequent passes being made by scrapers with increasingly larger diameters to progressively scrape layers of scale from the inner tube surface. Depending on the size of the deposit, the mechanical process could be impractical in this case. 
         [0006]    Hydro-blasting uses extremely high pressured water to remove deposit from the inner walls of tubes. An operator uses a lance that shoots out high pressured water and manually feeds this lance down each tube. This method can be seen as a substitute to mechanical tube cleaning, but has some significant disadvantages. Generally hydro-blasting takes more time than mechanical tube cleaning and the high pressured water can make this method extremely unsafe for the lance operator. 
         [0007]    Chemical cleaning is preferable on small tube bundles (fewer than about 3,000 tubes of average length, typically between 20 to 50 feet in length), or when larger tube bundles have very serious deposits. Broadly, chemical cleaning involves flushing chemicals through the tubes. The chemical comes into contact with scale, and dissolves it. Typically, the entire condenser tube bundle is filled with the chemical. This system uses a re-circulating pump system that includes an inlet hose that forces the chemical from a reservoir into the bundle, and an outlet hose that evacuates the chemical and returns it to the reservoir. The chemical is re-circulated from the reservoir by the pump until the cleaning operation has been completed. New chemical is supplied to the bundle from a separate reservoir either automatically by a pump or manually. Some systems include a pH gauge that monitors the changing pH of the chemical during the cleaning operation. As the chemical dissolves the deposit, the pH of the chemical changes, typically increasing. When the pH of the chemical rises to a predetermined level, another pump begins supplying chemical from a separate reservoir. Also typically, the predetermined pH level of the system can be set within a range. While this system is effective in removing deposits from the tubes, it is expensive primarily due to the cost of the chemical required to completely fill the tube bundle. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a device for providing fluid access to the interior of a tube, and a system, method and device for circulating fluid through tubes. The system can be used for treating the interior surface of one or more tubes, and utilizes a sealing device of the type provided by the present invention that seals the ends of the tube while permitting the fluid to enter and exit the tube. The system can be used to force a chemical liquid through the tube to remove scale from the interior surfaces of the tube. The system can be used to treat individual tubes or multiple tubes. Entire sections of a tube bundle can be treated. The system provided by the present invention is particularly useful for cleaning scale from the interior of tubes, like those in the tube bundle of a condenser or heat exchanger, using a chemical cleaning fluid. The sealing device can be used to introduce fluid into a tube, and allow for removal of the fluid from the interior of a tube for any purpose, including cleaning or descaling the interior surface walls of the tube. 
         [0009]    The sealing device provided by the present invention includes an inlet for receiving fluid, an outlet, a fluid passage adapted to permit flow of the fluid between the inlet and the outlet, and a seal adapted to prevent flow of the fluid between the sealing device and the interior of the tube. A first sealing device may be mounted within a first end of a tube and a second sealing device may be mounted within a second end of the tube to permit the fluid to pass through the tube. In a preferred embodiment of the invention, the sealing device provides a seal between the device and the tube wall utilizing a sealing material that can be expanded under pressure to force the sealing material against the interior surface of the tube to provide a seal against fluid leaking from the tube, and against foreign matter entering the tube from the exterior of the tube. Preferably, the sealing material is expanded against the inner surface of the tube using a nut and bolt assembly provided with the sealing device that compresses the sealing material. Also preferably, the sealing material is at least one sealing sleeve. In most applications, two sealing sleeves are preferred. 
         [0010]    A treatment system provided by the present invention is used to treat the interior surfaces of at least one tube with a treatment fluid. The treatment system can be used to remove scale from the inner surfaces of tubes by forcing a chemical through the tube. 
         [0011]    The system includes a supply of treatment fluid, a feed that provides treatment fluid from the supply to the tube, a return that recirculates treatment fluid to the supply after it has passed through the tube, and a sealing device of the type provided by the present invention. The sealing device establishes fluid communication between the supply and the interior of the tube. The device includes an inlet and an outlet, a fluid passage adapted to permit flow of the treatment fluid between the inlet and the outlet, and a seal adapted to prevent flow of the fluid between the device and the interior of the tube, and to prevent foreign matter from entering the tube from the exterior of the tube. 
         [0012]    The treatment system can be used to isolate a section comprising multiple tubes to clean more than one tube of the tube bundle while bypassing sections that do not need to be cleaned. In this instance, a sealing device is mounted in the inlet and outlet ends of the tubes being cleaned, and manifolds are provided that are in fluid communication with the inlets and outlets of the tubes being cleaned. As is known in the art, the manifolds distribute the treatment fluid to and from the tubes being treated. 
         [0013]    The system provided by the present invention can be configured in a number of ways to treat a section comprising multiple tubes. For example, a section of six tubes can be treated by configuring the system in a “multiple loop” configuration. In a multiple loop configuration, pairs of tubes are coupled to allow treatment fluid to enter a first tube of the pair, exit the first tube and enter the second tube. The fluid is returned to the system upon exiting the second tube. In this configuration, the system defines three independent flow loops. Alternately, a system can be provided that employs a “continuous loop” configuration. In a continuous loop configuration, the tubes are coupled to form a single flow path for the treatment fluid. The outlets and inlets of the tubes are coupled to form the flow path. With the “multiple loop” and the “continuous loop” configurations, the pump and fluid treatment reservoir could be completely contained within the condenser box. In that case, all hoses that are used to connect the tubes with the pumping system are also located within the condenser box. 
         [0014]    The system also can employ an “individual loop” configuration. In an individual loop configuration, each tube forms an independent flow path to and from the system supply. In an individual loop configuration, the inlet of each tube receives treatment fluid from the supply through a single inlet, and returns fluid to the supply through a single outlet. This configuration includes a hose that runs from the pumping system to an inlet manifold that distributes the treatment fluid to the inlet of each tube, and an outlet manifold on the outlet side of the of the tube bundle that collects the treatment fluid after it passes through and exits the tubes, and returns it to the pumping system. 
         [0015]    Other configurations, including combinations of these configurations, can be employed. 
         [0016]    The method provided by the present invention includes the steps of providing a supply of treatment fluid, feeding treatment fluid from the supply to the tube, returning treatment fluid to the supply after it has passed through the tube, and providing fluid access to the interior of the tubes using a device that includes an inlet and an outlet, a fluid passage adapted to permit flow of the treatment fluid between the inlet and outlet, and a seal adapted to prevent flow of the fluid between said device and the exterior of the tube. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0017]    The following detailed description of the preferred embodiments may be understood better if reference is made to the appended drawing, in which: 
           [0018]      FIG. 1  is a graphic depiction of a tube bundle, of the type used in condensers; 
           [0019]      FIG. 2  is a side view of the bundle shown in  FIG. 1 , depicting either the inlet or outlet of the tube bundle; 
           [0020]      FIG. 3  is a graphic representation showing a system provided by the present invention installed to clean part of a tube bundle of the type shown in  FIGS. 1 and 2 ; 
           [0021]      FIG. 4  is a graphic representation showing a system provided by the present invention installed to clean a pair of tubes of the bundle shown in  FIGS. 1 and 2 ; 
           [0022]      FIG. 5  shows a system provided by the present invention for treating a section of six tubes of the bundle shown in  FIGS. 1 and 2 , in a multiple loop configuration; 
           [0023]      FIG. 6  is a side view of the equipment shown in  FIG. 5   
           [0024]      FIG. 7  is a side sectional view of a sealing plug provided by the present invention; 
           [0025]      FIG. 8  is a side section view of the sealing plug shown in  FIG. 7  mounted to a tube, with an endpiece mounted to the sealing plug, and a coupling and hose mounted to the endpiece; 
           [0026]      FIG. 9  shows a system provided by the present invention for treating a section of six tubes of the bundle shown in  FIGS. 1 and 2 , in an individual loop configuration; 
           [0027]      FIG. 10  is a side view of the equipment shown in  FIG. 9 ; 
           [0028]      FIG. 11  shows a system provided by the present invention for treating a section of six tubes of the bundle shown in  FIGS. 1 and 2 , in a continuous loop configuration; 
           [0029]      FIG. 12  is a side view of the equipment shown in  FIG. 11 ; 
           [0030]      FIG. 13  is an exploded view of the sealing plug shown in  FIG. 7 ; and 
           [0031]      FIG. 14  is a perspective view of the sealing plug shown in  FIG. 13 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0032]    The preferred embodiments of the present invention shown in the drawing are particularly useful for chemically cleaning scale from the inner surfaces of condenser and heat exchanger tubes. However, the present invention can be used to deliver any type of fluid to the interior of tubes for any purpose. Further, the present invention, including the embodiments shown in the drawing, can be used to treat tubes singly or together in a section of a tube bundle. 
         [0033]    When used as a chemical cleaning system to, for example, clean the interior of condenser tubes, the system can employ any type of chemical cleaning fluid currently used to clean scale and deposits from the inner surfaces of condenser tubes. Chemical cleaning of condenser tubing is a well-known and established industry, and the chemicals that can be used in the cleaning process are very well known. For example, the chemical sold for this purpose by Apex Engineering Products Corporation, of Aurora, Ill., (“Apex”) under the trademark RYDLYME® works well and can be used with the present invention. Similarly, the manifolds, fluid supply reservoirs, pH sensors, control circuits and pumps used in current chemical cleaning systems are well known. Examples are the pumping system components sold by Apex and Goodway Technologies Corporation of Stamford, Conn. Consequently, those components of the system will not be described in detail herein. 
         [0034]      FIGS. 1 and 2  are graphic representations of a tube bundle  1  of a condenser that can be cleaned by the preferred embodiments described herein. Tube bundle  1  is composed of a number of individual tubes  2 . During use of the condenser, as is well known, the interior surfaces of tubes  2  become coated with a scale or deposits. The scale degrades the heat transfer capabilities of tubes  2 , and must be removed.  FIGS. 3 and 4  show a system  10  provided by the present invention that can be used to remove the scale, as well as other foreign material, from the inner surfaces of tubes  2 . 
         [0035]    System  10  includes a reservoir  12  that contains a chemical, of any known type, that removes scale from condenser tubes. A feed  14 , consisting of an inlet line of any known desirable type, is provided to deliver chemical fluid from reservoir  12  to tube bundle  16 .  FIGS. 3 and 4  show system  10  configured to clean a pair of adjacent tubes  18   a  and  18   b.  Four sealing plugs  20  are used to seal the ends of tubes  18  and permit the passage of cleaning fluid to and from tubes  18   a  and  18   b.  A U-connector  22  is provided between two of sealing plugs  20  to allow cleaning fluid to flow from the first tube  18   a  to the second tube  18   b.  Return  24  is installed between the sealing plug  20  that seals the outlet of tube  18   b  and reservoir  12  to permit the cleaning fluid to be recycled to reservoir  12  after it has made a pass through tubes  18   a  and  18   b.  A pump  28  is employed to circulate chemical cleaning fluid from reservoir  12  throughout system  10 . A pH sensor  26  can be provided to measure the pH of the cleaning fluid as it is reused. As the cleaning fluid is recycled through system  10 , its pH rises as it reacts with the scale within tubes  18   a  and  18   b.  As the pH of the cleaning fluid rises, it becomes less effective to react with and dissolve the scale within tubes  18   a  and  18   b.  Sensor  26  can be set to provide an indication that a predetermined pH level has been reached, at which point a fresh supply of cleaning fluid can be provided from reservoir  13  to system  10 , either manually by dumping new chemical into reservoir  12  or automatically by having the pH gauge trigger pump  29  to pump new chemical into reservoir  12 . 
         [0036]    In use, pump  28  forces cleaning fluid from reservoir  12  into feed  14  and into tube  18   a  via a sealing plug  20 . As the cleaning fluid flows through tube  18   a,  it reacts with scale on the inner surface of tube  18   a,  dissolving at least some of it. The fluid exits tube  18   a  through another sealing plug  20 , passes through U-connector  22 , and enters tube  18   b  through a third sealing plug  20 . As with tube  18   a,  the cleaning fluid reacts with scale on the inner surface of tube  18   b  as it flows through it, dissolving some of the scale as it does so. The cleaning fluid exits tube  18   b  through a fourth sealing plug  20 , enters return  24  and is pumped back into reservoir  12 , from which it is recirculated until its pH, as measured by sensor  26 , has risen to a predetermined level. At this point, new cleaning fluid is introduced into system  10  from reservoir  13 , either manually or automatically through pumping system  29 . 
         [0037]      FIG. 3  shows a system  10  that cleans two tubes  18   a  and  18   b.  However, it can be seen that system  10  can be configured to clean a single tube, or a section of tubes of any number. 
         [0038]    For example,  FIGS. 5 and 6  show a system  200  that is used to clean a section  210  of 6 tubes  224 . System  200  is configured in a “multiple loop” configuration. That is, system  200  includes three independent flow paths through section  210 . Each of tube pairs, or loops,  212 ,  214  and  216  carries an independent flow path. Each tube  224  of loops  212 ,  214  and  216  defines an inlet  220  and an outlet  222 . A plug  100  is sealingly mounted in each inlet  220  and each outlet  222 . The construction of plugs  100  is described in detail below. Each plug  100  defines a central passage through which fluid can flow through plug  100  and into or out of a tube  224 . An endpiece  226  is threaded onto the end of each plug  100  to facilitate connection between the inlet  220  or outlet  222  with connecting lines or hoses. Each endpiece  226  can be secured to its respective line using a conventional connector  21 . Connector  21  can be any known connector that is used to mount hardware to hoses, including the type used with compressed air hoses. These connectors use a sliding outer sleeve and ball bearings to attach the hose to a head. Connector  21  can be used in all embodiments of the system shown in the drawing. 
         [0039]    System  200  includes a pump  228  that pumps fluid from a reservoir  224  through system  200 . A pair of hoses  230  carries fluid pumped by pump  228 . Hoses  230  are mounted to a manifold  232 . Manifold  232  defines outlets  234 , each of which is mounted to an inlet hose  236 . Each hose  236  is mounted to an endpiece  226 . Ball valves  223  are mounted in known fashion within each manifold inlet  225  and manifold main inlet  227  to prevent unintended reverse flow. Consequently, pump  228  pumps fluid into hoses  230 , through manifold  232 , through hoses  236  and endpieces  226 , and through plugs  100  into the interior of tubes  224 . 
         [0040]    A U-shaped connecting hose  238  is mounted to the endpiece  226  mounted to the outlet  222  of an inlet pipe  224   a  of each loop  212 ,  214  and  216  and the endpiece  226  mounted to the inlet  220  of the outlet tube  224   b  of the loop. As a result, fluid pumped through the inlet tube  224   a  of each loop  212 ,  214  and  216  exits an outlet  222 , through connecting hose  238  and into outlet tube  224   b.  The fluid then flows through outlet tube  224   b,  plug  100 , endpiece  226 , hose  236 , manifold  232 , hose  230  and back to reservoir  224  and re-circulated through pump  228 . 
         [0041]      FIGS. 9 and 10  show a system  300  that is constructed in an “individual loop” configuration. The construction of system  300  is identical to the construction of system  200 , with the exception of the flow paths defined by system  300 . Rather than configuring pairs of tubes connected by U-shaped hoses to define flow paths, system  300  is configured to define a flow path corresponding to each tube. Thus, system  300  utilizes an inlet manifold  310  defining inlets  311 . Inlets  311  are connected to endpieces  226  via hoses  309  and couplings  21 , which are used to mount hoses  309  to endpieces  226 . Manifold  310  is used to distribute fluid to the inlets  312  of tubes  224  via plugs  100 . System  300  includes an outlet manifold  314  that defines outlets  315  that are connected to the end pieces  226  of the plugs  100  that are mounted to the outlets  320  of the tubes  224 . Outlets  315  are mounted to endpieces  226  via hoses  305  and couplings  21 , which are used to mount hoses  305  to endpieces  226 . Ball valves  322  are mounted in known fashion within each manifold inlet  311  and manifold outlet  315  to prevent unintended reverse flow. Manifold  314  collects fluid that has passed through tubes  224 , and directs the fluid through a single return line  316  back to the fluid reservoir  318 . Typically, line  318  is located outside the containment box (not shown) of the condenser. Consequently, fluid is pumped by pump  228  through inlet manifold  310 , tubes  224 , outlet manifold  314 , return line  316  and back to reservoir  318 . 
         [0042]    Similarly,  FIGS. 11 and 12  show a system  400  that is identical in construction to systems  200  and  300 , with the exception of the manner in which the flow path is defined. System  400  is constructed in a “continuous loop” configuration. System  400  defines a single flow path through tubes  224 . In other words, fluid flows through the tubes  224  of system  400  in completely “series” fashion. All fluid pumped through system  400  flows through all the tubes of the section being treated. A U-shaped connector  410  is employed to channel the flow through adjacent tubes  224 . To illustrate,  FIGS. 11 and 12  show system  400  defining two rows, or layers, of tubes, upper row  412  and lower row  414 . System  400  pumps fluid serially through tubes  224 U of upper row  412 , and then through the tubes  224 L of lower row  414 . Pump  228  pumps fluid into the inlet  416  of first tube  418 . Fluid flows through tube  418  and into a connector  410  that directs the fluid into inlet  420  of second tube  422 . A second connector  410  directs fluid exiting tube  422  into the inlet  424  of a third tube  426 . A third connector  410  directs the fluid downwardly to the inlet of the first tube (not shown) of the lower row  414 . As with upper layer  412 , another U-connector (not shown) directs the fluid to the second tube (not shown) of row  414 . Finally, a fifth connector  410  directs the fluid to the inlet  428  of the sixth, and last, tube  430 . The fluid is returned to the fluid reservoir  432  via line  434 . As is well known in the industry, ball valves  436  are provided in lines  438  and  434  to prevent reverse flow. 
         [0043]    Referring to  FIGS. 7 ,  8 ,  13  and  14  a sealing plug  100  provided by the present invention can be used to seal the ends of tubes to provide fluid access to the interior of a tube. Sealing device  100  can be used in systems that circulate cleaning fluid through tubes to clean the interior surfaces of the tubes. As is described above, sealing device  100  can be used in systems of the type shown in the drawing, and to allow passage of the cleaning fluid into and out of the tubes. It should be understood, however, that plug  100  can be used in any system that introduces a fluid into tubes for any purpose. 
         [0044]    Plug  100  includes a threaded core  102  made from a suitable plastic or metal material, such as plastic: Delrin or acetal 570 or metal: stainless steel. Core  102  defines a flange  104  at one end, and a threaded section  106  at the other end. At least one cylindrical sealing sleeve  108  is provided, which defines a central bore  110 , which is sized to be received along central section  112  of core  102 . At least one sleeve  108  is mounted on section  112  of core  102 . If more than one sleeve  108  is used, a plastic washer  113  is mounted between each pair of sleeves  108 . Where, as with the embodiment shown in the drawing, a pair of sleeves  108  is employed, a single washer  113  is mounted between sleeves  108 . Regardless of the number of sleeves  108  employed, a washer  114  is mounted on core  102  adjacent the end of the outermost sleeve  108 . Washer  113  will have a smaller diameter than  114  to enable the diameter of washer  113  to more closely match the diameter of sleeves  108 . A nut  116  is threaded onto the threaded end  106  of core  102 , and bears against washer  114 . The diameter of washer  114  is chosen to be larger than the inner diameter of the tubes in which plug  100  is mounted to facilitate placement of plug  100  in a consistent location with respect to the tubes. That is, washer  114  acts like a “stop” that prevents inadvertent placement of plug  100  to far within the tube. Washers  113  and  114  function as the bearing surfaces against which the force generated by nut  116  is exerted against the ends of sleeves  108 , which in turn operates to expand sleeves  108  and force them into sealing engagement with the interior of tube  118  (see, particularly,  FIG. 8 ). The expansion of the sleeves  108  against the interior surface of tube  118  also operates to fix the position of plug  100  within tube  118 . 
         [0045]    Core  102  defines a passage  120  through which fluid can pass through core  102 . Endpiece  226  includes a threaded section  600  which is threaded onto threaded section  106  of plug  100  to mount endpiece  226  to plug  100 . A hose or line  120  can then be mounted to endpiece  226  using a conventional coupling  21 . 
         [0046]    To mount a plug  100  within a tube  118 , a sleeve  108  is mounted onto center section  112  of plug  100 . The length of section  112  and the number of sleeves  108  can vary. The length of section  112  will typically be between three and four inches and plug  100  will typically have one washer  113  separating two flexible bushings or sleeves  108  and an additional washer  114  separating sleeves  108  and nut  116 , which will typically provide an effective seal. These configurations can be changed to alter the nature of the seal as is well known in the art. Generally, the effectiveness of the seal between the plug  100  and a tube increases as the number of washers  113  increases and the length of the bushings  108  decreases. However, as will be appreciated by those in the art, the increased number of washers  113  will begin to compromise the effectiveness of the seal. A plug with two sealing sleeves  108  separated by a washer  113  will provide an effective seal in most situations. If it is found that the seal is not adequate, those in the art will appreciate how to modify the number and length of the sleeves  108  to improve the seal. For example, if a tube is severely eroded and, consequently, achieving a seal is difficult, the plug  100  may need to be made longer or more washers  113  will need to be added, which would mean more, and shorter, sleeves  108  would be provided on the plug  100 . 
         [0047]    Flange  104  is inserted into a tube  118  that is to be cleaned, and a nut  116  is threaded onto threaded end  106  of plug  100 . As nut  116  is tightened, sleeves  108  expand radially to provide a seal between plug  100  and the interior of tube  118 . In this regard, the washers  114  provide bearing surfaces for the pressure exerted on sleeves  108  by nut  116 , and ensure more uniform expansion of sleeves  108 . When plugs  100  are fully mounted to each end of tube  118 , fluid is free to pass into and out of tube  118 . 
         [0048]    Although the invention has been described with reference to the above embodiments, it will be apparent to one of the ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit or scope of the invention. For example, it is to be understood that changes may be made in details, including in matters of shape, size, and arrangement of parts in accordance with the appended claims. The foregoing description of embodiments of the invention have been presented only for purposes of illustration and description. These embodiments were chosen and described to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular uses contemplated. Accordingly, the scope of the invention will be defined by the attached claims not by the above detailed descriptions.