Abstract:
A pumping system for pumping a mixture, e.g. a drilling fluid mixture, containing liquid and solids, the pumping system including a container, centrifugal pump apparatus for pumping the mixture, the pump apparatus including a pump shaft, a drive motor, a shaft packing structure, and bearing apparatus around the pump shaft, the packing structure, bearing apparatus and part of the pump shaft within an enclosed non-vented housing. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 CFR 1.72(b).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is directed to centrifugal pumps; to systems using them; and, in certain particular aspects, to such systems for pumping solids-laden drilling fluids. 
         [0003]    2. Description of Related Art 
         [0004]    The prior art discloses a wide variety of centrifugal pumps; systems that employ them; and systems with such pumps for pumping drilling fluid laden with drilled solids and other solid components; for example, and not by way of limitation, see U.S. Pat. Nos. 5,456,580; 5,662,807; 5,846,440; 6,096,228; 6,170,580; 6,179,071; 6,276,824; 6,345,672; 6,406,255; and 6,808,354, all of said patents incorporated fully herein for all purposes. 
         [0005]    Pumping systems which employ centrifugal pumps are used to pump mixtures and slurries that contain solids. In certain particular aspects, such systems pump fluids used in the drilling of earth wellbores, tunneling and excavating. Drilling fluids can contain hazardous material, oil, solids, debris, rock, and shale cuttings. 
         [0006]    The safe and efficient handling of drilling fluid and its proper disposal result in significant expense in drilling a wellbore. 
         [0007]    There has long been a need, recognized by the present inventors, for effective and efficient systems employing centrifugal pumps for pumping mixtures with solids therein. There has long been a need, recognized by the present inventors, for effective and efficient systems for pumping solids-laden drilling fluids. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention discloses, in certain aspects, systems for pumping mixtures with solids therein. In certain aspects, such systems include a container or tank for receiving and holding the mixture; apparatus for moving the mixture within and from the container; and one or more centrifugal pumps for transferring the mixture from the container to storage or disposal (and/or to mix the mixture within the container to make it homogeneous). 
         [0009]    In certain aspects the mixture contained within a container is a slurry which includes a fluid or fluids and solids in the fluid. In one particular aspect, the mixture is a slurry of drilling fluid from a wellbore with solids (e.g. drilled cuttings, drilled debris, etc.) therein. 
         [0010]    In certain particular aspects, the present invention discloses a centrifugal pump with a packing structure for a pump shaft. The packing structure includes seals that act as containment barriers to prevent outside contamination from entering a pump housing and contacting the shaft and other parts. In certain aspects, the packing structure is sealed within a non-vented space below bearings, a space in which a positive pressure is maintained. Also, with seals isolated and under pressure, and located in a non-vented space, as temperature builds up during operation, lubricant adjacent the seals expands, increasing pressure as compared to pressure external to the packing structure, which contributes to maintaining the seals in isolation and to prohibiting contaminants from entering the system and flowing to the bearings. Thus, the life of parts, e.g. shafts and bearings, can be extended. 
         [0011]    In certain aspects, the present invention discloses pumping systems for pumping a drilling mixture containing liquid drilling fluid and solids (e.g., debris, drilled cuttings, etc.) entrained in the liquid drilling fluid, the pumping systems including: a container for receiving and holding the drilling mixture; centrifugal pump apparatus for transferring the drilling mixture from the container, the centrifugal pump apparatus including a pump shaft, a motor to drive the pump shaft, a packing structure around the pump shaft and bearing apparatus around the pump shaft, a housing, the housing comprising an enclosed non-vented structure; and the packing structure, bearing apparatus and part of the pump shaft within the housing. 
         [0012]    The present invention discloses, in certain aspects, centrifugal pump apparatus including: a pump shaft; a motor to drive the pump shaft; a packing structure around the pump shaft; bearing apparatus for the pump shaft; a non-vented housing able to contain lubricant and/or grease under pressure; and the packing structure, bearing apparatus and part of the pump shaft within the housing. 
         [0013]    In certain aspects, the present invention discloses methods for pumping a mixture containing liquid and solids (in one particular aspect, a mixture of drilling fluid and drilled solids), the method including: feeding the mixture from a container for receiving and holding the mixture to a centrifugal pump apparatus for transferring the mixture from the container, the centrifugal pump apparatus being any according to the present invention; and with the centrifugal pump, pumping the mixture from the container. 
         [0014]    The present invention discloses, in certain aspects, pumping systems for pumping a mixture containing liquid and solids, the pumping systems including: a container for receiving and holding the mixture; centrifugal pump apparatus for transferring the mixture from the container; the centrifugal pump apparatus including a non-vented housing that is able to hold pressure. 
         [0015]    What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, there are other objects and purposes which will be readily apparent to one of skill in this art who has the benefit of this invention&#39;s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide: 
         [0016]    New, useful, unique, efficient, non-obvious pumping systems; methods of their use; and centrifugal pump apparatus for use with them; 
         [0017]    Such pumping systems with a pump having an isolated packing structure with a relatively high internal pressure which effectively prevents contaminants from entering the system and flowing to items above the packing structure, e.g. preserving vital parts, e.g. bearings and shafts; 
         [0018]    Such pumping systems and methods in which a packing structure is located in a non-vented space; and 
         [0019]    In certain aspects, such a pump in which lubricant heated during operation increases pressure on the packing structure. 
         [0020]    Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures, functions, and/or results achieved. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention. 
         [0021]    The present invention recognizes and addresses the problems and needs in this area and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention&#39;s realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of certain preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent&#39;s object to claim this invention no matter how others may later attempt to disguise it by variations in form, changes, or additions of further improvements. 
         [0022]    The Abstract that is part hereof is to enable the U.S. Patent and Trademark Office and the public generally, and scientists, engineers, researchers, and practitioners in the art who are not familiar with patent terms or legal terms of phraseology to determine quickly from a cursory inspection or review the nature and general area of the disclosure of this invention. The Abstract is neither intended to define the invention, which is done by the claims, nor is it intended to be limiting of the scope of the invention in any way. 
         [0023]    It will be understood that the various embodiments of the present invention may include one, some, or all of the disclosed, described, and/or enumerated improvements and/or technical advantages and/or elements in claims to this invention. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0024]    A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain preferred embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or legally equivalent embodiments. 
           [0025]      FIG. 1  is a perspective view of a pumping system according to the present invention. 
           [0026]      FIG. 2  is a perspective view of the system of  FIG. 1 . 
           [0027]      FIG. 3  is a side schematic side view of part of the system of  FIG. 1 . 
           [0028]      FIG. 4  is a perspective view of a pump according to the present invention of the system of  FIG. 1 . 
           [0029]      FIG. 5  is a front view of the pump of  FIG. 4 . 
           [0030]      FIG. 6  is an underside view of the pumps of  FIG. 4 . 
           [0031]      FIG. 7  is a cutaway view along line  7 - 7  of  FIG. 5 . 
           [0032]      FIG. 8  is a cross-sectional view of the pump along line  8 - 8  of  FIG. 6 . 
           [0033]      FIG. 9A  is a side view of a pump according to the present invention. 
           [0034]      FIG. 9B  is a cross-sectional view along line  9 B- 9 B of the pump of  FIG. 9A . 
           [0035]      FIG. 9C  is an enlarged view of part of the pump of  FIG. 9B . 
           [0036]      FIG. 10A  is an exploded perspective view of part of the pump of  FIG. 9A . 
           [0037]      FIG. 10B  is an enlarged perspective view of part of the pump of  FIG. 10A . 
           [0038]      FIG. 11  is a cross-section view of a prior art seal useful with the pump of  FIG. 9A . 
       
    
    
       [0039]    Presently preferred embodiments of the invention are shown in the above-identified figures and described in detail below. Various aspects and features of embodiments of the invention are described below and some are set out in the dependent claims. Any combination of aspects and/or features described below or shown in the dependent claims can be used except where such aspects and/or features are mutually exclusive. It should be understood that the appended drawings and description herein are of preferred embodiments and are not intended to limit the invention or the appended claims. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. In showing and describing the preferred embodiments, like or identical reference numerals are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
         [0040]    As used herein and throughout all the various portions (and headings) of this patent, the terms “invention”, “present invention” and variations thereof mean one or more embodiment, and are not intended to mean the claimed invention of any particular appended claim(s) or all of the appended claims. Accordingly, the subject or topic of each such reference is not automatically or necessarily part of, or required by, any particular claim(s) merely because of such reference. So long as they are not mutually exclusive or contradictory any aspect or feature or combination of aspects or features of any embodiment disclosed herein may be used in any other embodiment disclosed herein. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0041]      FIGS. 1-2  illustrate a system  10  according to the present invention which has a container  8 ; a handling system  4 ; and an auger  6 . Any suitable container or tank of any configuration and dimensions may be used. As shown, the container  8  is an elongated tank for receiving and holding a mixture with liquid and solids. In certain particular aspects, the container  8  is designed so that it can be easily transported from location to location; e.g., land locations, on an offshore platform, or to and from other remote locations. 
         [0042]    Optionally, the container  8  has a pair of rails  18  supported by braces  20 . The handling system  4 , which moves on the rails  18 , is mounted on a platform or trolley  22  which has a set of wheels  24 . The platform  22  has a pair of sprocket wheels  26  which are propelled by a motor and which engage the rails  18  to move the handling system  4  back and forth from one end of the container  8  to the other. 
         [0043]    The handling system  4  includes a shovel  28  for moving material within and from one end to the other end of the container. 
         [0044]    The handling system  4  includes a pump system  30  according to the present invention for pumping material from the container  8 . The pump system  30  includes at least one pump according to the present invention. 
         [0045]    As shown in  FIG. 2 , the handling system  4  and the shovel  28  have moved within the container  8 , pushing material toward one end of the container  8 . Here the auger  6  may be activated to move material from the container  8 . 
         [0046]      FIG. 3  shows shovel  28  connected to a boom ladder  40 , extending from a first extension member  42 . The boom ladder  40  and the first extension member  42  are pivotally attached by a pin  44 . The first extension member  42  is attached to the platform  22 . A shovel blade  48  is attached to a second extension member  46 . An optional detachable shovel blade  50  is attached to the boom member  40  via a third extension member  52 . 
         [0047]    The pump system  30  includes a pump motor  54  which is adapted to a pump case cylinder  56 . A guard  58  is, optionally, included so that a suction inlet  60  is raised enough off the bottom so that large solids do not enter the pump or block off the suction inlet  60 . A disposal conduit  62 , leading from the pump case cylinder  56 , conducts material to a swivel joint conduit  64  for ultimate disposal. Optionally, an oscillator  70  oscillates the boom ladder  40 . 
         [0048]    Referring now to  FIG. 4 , the motor  54  of the pump system  30  is operatively associated with an impeller assembly  200 . The pump motor  54  may be any suitable commercially available motor. The shaft from the motor extends to the pump case cylinder  56 , with the impeller  200  encased within the pump case cylinder  56 . A shaft cover  250  extends from the motor  54  to a top  252  of the pump case cylinder  56 . The cover  250  contains supports and a top flange  254  and a bottom flange  256 , with the top flange  254  connected to a motor flange  258 . Lines for the motor include an input line  260  and output line  262  for hydraulic power fluid input and output. 
         [0049]    The disposal conduit  62  leads from the pump case cylinder  56 . The pump case cylinder  56  has an extension section  264  that stretches to the generally vertically oriented disposal conduit  62 . The extension section  264  also extends to a slurry gate  122  with a passage  124 . Brackets  265 ,  266  are used for mounting the hydraulic motor and legs  58 .  FIG. 5  depicts the impeller assembly  200  and the protrusion of blade ends from a pump case bottom  267 . The slurry gate  122  provides an outlet for the system. 
         [0050]    In  FIG. 6 , the underside portion of the pump system  30  is illustrated and the impeller assembly  200  is shown projecting from the bottom of the pump case. The extension section  264  extends from the cylindrical pump case cylinder  56 . The slurry gate  122  contains a rod  268  that is used to position the gate in an open or closed position. Alternatively, an hydraulic cylinder apparatus is used to move the gate. The pump both mixes the slurry and discharges it. 
         [0051]    As shown in  FIG. 7 , a plate  202  is disposed within the pump case cylinder  56 . An outer periphery  270  is placed in relatively close relationship with an inner cylindrical wall  272  of the pump case cylinder  56 . Material (e.g. mixture; slurry) enters the pump case cylinder  56  from a center inlet area  208  and is directed through the impeller assembly  200  and outward towards the inner wall  272  due to the centrifugal force generated by rotation. Arrows  274  depicted the travel area of the slurry about the inner circular wall  272  to the extension section  264  which in turn allows passage to the disposal conduit  62 . The extension section  264  and the disposal conduit  62  are in fluid communication with one another. The material is then lifted by the pump system  30  up into and out of the conduit  62 . 
         [0052]      FIG. 8  shows the pump system  30  with a rotative shaft  276  that extends from the motor  54 . The shaft cover  250  is generally a cylindrical member with an inner bore. The inner bore has disposed therein a first set of roller bearings  278  and second set of roller bearings  280  that are separated by a spacer  282 . The shaft  276  is threadedly connected to the impeller assembly  200  so that, when the shaft  276  is rotated by the motor, the impeller assembly  200  and associated blades rotate thereby loading the pump case cylinder  56  with the material as previously described. 
         [0053]    A generally circular opening  284  is at the bottom  267  of the case  56 . In one aspect, a wear plate  286  is, optionally, added which adds to the structure and reinforces the pump case  56  thereby protecting from the erosional forces produced during pumping. The slurry gate  124  provides a mixing outlet for the material. 
         [0054]    The pump system  30  includes a packing structure  170  according to the present invention which may be any packing structure according to the present invention disclosed herein. The packing structure  170  surrounds the shaft  276 . 
         [0055]      FIGS. 9A and 9B  show a pump system  300  according to the present invention which has a driving shaft  332  driven by a motor  334 . The driving shaft  332  is connected to an impeller assembly (not shown; any suitable impeller, e.g., but not limited to, like the impeller assembly  200 ,  FIG. 7 ). 
         [0056]    The driving shaft  332  extends through a housing  336  and has a lower threaded end  338  for connection to an impeller assembly. The motor  334  is mounted on a plate  342 . Flanges  344  are connected to the housing  336  and a base  346 . 
         [0057]    A bearing spacer  350  spaces-apart upper bearings  352  and lower bearings  354  which facilitate rotation of the driving shaft  332 . Lubricant is contained in a space  356  and encompasses the bearings. This lubricant (e.g. high viscosity lubricant e.g., gear oil) is introduced into the space  356  through a port  358  which is closed off with a plug  362  (e.g. once the space is devoid of air). A removable snap ring  364  holds the bearings  352 ,  354  and the bearing spacer  350  in place. Lubricant can flow from the port  358  down to the lowest of the lower bearings  354 . The space  356  includes the bearings  352 ,  354  and the open area below the bearings  352  and space above the bearings  354 . 
         [0058]    A packing structure  310  according to the present invention surrounds the driving shaft  332 ; maintains the bearings in place; and prevents contaminants from entering the space  356  which could damage or erode parts of the system, e.g. the shaft  332  and/or the bearings. 
         [0059]      FIGS. 9C ,  10 A and  10 B show the packing structure  310  in detail. According to the present invention, at least one seal can be used and at least one seal retainer ring can be used. As shown in  FIG. 9B  and  FIG. 9C  there are a plurality of seals  311 ,  312 ,  313 ,  314  held in place by retainer rings or “floor members,” a top floor member  316  and a bottom floor member  318 . In certain aspects the seals  311 - 314  are made of hard rubber and steel and the floor members are made of high wear resistant material such as, e.g., 4140 steel. A single floor member may be used. The floor members have cutouts or recesses R for the seals. The floor members  316 ,  318  are exteriorly threaded and engage interior threading  337   a  and  337   b  on the housing  336 . A retainer or “hat”  322  is used between the exterior of the shaft  332  and the seals  311 - 314 . A top end of the retainer  322  abuts a shoulder  332   a  of the shaft  332 . The retainer has a base  322   b  and a cylinder  322   c . The cylinder  322   c  encircles part of the shaft  332 . The retainer  322  rotates with the shaft  332 . An impeller (e.g. an impeller/assembly as in  FIG. 4 ) will abut the retainer  322 , locking it in place and sealing the bearing housing. The retainer  322  acts as a barrier inhibiting or preventing contaminants and debris from contacting the pump shaft. 
         [0060]    The upper and lower floors exceed the interior diameter of the bearings and provide housings for the double set of seals that isolate the bearing area. The floor members also act as temporary supports and guides for the shaft  332 , e.g. if a bearing failure occurs. This auxiliary back-up support and guidance function allows for the pump operation to continue until a safe shut down can be made for replacement. 
         [0061]    To pressurize the seals  311 - 314  against the shaft  332 , grease under pressure is introduced through a grease fitting  324  into the space occupied by the seals  311 - 314  and the floor members  316 ,  318 . The pressure of this grease, confined about the seals, provides a positive internal pressure at the location of the packing structure  310 . This positive internal pressure is greater than atmospheric pressure external to the bearing housing and is greater than an increased external pressure, e.g. such an increased pressure caused by suction created by impeller turbulence. It is within the scope of the present invention to use one, two, three, four, five, six or more of the seals  311 - 314  and/or to use one, two, three or more of the floor members  316 ,  318 . A seal hammer can be used to install the seals evenly in the floor members. 
         [0062]      FIG. 11  shows a seal member  360  which has a body  326  with a rubber ring  364  in a recess  366 . In one aspect, the seal member  360  is used with the rubber ring  364  facing upwardly. The seal  311  prevents bearing lubricant from flowing down into the packing system  300 . Any suitable seal may be used instead of the seal members  360 . 
         [0063]    The present invention, therefore, provides in at least certain embodiments, a pumping system for pumping a drilling mixture containing liquid drilling fluid and solids entrained in the liquid drilling fluid, the pumping system including: a container for receiving and holding the drilling mixture; centrifugal pump apparatus for transferring the drilling mixture from the container; the centrifugal pump apparatus including a pump shaft, a motor to drive the pump shaft, a packing structure around the pump shaft and bearing apparatus around the pump shaft; a housing, the housing which is an enclosed non-vented structure; and the packing structure, bearing apparatus and part of the pump shaft within the housing. Such a system may have one or some, in any possible combination, of the following: seal apparatus for sealing the housing to prevent the ingress of contaminants into the housing; a lubricant port through the housing for providing lubricant to the bearing apparatus; lubricant within the housing for lubricating the bearing apparatus, the lubricant expandable upon heating to increase pressure within the housing to inhibit contaminants from entering the housing through the pump-shaft/housing interface; the seal apparatus containing at least one seal; the packing structure surrounding the pump shaft and maintaining the bearing apparatus in position adjacent the pump shaft and above the packing structure; the packing structure inhibiting contaminants from flowing to the bearing apparatus; a retainer with a base and a cylinder, the cylinder encircling a portion of the drive shaft and the base abutting a bottom of the packing structure; the retainer acting as a barrier inhibiting contaminants from contacting the pump shaft; seal apparatus for sealing the housing to prevent the ingress of contaminants into the housing, the seal apparatus including at least one seal, and the at least one seal sealingly contacting an exterior surface of the retainer ring&#39;s cylinder; the packing structure including at least one seal, and at least one retainer ring for holding the seal in a sealing position; the at least one retainer ring having a ring diameter, the bearing apparatus having a bearing diameter, and the ring diameter greater than the bearing diameter; impeller apparatus on the pump shaft, the impeller apparatus abutting the retainer; the retainer supporting and guiding the pump shaft in the event of failure of the bearing apparatus; a grease port for introducing grease into the housing for the at least one seal of the seal apparatus; and/or grease adjacent the at least one seal, the grease under pressure to provide a positive internal pressure at a location of the packing structure. 
         [0064]    The present invention, therefore, provides in at least certain embodiments, a pumping system for pumping a drilling mixture containing liquid drilling fluid and solids entrained in the liquid drilling fluid, the pumping system including: a container for receiving and holding the drilling mixture; centrifugal pump apparatus for transferring the drilling mixture from the container; the centrifugal pump apparatus including a pump shaft, a motor to drive the pump shaft, a packing structure around the pump shaft and bearing apparatus around the pump shaft; a housing which is an enclosed non-vented structure; the packing structure, bearing apparatus and part of the pump shaft within the housing; seal apparatus for sealing the housing to prevent the ingress of contaminants into the housing; the packing structure surrounding the pump shaft and maintaining the bearing apparatus in position adjacent the pump shaft and above the packing structure; the packing structure inhibiting contaminants from flowing to the bearing apparatus; a retainer with a base and a cylinder, the cylinder encircling a portion of the drive shaft and the base abutting a bottom of the packing structure; and the retainer acting as a barrier inhibiting contaminants from contacting the pump shaft. 
         [0065]    The present invention, therefore, provides in at least certain embodiments, a centrifugal pump apparatus including: a pump shaft; a motor to drive the pump shaft; a packing structure around the pump shaft; bearing apparatus around the pump shaft; a housing which is a non-vented housing; and the packing structure, bearing apparatus and part of the pump shaft within the housing. 
         [0066]    The present invention, therefore, provides in at least certain embodiments, a method for pumping a mixture containing liquid and solids, the method including: feeding the mixture from a container for receiving and holding the mixture to a centrifugal pump apparatus for transferring the mixture from the container, the centrifugal pump apparatus including a pump shaft, a motor to drive the pump shaft, a housing, a packing structure around the pump shaft and bearing apparatus around the pump shaft, the housing comprising a non-vented housing, the packing structure, bearing apparatus and part of the pump shaft within the housing; and, with the centrifugal pump, pumping the mixture from the container. 
         [0067]    The present invention, therefore, provides in at least certain embodiments, a pumping system for pumping a mixture containing liquid and solids, the pumping system including: a container for receiving and holding the mixture; centrifugal pump apparatus for transferring the mixture from the container; the centrifugal pump apparatus including housing, a pump shaft, a motor to drive the pump shaft, a packing structure around the pump shaft and bearing apparatus around the pump shaft, the housing being a non-vented enclosure; and the packing structure, bearing apparatus and part of the pump shaft within the housing. 
         [0068]    In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to the step literally and/or to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. § 102 and satisfies the conditions for patentability in § 102. The invention claimed herein is not obvious in accordance with 35 U.S.C. § 103 and satisfies the conditions for patentability in § 103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. § 112. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims. All patents and applications identified herein are incorporated fully herein for all purposes. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.