Patent Publication Number: US-11643915-B2

Title: Drive equipment and methods for mobile fracturing transportation platforms

Description:
PRIORITY CLAIM 
     This is a divisional of U.S. Non-Provisional application Ser. No. 17/377,884, filed Jul. 16, 2021, titled “DRIVE EQUIPMENT AND METHODS FOR MOBILE FRACTURING TRANSPORTATION PLATFORMS,” which is a divisional of U.S. Non-Provisional application Ser. No. 17/301,305, filed Mar. 31, 2021, titled “DRIVE EQUIPMENT AND METHODS FOR MOBILE FRACTURING TRANSPORTATION PLATFORMS,” now U.S. Pat. No. 11,111,768, issued Sep. 7, 2021, which claims priority to and the benefit of, under 35 U.S.C. § 119(e), U.S. Provisional Application No. 62/705,055, filed Jun. 9, 2020, titled “DRIVE EQUIPMENT AND METHODS FOR MOBILE FRACTURING TRANSPORTATION PLATFORMS,” the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The application generally relates to mobile power units and, more specifically, drive equipment and methods for usage and installation on mobile fracturing transportation platforms. 
     BACKGROUND 
     Conventional hydraulic fracturing horsepower units often utilize diesel reciprocating engines to drive positive displacement reciprocating pumps. These pumps generally form a part of a fracturing fluid system which often includes auxiliary equipment such as blenders, hydration, and chemical pumps. This auxiliary equipment is commonly referred to as backside equipment and may be powered by diesel reciprocating deck engines or small mobile diesel generators. 
     The fracturing industry has been making strides to reduce emissions and footprint. Specifically, the fracturing industry has been making strides to reach government mandated tier 4 emissions standards, namely a government mandated reduction in harmful exhaust gases for diesel powered equipment. One way the fracturing industry is moving towards tier 4 emissions is to replace the diesel reciprocating engines with turbine engines that are fueled with natural gas to directly drive hydraulic fracturing pumps. This allows fracturing horsepower units to reach tier 4 emission standards. The backside equipment, however, remains driven by engines or generators that struggle with meeting or otherwise do not meet tier 4 emission standards. 
     In addition, often it is necessary to run multiple diesel engines to power backside equipment, and running multiple diesel engines to power backside equipment may increase costs both through fuel consumption and maintenance. The reciprocating engines on the auxiliary equipment, specifically blenders and hydration units, may include a transmission and gearbox inline to power a pump. These added parts may add another mode of failure and further increase maintenance spending. 
     One method that has been used for achieving tier 4 emissions standards for the backside equipment is to convert the backside equipment to an electrical fracturing fleet. These electrical fracturing fleets generally use a standalone gas turbine engine generator trailer, or other transportation platform as understood by those skilled in the art, to produce electrical power that is distributed through electrical switch gear to drive electrical motors directly coupled to the horsepower units. These electrical motors may be controlled with a high efficiency, high power factor active front end drive (AFE) or variable frequency drive. The standalone gas turbine engine generator trailer also may be rigged into the backside equipment to power the backside equipment. Although this arrangement may meet tier 4 emission standards under some conditions, an electrical fracturing fleet requires a dedicated generator unit. A dedicated generator unit requires additional cost to develop, build, and maintain. 
     Applicant has recognized that using an electrical fracturing fleet with a dedicated turbine generator may not always be feasible or economical. For example, electrical generators are commonly mounted on skids which may restrict mobility and requires extensive rig up procedures. In addition, power transfer may not always be efficient depending on cable lengths and motor efficiencies. Further, weather conditions also play a factor as the fracturing service may be supplied in a wide range of weather conditions which may affect service. For example, high temperature conditions may require different cooling packages since generators start losing efficiency at higher temperatures. During high temperature conditions resistance in generators decreases causing lower efficiencies, if this effect is too high, running an electrical generator may no longer be economical. As such it is not always beneficial to have a dedicated generator. 
     SUMMARY 
     In today&#39;s oil and gas service environment, flexibility and adaptability may be important. Applicant also has recognized that due to the nature of hydraulic fracturing, more horsepower than what is readily available is often required. Having a mobile power unit that may drive a hydraulic fracturing pump or an electric power generator may be beneficial in terms of flexibility. Accordingly, Applicant further has recognized that being able to quickly configure a mobile power unit driving a turbine generator into a mobile power unit driving a reciprocating pump may allow fracturing equipment to meet these changing horsepower demands and effectuate tier 4 emission standards. In other cases, due to site footprints, providing horsepower is the priority for all available space. As such, having a dedicated generator may not be the best solution for power generation. 
     Applicant still further has recognized that another drawback of a dedicated generator is the upfront engineering and cost to produce the unit. The generators may require extensive engineering hours along with different components and parts. The benefit of having a turbine driven fracturing pump that may be configured into an electrical generator provides flexibility and adaptability and may save costs by utilizing similar parts and components. 
     According to embodiments of systems and methods of the disclosure, for systems that include a natural gas turbine generator, the backside equipment such as the diesel deck engines, gearboxes, and transmissions may be removed, and instead, backside equipment, such as centrifugal or other types of pumps, may be powered with higher reliability electric pumps. One of the most common modes of failure with this backside equipment is hydraulic leaks or failures. With an electric motor, the need for hydraulic circuits to power the backside equipment may be removed. Thus, converting the backside equipment to be driven by electrical motors may also increase reliability of the backside equipment and, thus, increase uptime or reduce maintenance costs. Also, having electric motors connected to or coupled to pumps, as opposed to hydraulic motors, may yield more efficiency in an electric fleet arrangement, and this, in turn, may result in an improvement in running costs and a reduction in heat rejection which removes need, in some instances, for high air to oil cooler systems, as will be understood by those skilled in the art. 
     According to embodiments of systems and methods, it also is anticipated that the natural gas turbine fleets may be converted to be completely electric. With enough turbine generator units and a power distribution system, the natural gas turbine fleets may remove the tier 4 diesel deck engines on the fracturing pumps that often are used to start the turbines and run the on-board auxiliary equipment. This may reduce costs as tier 4 diesel deck engines may be expensive. 
     Further, this application is directed to embodiments of high pressure pumps and power generators that readily are installable on mobile fracturing transportation platforms, such as trailers, and that may include a dual fuel, dual shaft turbine engine mounted to the mobile fracturing trailer selectively to drive either the high pressure pumps or the power generators when installed on the mobile fracturing trailer. 
     According to one embodiment of the disclosure, a mobile power unit includes a gas turbine engine, a drive shaft, a reduction gearbox, and a transportation platform. The gas turbine engine includes an engine output shaft that rotates to provide energy from the gas turbine engine. The reduction gearbox is disposed between the engine output shaft and the drive shaft such that the speed of rotation of the engine output shaft to a speed of rotation of the drive shaft is reduced. The reduction gearbox may have a ratio in a range of 5:1 to 20:1. The transportation platform includes a drive equipment receiver that is configured to receive drive equipment therein such that the drive equipment is positioned to be connected to the drive shaft. The gas turbine engine is mounted to the transportation platform so that the reduction gearbox and the drive shaft are attached to the transportation platform. The transportation platform having a first configuration when a pump is installed in the drive equipment receiver such that the pump is driven by the gas turbine engine. The pump connected to the drive shaft when the pump is installed in the drive equipment receiver such that the pump is configured to provide high pressure fluid when driven by the gas turbine engine. The transportation platform having a second configuration when an electrical generator is installed in the drive equipment receiver such that the electrical generator is driven by the gas turbine engine. The electrical generator being connected to the drive shaft and configured to provide electrical power when driven by the gas turbine engine. 
     In embodiments, the reduction gearbox may have a ratio of 11:1. The electrical generator may include a generator gearbox that is configured to step up a speed of rotation of the drive shaft. The generator gearbox may have a ratio in a range of 1:1.25 to 1:5. 
     In another embodiment of the disclosure, a mobile power unit includes a gas turbine engine, a drive shaft, a fixed reduction gearbox, and an electrical generator. The gas turbine engine includes an engine output shaft. The drive shaft is driven by the gas turbine engine and is configured to connect to a hydraulic fracturing pump so that the pump provides high pressure fluid for hydraulic fracturing. The fixed reduction gearbox is positioned between the gas turbine engine and the drive shaft. The reduction gear box reducing a speed of rotation of the engine output shaft of the gas turbine engine to a speed for rotation of the drive shaft. The electrical generator is connected to the drive shaft and includes a step up generator gearbox and an alternator. The alternator being configured to generate electrical power. 
     In embodiment, the fixed reduction gearbox may have a ratio in a range of 5:1 to 20:1, e.g., 11:1. The fixed reduction gearbox may reduce a maximum speed of the drive shaft to 1500 RPM. The alternator may be a permanent magnet alternator having 2 or 4 poles. 
     In yet another embodiment of the disclosure, a well pad includes a plurality of mobile power units, and a blender unit, a hydration unit, or a chemical additive unit. Each mobile power unit of the plurality of mobile power units includes a gas turbine engine, a drive shaft, a reduction gearbox, and a transportation platform. The gas turbine engine includes an engine output shaft that rotates to provide energy from the gas turbine engine. The reduction gearbox is disposed between the engine output shaft and the drive shaft such that the speed of rotation of the engine output shaft is reduced to a speed of the drive shaft. The reduction gearbox may have a ratio in a range of 5:1 to 20:1. The transportation platform may include a drive equipment receiver defined thereon. The gas turbine engine mounted to the transportation platform such that the reduction gearbox and the drive shaft are secured to the transportation platform. The well pad includes a first mobile power unit that includes an electrical generator installed in the drive equipment receiver of the transportation platform such that the electrical generator is driven by the gas turbine engine of the first mobile power unit. The well pad includes a second mobile power unit that includes a hydraulic fracturing pump installed in the drive equipment receiver of the transportation platform such that the hydraulic fracturing pump is driven by the gas turbine engine of the second mobile power unit. The blender unit, hydration unit, or chemical additive unit includes a first pump that includes an electric motor to rotate the first pump. The first pump receiving electrical power from the electrical generator of the first mobile power unit. 
     In yet another embodiment of the disclosure, a method of changing drive equipment of a mobile power unit includes operating a first mobile power unit in a first configuration, operating the first mobile power unit in a second configuration, and interchanging the first mobile power unit between the first configuration and the second configuration. Operating the first mobile power unit in the first configuration includes a gas turbine engine of the first mobile power unit driving a pump to provide high pressure fluid. The pump connected to a drive shaft that has a maximum speed of rotation in a range of 1000 RPM to 1700 RPM. Operating the first mobile power unit in the second configuration includes the gas turbine engine driving an electrical generator to provide electrical power with the electrical generator connected to the drive shaft. Interchanging the first mobile power unit between the first and second configurations includes changing the pump or the electrical generator for the other of the pump and the electrical generator. 
     In embodiments, operating the first mobile power unit in the second configuration includes providing electrical power to a blender unit, a hydration unit, or a chemical additive unit of a well pad or providing electrical energy to auxiliary equipment of the second mobile power unit. 
     In some embodiments, interchanging the first mobile power unit between the first configuration and the second configuration may include disconnecting the pump form an output flange of the drive shaft, lifting a first skid including the pump from a drive equipment receiver of a transportation platform of the first mobile power unit, installing a second skid including the electrical generator into the drive equipment receiver, and connecting the electrical generator to the output flange of the drive shaft. The first skid may be lifted with a crane or a forklift and may occur at a well pad. 
     In yet another embodiment of the present disclosure, a method of controlling a well pad includes controlling a first mobile power unit, a second mobile power unit, and a blender unit, a hydration unit, or a chemical additive unit with a supervisory control unit. The first mobile power unit includes a gas turbine engine driving an electrical generator. The second mobile power unit includes a gas turbine engine driving a hydraulic fracturing pump. The blender unit, hydration unit, or chemical additive unit receives electrical power from the first mobile power unit. 
     To the extent consistent, any of the embodiments or aspects described herein may be used in conjunction with any or all of the other embodiments or aspects described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the embodiments of the present disclosure, are incorporated in and constitute a part of this specification, and together with the detailed description, serve to explain the principles of the embodiments discussed herein. The present disclosure may be more readily described with reference to the accompanying drawings. 
         FIG.  1    is a schematic view of a well pad layout according to an embodiment of the disclosure. 
         FIG.  2    is a table illustrating exemplary power consumption of pumps of a blender unit according to an embodiment of the disclosure. 
         FIG.  3    is a perspective view of a mobile power unit according to an embodiment of the disclosure. 
         FIG.  4    is a schematic view of the mobile power unit of  FIG.  3    driving a fracturing pump according to an embodiment of the disclosure. 
         FIG.  5    is a schematic view of the mobile power unit of  FIG.  3    driving a generator according to an embodiment of the disclosure. 
         FIG.  6    is schematic view of a mobile power unit driving a reciprocating fracturing pump according to an embodiment of the present disclosure. 
         FIG.  7    is schematic view of a mobile power unit driving a reciprocating fracturing pump including a torsional vibration dampener and torque sensor according to an embodiment of the present disclosure. 
         FIG.  8    is schematic view of a mobile power unit driving a generator including a torsional vibration dampener and torque sensor according to an embodiment of the present disclosure. 
         FIG.  9    is an exploded perspective view, with parts separated, of an alternator of an electrical generator of a mobile power unit of  FIG.  8    according to an embodiment of the present disclosure. 
         FIG.  10    is a flow chart of a method of changing drive equipment of a mobile power unit according to an embodiment of the disclosure. 
         FIG.  11    is a flow chart of a method of controlling a well pad according to an embodiment of the disclosure. 
         FIG.  12    is a flow chart of a method of changing drive equipment of a mobile power unit according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will now be described more fully hereinafter with reference to example embodiments thereof with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. These example embodiments are described so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Features from one embodiment or aspect may be combined with features from any other embodiment or aspect in any appropriate combination. For example, any individual or collective features of method aspects or embodiments may be applied to apparatus, product, or component aspects or embodiments and vice versa. The disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification and the appended claims, the singular forms “a,” “an,” “the,” and the like include plural referents unless the context clearly dictates otherwise. In addition, while reference may be made herein to quantitative measures, values, geometric relationships or the like, unless otherwise stated, any one or more if not all of these may be absolute or approximate to account for acceptable variations that may occur, such as those due to manufacturing or engineering tolerances or the like. 
     Embodiments of the present disclosure are directed to mobile power units and associated methods that may include interchangeable drive equipment. Specifically, mobile power units may include an engine that is coupled to drive equipment such that the drive equipment is driven by the engine. The drive equipment may be a hydraulic fracturing pump or an electrical generator that is interchangeable in the field to allow for a quick changeover between providing high pressure fluid with the fracturing pump and providing electrical power with the electrical generator or vice versa depending on the demands of the well pad. 
       FIG.  1    illustrates an exemplary well pad layout  1000  that is provided in accordance with an embodiment of the present disclosure. The well pad layout  1000  includes a plurality of mobile power units  100  arranged around a wellhead  10  to supply the wellhead  10  with high-pressure fracturing fluids and recover oil and/or gas from the wellhead  10  as will be understood by those skilled in the art. As shown, some of the mobile power units  100 , e.g., mobile power units  100   a , drive a hydraulic fracturing pump  200  that provides high pressure fluid to a manifold  20  such that the high pressure fluid is provided to the wellhead  10 . 
     Additionally, some of the mobile power units  100 , e.g., mobile power units  100   b , drive an electrical generator  300  that provides electrical power to the well pad layout  1000 . For example, the well pad layout  1000  may include auxiliary or backside equipment  400 , as will be understood by those skilled in the art, that requires electrical power to provide fluids to the manifold  20  or the wellhead  10 . Specifically, the backside equipment  400  of the well pad layout  100 , for example, may include a blender unit  410 , a hydration unit  420 , or a chemical additive unit  430 . Each of the units  410 ,  420 ,  430  may be supplied electrical power or electrified such that pumps and other equipment of the units  410 ,  420 ,  430  run on the electrical power. Traditionally, blender units, hydration units, and chemical additive units require horsepower provided by diesel deck engines or small diesel generators. The diesel deck engines and generators may include gearboxes, transmissions, and hydraulic circuits that each require maintenance and may cause failures or breakdowns of the respective unit  410 ,  420 ,  430 . Electrifying the units  410 ,  420 ,  430  by replacing the diesel deck engines, gearboxes, transmissions, and hydraulic circuits with electrical motors may increase in-service time, reduce running costs, decrease maintenance, and decrease emissions of the units  410 ,  420 ,  430 . In addition, electrifying the units  410 ,  420 ,  430  may allow the units  410 ,  420 ,  430  of the auxiliary or backside equipment to meet tier 4 emissions standards. 
     As also shown in  FIG.  2   , in an embodiment, the electrical power requirements of the units  410 ,  420 ,  430  may be calculated for a wellhead, e.g., wellhead  10 , having a maximum anticipated flow rate of 125 barrels per minute (BPM). For example, if pumps of a blender unit  410  are to be electrified, the electrical power demands of the pumps of the blender unit  410  may be calculated based on a maximum anticipated flow rate of the well pad or the fracturing site. Given the maximum anticipated flow rate of 125 BPM, the table of  FIG.  2    illustrates exemplary calculations of the power demands of pumps of the blender unit  410 . As shown, the blender unit  410  may include a suction pump  412 , a discharge pump  414 , and multiple chemical pumps  416 . The chemical pumps  416  may be included on the blender unit  410  or the chemical additive unit  430 . The maximum flow rate of 125 BPM converts to a maximum flow rate of 5250 gallons per minute (GPM) through the blender unit  410 . With such a flow rate, a suction pump  412  of the blender unit  410  may operate at 1250 revolutions per minute (RPM) with an output pressure of 30 pounds per square inch (psi) such that with an eighty percent efficiency of the suction pump  412 , the suction pump  412  may be sized as a 115 horsepower electrical pump. Such a 115 horsepower pump, for example, may have an electrical draw of 86 kilowatts (kW) as will be understood by those skilled in the art. Given a motor efficiency of eighty percent, however, an electrical driving motor for the suction pump  412  may have an electrical draw of 110 kW. Repeating this calculation for the discharge pump  414  results in an electrical draw of 750 kW for the motor driving the discharge pump  414 . Similarly, the chemical pumps  416  may have an electrical draw of 1 kW. In addition, the blender unit  410  also may include other auxiliary components that require electrical power including, but not limited to, sand augers, air compressors, and PLC controllers. The power requirements for these auxiliary components of the blender unit  410  may require 250 kW of electrical power. Thus, the total electrical power to run the blender unit  410  at the maximum flow rate of 125 BPM is 1,100 kW. This process may be repeated for a hydration unit  420  which may have an electrical power requirement of 690 kW. Thus, for example, the total electrical requirement to run the units  410 ,  420 ,  430  may be 1,790 kW as will be understood by those skilled in the art. A single mobile power unit  100  including an engine  120  producing 5100 horsepower may be converted by an electrical generator  300  to produce 3,800 kW of electrical power which would be more than sufficient to provide electrical power for the units  410 ,  420 ,  430  of the auxiliary equipment. 
     In some embodiments, it also may be desirable to electrify the auxiliary equipment of the mobile power units  100 , e.g., mobile power units  100   a . The auxiliary equipment of the mobile power units  100   a , for example, may include, but not be limited to, fuel pumps, cooling pumps, oil/lubrication pumps, cooling fans, and controllers as understood by those skilled in the art. The electrical power requirements for the auxiliary equipment of the mobile power unit may be 270 kW. As a well pad layout, e.g., well pad layout  1000 , may include eight mobile power units  100   a  driving pumps, and the total electrical power requirement for electrifying the auxiliary equipment of the mobile power units  100  of the well pad layout  1000  collectively may be 2,160 kW. 
     If it is desired to electrify the units  410 ,  420 ,  430  and the auxiliary equipment of the mobile power units  100   b , the total electrical power requirement of the well pad layout  1000  may be the sum of the 1,790 kW for the units  410 ,  420 ,  430  and the 2,160 kW for electrifying the auxiliary equipment of eight mobile power units  100   a  such that the total electrical power requirement for the well pad layout  1000  may be 3,950 kW. This electrical power requirement may be beyond the capability of a single mobile power unit  100   b  driving an electrical generator  300 . As such, were the auxiliary equipment of the mobile power units  100   a  also electrified, at least two mobile power units  100   b  driving electrical generators  300  would be required. Additionally, a third mobile power unit  100   b  driving an electrical generator  300  may be desired for redundancy sake. The third mobile power unit  100   b  driving an electrical generator  300  may allow for maintenance and downtime on one of the mobile power units  100   b  driving electrical generators  300  or be available as an extra mobile power unit  100   a  as the drive equipment, e.g., the pump  200  or electrical generator  300 , is and field changeable as detailed below. 
     The well pad layout  1000  may include a supervisory control unit  30  that monitors and controls operation of the mobile power units  100   a  driving fracturing pumps  200 , the mobile power units  100   b  driving electrical generators  300 , and the units  410 ,  420 ,  430 . The supervisory control unit  30  may be a mobile control unit in the form of a trailer or a van, as appreciated by those skilled in the art. In some embodiments, the supervisory control unit  30  receives electrical power from the mobile power units  100   b.    
       FIG.  3    illustrates an exemplary mobile power unit  100  that is provided in accordance with an embodiment of the present disclosure. As noted above, the mobile power units  100  detailed herein include a gas turbine engine  120  that provides mechanical horsepower to drive equipment in the form of a hydraulic fracturing pump  200  or an electrical generator  300 . As described in greater detail below, the hydraulic fracturing pump  200  and the electrical generator  300  are designed as modular components that may be removed and replaced with another pump  200  or generator  300  without modifying the remainder of the mobile power unit  100 . Such a modular design may allow for a single mobile power unit  100  to drive a pump  200  and then be changed over to drive an electrical generator  300 , or vice versa, depending on the demands of the well pad. 
     The exemplary mobile power unit  100   a  of  FIG.  3    includes transportation platform  110 , an engine  120 , and a hydraulic fracturing pump  200 . The transportation platform  110  is shown as a single trailer with the entire mobile power unit  100  and components thereof mounted or installed thereto. For example, it may be advantageous to have the entire mobile power unit  100  mounted to a single trailer such that setup and startup of the mobile power unit  100  does not require onsite assembly of the mobile power unit  100 . In addition, mounting the entire mobile power unit  100  to a single trailer may decrease a footprint of the mobile power unit  100 . The transportation platform  110  may be a trailer that may be pulled by a tractor (not shown) on and off public highways as will be understood by those skilled in the art. In some embodiments, the transportation platform may include more than one trailer. 
     The engine  120  is mounted to the transportation platform  110  and may be any suitable engine including, but not limited to, an internal combustion engine or a gas turbine engine. The engine  120  may be a dual fuel engine operating on gasoline, natural gas, well gas, field gas, diesel, and/or other suitable fuel. In some embodiments, the engine  120  may be a dual fuel engine operating on a liquid fuel and a gaseous fuel. In certain embodiments, the engine  120  is a dual fuel gas turbine engine that asynchronously operates on diesel fuel, e.g., #2 diesel as will be understood by those skilled in the art, and on a gaseous fuel, e.g., natural gas, well gas, or field gas. In particular embodiments, the engine  120  is a dual fuel, dual shaft gas turbine engine that operates on a liquid fuel such as diesel fuel and a gaseous fuel such as natural gas, well gas, or field gas. 
       FIGS.  4  and  5    illustrate that an embodiment of a mobile power unit  100  that selectively may be provided with either a fracturing pump  200  ( FIG.  4   ) or an electrical generator  300  ( FIG.  5   ) that is driven by the engine  120 . The pump  200  and the electrical generator  300  may be referred to generally as the “drive equipment.” The mobile power unit  100  includes a drive equipment position or receiver  190  that receives and secures the drive equipment to the mobile power unit  100  such that the drive equipment is driven by the engine  120  of the mobile power unit  100 . The mobile power unit  100  may include auxiliary equipment to support the mobile power unit  100 . For example, the engine  120  may include a starter  121  that is used to start the engine  120 . A gearbox  130  may include a gearbox lubrication pump  138  that provides lubrication to the gearbox  130 . The mobile power unit  100  also may include a drive lubrication pump  180  that provides lubrication to drive equipment installed in a drive equipment receiver  190 . The drive equipment receiver  190  may be a recess in an upper surface of the transportation platform  110  that is sized to receive the drive equipment therein. The embodiment of the mobile power unit  100  further may include other auxiliary equipment in the form of cooling or heating fans, controllers, and pumps. The auxiliary equipment of the mobile power unit  100  may be driven by deck engines or may be electrified as detailed herein. 
     The pump  200  and the electrical generator  300  may be secured to a skid  220 ,  320 , as will be understood by those skilled in the art, that provides for a stable base for the pump  200  or the electrical generator  300  and allows for the pump  200  or the electrical generator  300  to be lifted from and installed or mounted within the drive equipment receiver  190  of the mobile power unit  100 . The skid  220 ,  320  may be constructed from a structural steel, e.g., AISI 1018 steel. The skid  220 ,  320  may include alignment features that align the skid  220 ,  320  within the drive equipment receiver  190  such that drive components and/or auxiliary equipment of the pump  200  or the generator  300  are aligned with the components of the mobile power unit  100 , e.g., the engine  120 . The skids  220 ,  320  may include lifting slots  225 ,  325  positioned therein that are sized to be engaged by components of a lifting device, e.g., a fork of a forklift, as would be appreciated by one skilled in the art, such that the respective skid  220 ,  320 , including a pump  220  or generator  300 , to be lifted onto or removed from the drive equipment receiver  190  of the mobile power unit  100 . The skid  220 ,  320  may include auxiliary components that support operation of the respective one of the pump  200  or the electrical generator  300 . 
     In some embodiments, the pump  200  or the electrical generator  300  may include lifting loops  210 ,  310 , respectively, that allow for lifting of the pump  200  or the electrical generator  300  by a crane or other lifting device, as would be appreciated by one skilled in the art, to be lifted onto or removed from the drive equipment receiver  190  of the mobile power unit  100 . The lifting loops  210 ,  310  may be secured to the skids  220 ,  320  or to a body of the pump  200  or the generator  300 . Having both the lifting loops  210 ,  310  and the lifting slots  215 ,  315  allow for removal and installation of the pump  200  or the electrical generator  300  in a field or in a shop environment. 
       FIG.  6    schematically illustrates an embodiment of the mobile power unit  100  with an engine  120  connected to a pump  200  that is installed in the drive equipment receiver  190  of the mobile power unit  100 . The engine  120  includes a power end  126  that directly drives an engine output shaft  128 . The engine output shaft  128  is coupled to a reduction gearbox  130  such that a speed of rotation of the engine output shaft  128  is stepped down to a speed of rotation of a gearbox output shaft  134  of the gearbox  130  that is suitable for a hydraulic fracturing pump, e.g., pump  200 . For example, a speed of rotation of the engine output shaft  128  of the engine  120  may be 16,500 RPM and a speed of rotation of the gearbox output shaft  134  of the gearbox  130  that is suitable for the pump  200  may be 1500 RPM such that a ratio of the reduction gearbox  130  is an  11 : 1  reduction. The reduction gearbox  130 , for example, in some embodiments, may have a ratio in a range of 5:1 to 20:1 depending on the specifications of the engine  120  and the pump  200  to be driven by the engine  120 . It will be appreciated that as the rotation speed of the engine output shaft  128  is stepped down to the rotation speed of the gearbox output shaft  134  at the ratio of the gearbox  130  that the torque of the output shaft  128  is stepped up to torque of the output shaft  134  at the inverse of the ratio, e.g., 1:11 step up for a 11:1 step down. 
     The gearbox output shaft  134  of gearbox  130  includes an output flange  136  that is coupled to an input flange  142  of a drive shaft  140  such that the drive shaft  140  is directly driven by the engine  120  via the gearbox  130 . The drive shaft  140  includes an output flange  144  that releasably and selectively may be connected to an input shaft  250  of the pump  200  such that the pump  200  is directly driven by the engine  120  via the drive shaft  140 . 
       FIG.  7    schematically illustrates an embodiment of a mobile power unit  100  with the engine  120  connected to the pump  200  that is installed in the drive equipment receiver  190  of the mobile power unit  100  such that the pump  200  is driven by the engine  120  via the drive shaft  140  in a manner as detailed above. The drive shaft  140  includes a torsional vibration damper (TVD) system  150  and a torque sensor  158 , as will be understood by those skilled in the art. The TVD system  150  may dampen torque variations from the engine  120  to the pump  200  and/or may dampen reaction torque variations from the pump  200  to the engine  120 . The TVD system  150  may prevent or reduce torque variations experienced by the engine  120 , the gearbox  130 , the drive shaft  140 , and/or the pump  200  such that a service interval or the service life of the engine  120 , the gearbox  130 , the drive shaft  140 , and/or the pump  200  may be extended. The drive shaft  140  also may include one or more torque sensors  160  installed thereon that measure a torque of the drive shaft  140 . The torque sensors  160  may provide a signal to one or more controllers of the mobile power unit  100 , e.g., a controller of the engine  120  or a controller of the pump  200 . The controllers of the mobile power unit  100  or the torque sensors  160  may provide a signal to the supervisory control unit  30  ( FIG.  1   ) indicative of the torque of the drive shaft  140 . The torque of the drive shaft  140  may be used in one or more control algorithms for the engine  120 . 
       FIG.  8    schematically illustrates an embodiment of a mobile power unit  100  with the engine  120  connected to an electrical generator  300  that is installed in the drive equipment receiver  190  of the mobile power unit  100  such that the electrical generator  300  is driven by the engine  120  via the drive shaft  140 . Specifically, the generator  300  includes an alternator  330  that rotates to generate alternating current (AC) electrical power which is suitable for the units  410 ,  420 ,  430  ( FIG.  1   ), the auxiliary equipment of the mobile power units  100   a , or the supervisory control unit  30  ( FIG.  1   ). The speed of rotation of the alternator  330  that is suitable for generation of electrical power depends on the number of poles of the alternator  330  and the frequency of the AC power as represented by the following equation: 
             f   =       P   ·   N       1   ⁢   2   ⁢   0             
where f is the output frequency in hertz (Hz), P is the number of poles, and N is the RPM of the alternator. As most electrical equipment in the United States operates at a frequency of 60 hertz (Hz), the rotational speed of the alternator  330  to provide AC power 60 Hz, for example, may be 3600 RPM for a 2-pole configuration and 1800 RPM for a 4-pole configuration. Those skilled in the art recognize that other speeds may be suitable for rotation of the alternator  330  depending on the desired frequency of the AC power, e.g., 50 Hz or 60 Hz, or the number of poles of the alternator, e.g., 2, 4, 6, 8, 10 poles.
 
     The electrical generator  300  includes an input shaft  350  that releasably couples or otherwise connects to the output flange  144  of the drive shaft  140 . As the electrical generator  300  may be a selective replacement for the pump  200 , and the gearbox  130  has a fixed reduction ratio in a range of 5:1 to 20:1, e.g., 11:1, based on the speed requirements of the pump  200 , the drive shaft  140  has a maximum speed of rotation of 1500 RPM. This results in the speed of rotation of the drive shaft  140  being less that what is required by the alternator  330  of the electrical generator  300  as detailed above with respect to a 2-pole or 4-pole configuration of the alternator  330 . For this reason, the electrical generator  300  includes a step up generator gearbox  360  to increase the speed of rotation of the input shaft  350  to a speed of rotation that is suitable for the electrical generator  300 . The ratio of the generator gearbox  360  ratio is set based on keeping the engine running at as high of a load and speed as possible and the number of poles of the electrical generator  300 . As the input speed of the drive shaft  140  has a maximum speed of rotation of 1500 RPM, the generator gearbox  310  may have a ratio of 1:2.5 which allows for the speed of rotation of the electrical generator  300  to be 1800 RPM or 3600 RPM depending on the number of poles of the generator  300  installed on the mobile power unit  100 . However, other ratios in a range of 1:1.25 to 1:5 may be used based on a desired speed of rotation of the electrical generator  300  as will be understood by those skilled in the art. Those skilled in the art appreciate that the speed of the engine  120  may be controlled by the supervisory control unit  30 . Including a generator gearbox  360  which may allow for the electrical generator  300  selectively to be changed with the pump  200  by releasably coupling or connecting to the drive shaft  140  without changing the ratio of the reduction gearbox  130  of the engine  120 . By not requiring the changing of the reduction gearbox  130  or requiring the reduction gearbox  130  to have multiple settings, one for the pump  200  and one for the generator  300 , the efficiency of the reduction gearbox  130  may be increased and/or the complexity of changing the drive equipment may be simplified. 
     The alternator  330  of the electrical generator  300  is designed and sized based on the electrical demands of the fracturing fleet, e.g., the power demands of the well pad layout. As detailed above, when the alternator  330  is providing electrical power for the units  410 ,  420 ,  430  ( FIG.  1   ), the electrical power requirement is 1,790 kW, and when the engine  120  is a 5,100 horsepower engine, the engine  120  may be capable of providing 3,800 kW of energy. Thus, the alternator  330  should be sized to generate at least 1,800 kW and to be capable of generating 3,800 kW when required. For example, when auxiliary equipment of the mobile power units  100   a  also are provided with electrical power from one or more generators  300 . 
       FIG.  9    illustrates a construction of an exemplary alternator  330  in an exploded perspective view as provided in accordance with embodiments of this disclosure. The alternator  330  may be a permanent magnet alternator and more specifically, an AC synchronous alternator in which the stator and the rotor spin at the same speed. Such an alternator may have increased efficiency when compared to other alternators and does not require electrical power to the rotor to generate electrical power. As shown, the alternator  330  includes a rotor mount  332 , a solid rotor  334 , a stator  336 , a field coil  338 , and a housing  440 . The rotor mount  332  is attached to an output shaft of the generator gearbox  360  ( FIG.  8   ) such that the rotor mount  332  rotates at the output speed of the generator gearbox  360 . The rotor mount  332  may include a blower  333  that includes vanes to direct fluid flow within the alternator  330  to cool internal components of the alternator  330 . The rotor  334  is mounted to the rotor mount  332  such that the rotor  334  is rotatably fixed to the rotor mount  332 . The rotor  334  may be a solid rotor and includes permanent magnets  335  mounted therein. The rotor  334  may include 12 permanent magnets  335  which may be NdFeB magnets, for example, as will be understood by those skilled in the art. The stator  336  is mounted to the rotor mount  332  within the rotor  334  such that the stator  336  rotates in concert with the rotor  334 . The stator  336  may be a 6-phase stator, for example. The field coil  338  is mounted to the housing  340  about the stator  336  such that as the rotor  334  and the stator  336  rotate, AC power is transferred to terminals  342  of the housing  340 . The housing  340  is disposed over the rotor mount  332 , the solid rotor  334 , the stator  336 , and the field coil  338  such that the rotor mount  332 , the solid rotor  334 , the stator  336 , and the field coil  338  rotate within the housing  340 . 
     As shown in  FIG.  5   , embodiments of the alternator  330  also may require a cooling system  370  to cool internal components of the alternator  330 . In some embodiments, the cooling system  370  includes a coolant pump  372  that circulates fluid through the alternator  330  to cool internal components thereof. The fluid may be air or glycol water, as will be understood by those skilled in the art. In certain embodiments, the cooling system  370  of the alternator  330  is self-sufficient such that the cooling system  370  is powered by the alternator  330  when the alternator  330  generates electrical power. In particular embodiments, the cooling system  370  of the alternator  330  requires external power to power the cooling system  370 . In such embodiments, the cooling system  370  may be powered by a lubrication system  180  of the mobile power unit  100  ( FIG.  4   ) that is configured to cool the pump  200  when the pump  200  is installed on the mobile power unit  100 . The lubrication system  180  may include a changeover valve to be compatible with the cooling pump  372  of the generator  300 . The cooling system  370  may require a coolant storage tank  374  which may be mounted to the skid  320  or the alternator  330  such that the cooling system  370  and the coolant storage tank is part of the electrical generator  300  and is installed with the electrical generator  300 . 
       FIG.  10    illustrates a method  1001  of changing a power device of a mobile power unit in accordance with exemplary embodiments of the present disclosure with reference to the mobile power unit of  FIGS.  3 - 5   . As described in greater detail below, the method  1001  includes a mobile power unit  100  driving a pump  200  in a first configuration (Step  1010 ), an electrical generator  300  in a second configuration (Step  1020 ), and changing the pump  200  or the electrical generator  300  for the other of the pump  200  or the electrical generator  300  (Step  1100 ). The method  1001  may include receiving a signal indicative of an electrical demand, an electrical supply, a fluid requirement, or a fluid supply of a well pad site. Changing the mobile power unit  100  between the first configuration and the second configuration may occur at least in part as a result of analyzing or determining that the electrical demand of the well pad site is greater than the electrical supply, that a fluid supply is greater than a fluid requirement of the well pad site, that an electrical supply is greater than an electrical demand of the well pad site, or that the fluid requirement of the well pad site is greater than the fluid supply. 
     In the first configuration, a gas turbine engine  120  of the mobile power unit  100  drives the pump  200  to provide high pressure fluid (Step  1010 ). The pump  200  is connected to a drive shaft  140  of the mobile power unit  100 . The drive shaft  140  may have a maximum speed of rotation in a range of 1000 RPM to 1700 RPM. Operating the mobile power unit  100  in the first configuration may include operating the gas turbine engine  120  on field gas, for example. 
     The method  1001  may include selectively interchanging the pump  200  of the mobile power unit  100  for the electrical generator  300  (Step  1100 ). Interchanging the pump  200  for the electrical generator  300  may include disconnecting the pump  200  from an output flange  144  of the drive shaft  140  (Step  1110 ) before lifting a skid  220  that includes the pump  200  from a drive equipment receiver  190  of a transportation platform  110  of the mobile power unit  100  (Step  1120 ). Lifting the skid  220  may include lifting the skid  200  with a crane or a forklift. With the pump  200  removed, a skid  320  including the electrical generator  300  is installed into the drive equipment receiver  190  of the transportation platform  110  (Step  1130 ). With the skid  320  installed in the drive equipment receiver  190 , the electrical generator  300  is connected to the output flange  144  of the drive shaft  140  (Step  1140 ). Interchanging the pump  200  for the electrical generator  300  may occur at a well pad or at a plant. 
     With the electrical generator  300  connected to the output flange  144 , the mobile power unit  100  is operated in a second configuration in which the gas turbine engine  120  drives the electrical generator  300  (Step  1020 ), e.g., instead of the pump  200 , to provide electrical power. In the second configuration, the mobile power unit  100  may provide electrical power to a blender unit  410 , a hydration unit  420 , or a chemical additive unit  430  of a well pad  1000 . Additionally or alternatively, in the second configuration, the mobile power unit  100  may provide electrical power to auxiliary equipment of another mobile power unit  100  which includes a gas turbine engine  120  driving a hydraulic fracturing pump  200 . Operating the mobile power unit  100  in the second configuration may include operating the gas turbine engine  120  on field gas. 
     In the second configuration, the method  1001  may include monitoring and controlling the electrical generator of the first mobile power unit  100  with a supervisory control unit  30  ( FIG.  1   ). As described in greater detail below with respect to method  1200 , the supervisory control unit  30  may monitor and control delivery of a high pressure fluid of a second mobile power unit having a gas turbine engine driving a pump simultaneously with monitoring and controlling the first mobile power unit in the second configuration. 
     The method  1001  may include selectively interchanging the electrical generator  300  of the mobile power unit  100  for the pump  200  (Step  1150 ). Interchanging the electrical generator  300  for the pump  200  may include disconnecting the electrical generator  300  from the output flange  144  of the drive shaft  140  (Step  1160 ) before lifting a skid  220  that includes the electrical generator  300  from a drive equipment receiver  190  of a transportation platform  110  of the mobile power unit  100  (Step  1170 ). Lifting the skid  220  may include lifting the skid  200  with a crane or a forklift. With the electrical generator  300  removed, a skid  220  including the pump  200  is installed into the drive equipment receiver  190  of the transportation platform  110  (Step  1180 ). With the skid  220  installed in the drive equipment receiver  190 , the pump  200  is connected to the output flange  144  of the drive shaft  140  (Step  1190 ). Interchanging the electrical generator  300  for the pump  200  may occur at a well pad or at a plant. 
       FIG.  11    shows a method  1200  of controlling a well pad in accordance with exemplary embodiments of the present disclosure with reference to the well pad  1000  of  FIG.  1   . The method  1200  includes operating a supervisory control unit  30  to control a first mobile power unit  100 , to control a second mobile power unit  100 , and to control a blender unit  410 , a hydration unit  420 , or a chemical additive unit  430 . 
     Operating the supervisory control unit  30  includes receiving operating parameters of the well pad  1000  at the supervisory control unit  30  ( 1210 ). In response to receiving operating parameters, the supervisor control unit  30  provides control signals to the first mobile power unit  100  to control the first mobile power unit  100  (Step  1230 ), provides control signals to the second mobile power unit  100  (Step  1250 ), and provides control signals to the blender unit  410 , the hydration unit  420 , or the chemical additive unit  430  (Step  1270 ). 
     The supervisory control unit  30  may receive feedback signals from first mobile power unit  100  (Step  1220 ) and may modify control signals provided to the first mobile power unit  100  in response to the feedback signals (Step  1240 ). For example, the supervisory control unit  30  may change a supply of air or fuel to the gas turbine engine  120  such that the gas turbine engine  120  changes power delivery to the electrical generator  300  based on energy demands of the well pad  100 . The supervisory control unit  30  may calculate energy demands of the well pad  1000  by monitoring or receiving feedback from the first mobile power unit  100 , the second mobile power unit  100 , and a blender unit  410 , a hydration unit  420 , or a chemical additive unit  430 . In some embodiments, the method  1200  may include the first mobile power unit  100  providing power to a supervisory control vehicle that includes the supervisory control unit  30 . 
     The supervisory control unit  30  may receive feedback signals from the second mobile power unit  100  (Step  1220 ) and may modify control signals provided to the second mobile power unit  100  in response to the feedback signals (Step  1260 ). For example, the supervisory control unit  30  may change the supply of air or fuel to the gas turbine engine  120  of the second mobile power unit  100  to change an amount or pressure of a high pressure fluid from the pump  200  in response to the feedback signals of the second mobile power unit  100 . 
     The supervisory control unit  30  may receive feedback signals from the blender unit  410 , the hydration unit  420 , or the chemical additive unit  430  (Step  1220 ) and may modify control signals provided to the units  410 ,  420 , or  430  based on the feedback signals (Step  1280 ). For example, the supervisory control unit  30  may change an amount of fluid provided to the pump  200  by a respective one units  410 ,  420 , or  430 . The supervisory control unit  30  may control the units  410 ,  420 ,  430  by changing a supply or electrical power from the electrical generator  300  of the first mobile power unit  100 . 
       FIG.  12    illustrates a method  1300  of changing drive equipment of a mobile power unit in accordance with exemplary embodiments of the present disclosure with reference to the mobile power unit of  FIGS.  3 - 5   . The method  1300  includes operating a mobile power unit  100  in a first configuration (Step  1310 ), receiving one or more signals indicative of an electrical demand or fluid requirements of a well pad site (Step  1320 ), determining that the electrical demand of the well pad site  1000  is greater than an electrical supply or that a fluid capacity is greater than the fluid requirements (Step  1330 ), and interchanging the first mobile power unit  100  from a first configuration to a second configuration (Step  1340 ). 
     Operating the first mobile power unit  100  in the first configuration (Step  1310 ) includes the first mobile power unit  100  driving a pump  200  to provide high pressure fluid to the well pad site  1000 . The mobile power unit  100  includes a gas turbine engine  120  that drives the pump  200  to provide the high pressure fluid. The pump  200  is connected to a drive shaft  140  of the mobile power unit  100  which has a reduction gearbox  130  such that the drive shaft  140  may have a maximum speed of rotation in a range of 1000 RPM to 1700 RPM. Operating the mobile power unit  100  in the first configuration may include operating the gas turbine engine  120  on field gas, for example. 
     When the first mobile power unit  100  is operating in the first configuration, a supervisory control unit  30  of the well pad site  1000  receives demand signals from equipment of the well pad site  1000  and input from the operators at the well pad site  1000  that are indicative of an electrical demand and fluid requirements of the well pad site  1000  (Step  1320 ). In addition, the supervisory control unit  30  may receive performance signals from equipment of the well pad site  1000  (e.g., mobile power units  100 , pumps  200 , generators  300 , or auxiliary units  410 ,  420 ,  430 ) (Step  1325 ). The supervisory control unit  30  may display the electrical demand and the fluid requirements of the well pad site  1000  and display the current electrical supply and fluid supply of the well pad site  1000  based on the signals received. 
     The operator or the supervisory control unit  30  may compare the electrical demand to the electrical supply or the fluid requirements to the fluid capacity (Step  1330 ). When the operator or the supervisory control unit  30  determines that the electrical demand of the well pad site  1000  is greater than the electrical supply or that the fluid capacity is greater than the fluid requirements, the first mobile power unit  100  may be interchanged from the first configuration to a second configuration (Step  1340 ). The decision to interchange the first mobile power unit  100  may be made to optimize electrical supply or fluid capacity or to allow for maintenance of other mobile power units  100 . When the electrical demand is less than the electrical supply and the fluid capacity is less than the fluid requirements, the first mobile power unit  100  may remain in the first configuration. 
     When the first mobile power unit  100  is interchanged to the second configuration, the pump  200  of the first mobile power unit  100  is changed for an electrical generator  300  (Step  1350 ). In the second configuration, the electrical generator  300  is connected to the drive shaft  140  to produce electrical energy for the well pad site  1000 . The electrical generator  300  includes a generator gearbox  360  to at least partially offset the reduction gearbox  130 . The electrical generator  300  may provide electrical power to auxiliary units such as a blender unit  410 , a hydration unit  420 , or a chemical additive unit  430 . 
     When the first mobile power unit  100  is operating in the second configuration, the supervisory control unit  30  of the well pad site  1000  may continue to receive demand signals from equipment of the well pad site  1000  and input from the operators at the well pad site  1000  that are indicative of an electrical demand and fluid requirements of the well pad site  1000  (Step  1360 ). In addition, the supervisory control unit  30  may receive performance signals from equipment of the well pad site  1000  (e.g., mobile power units  100 , pumps  200 , generators  300 , or auxiliary units  410 ,  420 ,  430 ) (Step  1365 ). The supervisory control unit  30  may display the electrical demand and the fluid requirements of the well pad site  1000  and display the current electrical supply and fluid supply of the well pad site  1000  based on the signals received. 
     The operator or the supervisory control unit  30  may compare the electrical demand to the electrical supply or the fluid requirements to the fluid capacity (Step  1370 ). When the operator or the supervisory control unit  30  determines that the fluid requirements of the well pad site  1000  is greater than the fluid capacity or that the electrical supply is greater than the electrical demand, the first mobile power unit  100  may be interchanged from the first configuration to a second configuration (Step  1380 ). The decision to interchange the first mobile power unit  100  may be made to optimize electrical supply or fluid capacity or to allow for maintenance of other mobile power units  100 . When the fluid requirement is less than the fluid capacity and the electrical supply is less than the electrical demand, the first mobile power unit  100  may remain in the second configuration. 
     When the first mobile power unit  100  is interchanged to the first configuration, the electrical generator  300  of the first mobile power unit  100  is changed for a pump  200  (Step  1390 ). As detailed above, in the first configuration, the pump  200  is connected to the drive shaft  140  to produce fluid capacity for the well pad site  1000 . Interchanging the first mobile power unit  100  between the first configuration and the second configuration may occur at a well pad site  1000 . 
     This is a divisional of U.S. Non-Provisional application Ser. No. 17/377,884, filed Jul. 16, 2021, titled “DRIVE EQUIPMENT AND METHODS FOR MOBILE FRACTURING TRANSPORTATION PLATFORMS,” which is a divisional of U.S. Non-Provisional application Ser. No. 17/301,305, filed Mar. 31, 2021, titled “DRIVE EQUIPMENT AND METHODS FOR MOBILE FRACTURING TRANSPORTATION PLATFORMS,” now U.S. Pat. No. 11,111,768, issued Sep. 7, 2021, which claims priority to and the benefit of, under 35 U.S.C. § 119(e), U.S. Provisional Application No. 62/705,055, filed Jun. 9, 2020, titled “DRIVE EQUIPMENT AND METHODS FOR MOBILE FRACTURING TRANSPORTATION PLATFORMS,” the disclosures of which are incorporated herein by reference in their entireties. 
     The foregoing description of the disclosure illustrates and describes various exemplary embodiments. Various additions, modifications, changes, etc., may be made to the exemplary embodiments without departing from the spirit and scope of the disclosure. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Additionally, the disclosure shows and describes only selected embodiments of the disclosure, but the disclosure is capable of use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein, commensurate with the above teachings, and/or within the skill or knowledge of the relevant art. Furthermore, certain features and characteristics of each embodiment may be selectively interchanged and applied to other illustrated and non-illustrated embodiments of the disclosure.