FIRED PROCESS HEATER WITH A MANIFOLD SUPPORT ASSEMBLY

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The application claims the benefit of and priority to U.S. Provisional Ser. No. 63/730,514 , filed Dec. 11, 2024, and incorporates by reference the provisional application in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to fired heaters that use hot combustion gases to heat a process fluid flowing through tubular coil bundles in the fired heater and, more particularly, to a fired process heater with a manifold support assembly configured to support a radiant coil assembly within a radiant section of the process heater.

2. Description of the Related Art

Fired process heaters are used across multiple industries for high-temperature heating applications, and direct-fired heaters are used extensively in oil refineries, chemical, petrochemical, and other industrial plants to heat fluids within tubes at high temperatures not achievable by other methods. In a fired heater, heat liberated by the combustion of fuel in one or more burners is transferred to fluids contained in tubular coils within an internally insulated enclosure.

The type of heater is normally described by the structural configuration, radiant-tube coil configuration, and burner arrangement. Some examples of structural configurations are cylindrical, box, cabin, and multicell box. Examples of radiant-tube coil configurations include vertical, horizontal, helical, and arbor. Examples of burner arrangements include up-fired, down-fired, and wall-fired. The wall-fired arrangement can be further classified as sidewall, endwall, and multilevel.

FIG. 1 depicts a representative exterior general arrangement for a direct-fired process heater 100 that utilizes an exterior forced draft burner 102 and a forced draft fan 104. The fired process heater 100 includes a radiant section or firebox 106, a convection section 108, and a stack 110. Both the radiant section 106 and the convection section 108 include an exterior heater casing 112 and a refractory lining 120 to minimize setting losses and protect the casing 112. An external convection-radiant crossover bundle 116 fluidly connects a tubular radiant coil assembly 114 in the radiant section 106 and a tubular convection coil assembly 118 in the convection section 108. During the heater process, process fluid from the convection coil assembly 118 in the convection section 108 flows to the radiant coil assembly 114 in the radiant section 106 for a combination of radiation, convection, and conduction heat transfer from the burner 102 flames to the process fluid within the radiant coil assembly 114 and the convection coil assembly 118.

The fired process heater 100 requires mechanical support to stabilize internal process tubes while allowing appropriate expansion and contraction. Per industry standard practice, the mechanical support is designed to withstand the loading from the tubes at the internal temperature of the heater without the aid of any external cooling. As shown in FIGS. 2, 3A, and 3B, the radiant coil assembly 114 is supported by traditional tube supports 122, such as castings or plates, mounted to the interior of the heater casing 112 using tube support clips 124. This conventional design provides no external cooling to the tube supports 122, which must withstand the weight of the radiant coil assembly 114 at the operating temperature present in the firebox of the heater 100, which may reach upward of 2200° F. entering the creep range for most metals. As such, conventional process tube supports 122 are designed with a finite lifespan, and higher alloy materials are used to attempt to maintain safety as the supports 122 are continually being degraded by heat. If the internal temperature extends into the creep range of the metallurgy used for the process tube supports, the supports 122 will experience creep, lose integrity over time within the high-temperature environment, and ultimately fail. This loss of integrity allows the radiant coil assembly 114 to sag and potentially over-stress the terminals and/or enter the path of the internal flame from the burner 102, causing flame impingement. If the radiant coil assembly 114 ultimately cracks, the flammable process fluid may be released onto a direct flame, presenting a serious safety hazard.

SUMMARY OF THE INVENTION

Therefore, it is desirable to provide a fired process heater with a manifold support assembly configured to support the radiant coil assembly within the radiant section of the process heater. The manifold support assembly mitigates sag and loss of integrity of the radiant coil assembly during the high-temperature operating environment. The manifold support assembly extends the life of the radiant coil assembly within the fired process heater.

In general, in a first aspect, the invention relates to a fired process heater for transferring heat energy to a process fluid. The fired process heater has a radiant coil assembly with a radiant coil bundle inlet, a radiant coil bundle outlet, and a radiant flow path through a radiant coil bundle intermediate of the radiant coil bundle inlet and the radiant coil bundle outlet. A manifold support assembly is fluidly connected to and configured to support the radiant coil assembly, and the process fluid flows through both the radiant coil assembly and the manifold support assembly.

In an embodiment, the manifold support assembly has a manifold support inlet, a manifold support outlet, and a manifold support flow path in fluid communication with a manifold support coil bundle intermediate of the manifold support inlet and the manifold support outlet.

In an embodiment, the radiant coil assembly is positioned upstream of the manifold support assembly.

In an embodiment, the radiant coil bundle inlet is fluidly connected to a convection coil bundle outlet of a convection coil assembly, and the radiant coil bundle outlet is fluidly connected to the manifold support inlet of the manifold support assembly.

In an embodiment, the fired process heater also includes a convection-radiant crossover bundle in fluid communication with the convection coil assembly and the radiant coil assembly.

In an embodiment, the manifold support assembly is positioned upstream of the radiant coil assembly.

In an embodiment, the manifold support outlet of the manifold support assembly is fluidly connected to a convection coil bundle inlet of a convection coil assembly, and a convection coil bundle outlet of the convection coil assembly is fluidly connected to the radiant coil bundle inlet of the radiant coil assembly.

In an embodiment, the fired process heater includes a convection-radiant crossover bundle in fluid communication with the convection coil assembly and the radiant coil assembly.

In an embodiment, the fired process heater includes a manifold support assembly-convection crossover bundle in fluid communication with the manifold support assembly and the convection coil assembly.

In an embodiment, the manifold support coil bundle includes a generally U-shaped manifold pipe fluidly connected to the manifold support inlet and the manifold support outlet.

In an embodiment, the manifold support coil bundle includes a first horizontal pipe configured parallel to a second horizontal pipe. The radiant coil bundle is supported by the first horizontal pipe and the second horizontal pipe.

In an embodiment, the manifold support assembly is constructed from a metal alloy material, such as carbon steel.

In general, in a second aspect, the invention relates to a fired heater having a convection coil assembly with a convection coil bundle inlet, a convection coil bundle outlet, and a convection flow path through a convection coil bundle intermediate of the convection coil bundle inlet and the convection coil bundle outlet. The heater also has a radiant coil assembly with a radiant coil bundle inlet, a radiant coil bundle outlet, and a radiant flow path through a radiant coil bundle intermediate of the radiant coil bundle inlet and the radiant coil bundle outlet. The radiant coil bundle inlet is fluidly connected to the convection coil bundle outlet of the convection coil assembly. In addition, a manifold support assembly is fluidly connected to, positioned downstream of, and configured to support the radiant coil assembly. The manifold support assembly has a manifold support inlet, a manifold support outlet, and a manifold support flow path in fluid communication with a manifold support coil bundle intermediate of the manifold support inlet and the manifold support outlet.

In an embodiment, the manifold support inlet of the manifold support assembly is fluidly connected to a radiant coil bundle outlet manifold.

In an embodiment, the manifold support coil bundle includes a generally U-shaped manifold pipe fluidly connected to the manifold support inlet and the manifold support outlet.

In an embodiment, the manifold support coil bundle includes a first horizontal pipe and a second horizontal pipe configured parallel to the first horizontal pipe. The radiant coil bundle is supported by the first horizontal pipe and the second horizontal pipe.

In general, in a third aspect, the invention relates to a fired heater having a convection coil assembly with a convection coil bundle inlet, a convection coil bundle outlet, and a convection flow path through a convection coil bundle intermediate of the convection coil bundle inlet and the convection coil bundle outlet. The heater also has a radiant coil assembly with a radiant coil bundle inlet, a radiant coil bundle outlet, and a radiant flow path through a radiant coil bundle intermediate of the radiant coil bundle inlet and the radiant coil bundle outlet. The radiant coil bundle inlet is fluidly connected to the convection coil bundle outlet of the convection coil assembly. In addition, a manifold support assembly is fluidly connected to, positioned upstream of, and configured to support the radiant coil assembly. The manifold support assembly has a manifold support inlet, a manifold support outlet, and a manifold support flow path in fluid communication with a manifold support coil bundle intermediate of the manifold support inlet and the manifold support outlet.

In an embodiment, the convection coil bundle inlet is fluidly connected to the manifold support outlet of the manifold support assembly.

In an embodiment, the fired heater includes a manifold support assembly-convection crossover bundle in fluid communication with the manifold support assembly and the convection coil assembly.

In an embodiment, the manifold support coil bundle includes a generally U-shaped manifold pipe fluidly connected to the manifold support inlet and the manifold support outlet.

In an embodiment, the manifold support coil bundle includes a first horizontal pipe and a second horizontal pipe configured parallel to the first horizontal pipe. The radiant coil bundle is supported by the first horizontal pipe and the second horizontal pipe.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects and advantages of this invention may be more clearly seen when viewed in conjunction with the accompanying drawing wherein:

FIG. 1 is a side elevation general arrangement view of a direct-fired process heater.

FIG. 2 is a side elevation cross-section view of a direct-fired process heater with a radiant coil assembly supported by traditional tube supports within the radiant section of the heater.

FIG. 3A is a side elevation view of a tube support and tube support clips for the radiant coil assembly shown in FIG. 2.

FIG. 3B is a front elevation view of the tube support and the tube support clips shown in FIG. 3A.

FIGS. 4A and 4B are perspective views of an example of a tubular coil assembly for a fired heater with a radiant coil assembly supported within a radiant section by a manifold support assembly in accordance with an exemplary embodiment of the invention.

FIG. 5 is a plan view of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 4.

FIG. 6 is a side elevation view of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 4.

FIG. 7 is a front elevation of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 4.

FIG. 8 is a rear elevation view of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 4.

FIG. 9 is a flowchart depicting an example of a process for transferring heat energy to a process fluid using the tubular coil assembly having the manifold support assembly shown in FIGS. 4 through 8 in accordance with an exemplary embodiment of the invention.

FIG. 10 is a perspective view of another example of a tubular coil assembly for a fired heater with a radiant coil assembly supported within a radiant section by a manifold support assembly in accordance with an exemplary embodiment of the invention.

FIG. 11 is a plan view of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 10.

FIG. 12 is a side elevation view of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 10.

FIG. 13 is a front elevation view of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 10.

FIG. 14 is a rear elevation of the tubular coil assembly with the radiant coil assembly supported by the manifold support assembly shown in FIG. 10.

FIG. 15 is a flowchart depicting an example of a process for transferring heat energy to a process fluid using the tubular coil assembly having the manifold support assembly shown in FIGS. 10 through 14 in accordance with another exemplary embodiment of the invention.

DETAILED DESCRIPTION

While this invention is susceptible to embodiment in many different forms, there are shown in the drawings and will be described hereinafter in detail some specific embodiments of the invention. It should be understood, however, that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments so described.

A fired process heater is disclosed as having a tubular coil assembly with a radiant coil assembly supported within a radiant section by a manifold support assembly. The fired process heater is configured to transfer heat energy to a process fluid, which may be a single-phase, liquid or vapor, or mixed-phase vapor-liquid stream. Suitable process fluids include, but are not limited to, a thermal fluid (hot oil), glycol mixture, or vapor. Unlike conventional designs, the disclosed fired process heater flows the process fluid through the manifold support assembly to provide cooling to the manifold support assembly through the heat transfer process. The manifold support assembly mitigates sag and loss of integrity of the radiant coil assembly during the high-temperature operating environment and extends the life of the radiant coil assembly within the fired process heater.

Referring now to the figures of the drawings, wherein like numerals of reference designate like elements throughout the several views, similar to the conventional fired heater design shown in FIG. 1, a direct-fired process heater 100 has one or more exterior forced draft burners 102 to introduce fuel and air into the heater 100 at a desired velocity, turbulence, and concentration to establish and maintain proper ignition and combustion and a forced draft fan 104 to induce combustion air to the burner 102. The fired process heater 100 includes a radiant section or firebox 106 for radiant heat transfer, a convection section 108 for convection heat transfer, and a stack 110 to discharge flue gas to the atmosphere. Both the radiant section 106 and the convection section 108 include an exterior heater casing 112 and a refractory lining 120 that surrounds the firebox 106.

The fired heater 100 has a tubular coil assembly 200 with multiple process tubes arranged in single or multiple fluid passes (circuits). The coil assembly 200 includes a radiant coil assembly 202 within the radiant section 106 and a convection coil assembly 238 within the convection section 108 of the heater 100. The convection coil assembly 238 has a convection coil bundle 342 with a convection coil bundle inlet 344 and a convection coil bundle outlet 346. When the fired heater 100 contains more than one fluid pass (circuit), the convection coil bundle inlet 344 can include an inlet manifold 348 to evenly distribute the process fluids to the individual flow passes of the convection coil bundle 342. As illustrated, the convection coil bundle 342 is arranged as staggered rows to maximize convective heat transfer to the process fluid; however, the convection coil bundle 342 could be arranged in other configurations, such as in-line rows.

A convection-radiant crossover bundle 240 fluidly connects the convection coil assembly 238 to the radiant coil assembly 202 of the coil assembly 200. The radiant coil assembly 202 has a radiant coil bundle 304 with a radiant coil bundle inlet 306 and a radiant coil bundle outlet 308. When the fired heater 100 contains more than one fluid pass (circuit), the radiant coil bundle outlet 308 can include an outlet manifold 324 to collect to process fluid from the individual flow passes of the radiant coil bundle 304 and combine the total fluid flow to a single fluid pass (circuit). The radiant coil bundle 304 is arranged optimally around the burner 102 for radiant heat transfer to the process fluid from the combustion process.

The radiant coil assembly 202 is supported within the radiant section 106 of the heater 100 by a manifold support assembly 326. The manifold support assembly 326 has a manifold support coil bundle 333 with a manifold support inlet 328 and a manifold support outlet 330. The manifold support coil bundle 333 mechanically supports the radiant coil bundle 304 and also aids in radiant heat transfer to the process fluid.

Turning now to FIGS. 4 through 9, the coil assembly 200 is configured such that the process fluid is discharged from the radiant coil bundle outlet 308 of the radiant coil assembly 202 to the manifold support inlet 328 of the manifold support assembly 326. The manifold support outlet 330 of the manifold support assembly 326 is the process fluid outlet for the fired heater 100.

As exemplified, the process fluid enters the heater 100 at the inlet manifold 348 of the convection coil assembly 238. The process fluid flows through the convection coil bundle 342 to the convection-radiant crossover bundle 240, thereby defining convection flow path 410→412→414→416. The radiant coil assembly 202 receives the process fluid from the convection section 108 of the heater 100 via the convection-radiant crossover bundle 240, and through radiant coil process inlets 306a, 306b, 306c of the radiant coil bundle 304. The process fluid flows through the radiant coil bundle 304, and when the process fluid reaches a distal end of the coil bundle 304, it exits the radiant coil bundle 304 through radiant coil process outlets 308a, 308b, 308c. The radiant coil bundle 304 intermediate of the radiant coil process inlets 306a, 306b, 306c and the radiant coil process outlets 308a, 308b, 308c thereby defines radiant flow path 418a→418b→418c for the process fluid. Although the radiant coil bundle 304 is exemplified with three radiant coil tubes, it will be appreciated that the radiant coil bundle 304 may have more or less coil tubes to facilitate the hydraulic and heat transfer specifics of the particular application.

The process fluid exits the radiant flow path 418a→418b→418c from the radiant coil process outlets 308a, 308b, 308c into the outlet manifold 324 to collect the process fluid, which then flows into the manifold support assembly 326 via a radiant-manifold support crossover 336. The radiant coil bundle 304 is supported by the manifold support assembly 326, which receives the process fluid through the manifold support inlet 328 and releases the process fluid through the manifold support outlet 330, thereby defining a manifold support flow path 418→420→422→424.

Between the manifold support inlet 328 and the manifold support outlet 330, the manifold support bundle 333 includes a plurality of connected manifold pipes 334. The manifold pipes 334 may include a first horizontal pipe 334a and a second horizontal pipe 334b, which are positioned parallel to one another beneath the radiant coil bundle 304 to support the radiant coil bundle 304 lengthwise in a horizontal configuration. In such embodiments, the first and second horizontal pipes 334a, 334b are set apart at a predetermined distance (D) that is smaller than a diameter (d) of the radiant coil bundle 304 to allow the radiant coil bundle 304 to seat atop the first and second horizontal pipes 334a, 334b. The predetermined distance (D) and the selected diameter of the support manifold pipes 334 also maintains adequate spacing between the radiant coil bundle 304 and the refractory lining 120 of the fired process heater 100. To obtain the predetermined distance (D), the horizontal pipes 334a, 334b may be supported by a plurality of guides (not shown) that are welded to the heater casing 112 at locations coincident with external support to carry the load of the radiant coil assembly 202 to grade.

The manifold support assembly 326 is partially exposed to the radiant heat of the firebox and, therefore, transfers marginal heat to the process fluid. The manifold pipe material is also cooled due to heat transfer to the process fluid through the manifold pipes 334 because the process fluid carries away the heat that is passed through heat transfer from the manifold support assembly 326. In some embodiment, the temperature of the process fluid is between about 400° F. and about 600° F. within the manifold pipes 334. By cooling the manifold support assembly 326, the process fluid protects the mechanical integrity of the manifold support assembly 326 and permits the use of manifold pipe materials that would not otherwise provide sustainable support for the radiant coil bundle 304 under the internal flue gas temperatures present in the fired process heater 100. In summary, this cooling feature maintains the temperature of the support, absorbs heat within the heater process, and protects the radiant coil bundle 304.

It will be appreciated that various features of the support manifold assembly 326 may be tailored to the specifications of the fired process heater 100. The manifold support assembly 326 must be designed to withstand the internal project-specific design pressure of the tubular coil assembly 200, plus the external loading from the radiant coil bundle 304. The maximum resultant combined stress in the manifold wall must be less than the published allowable stresses for the material at the design temperature of the manifold pipes 334 (i.e., the maximum calculated metal temperature of the manifold support assembly 326 in view of the pipe material, plus allowance), which may be calculated using commercially available heater rating software. In various embodiments, the manifold pipes 334 may be constructed from metal alloy materials, such as carbon steel or nickel-chrome alloy, and the thickness of the manifold pipes 334 may be selected by analyzing the stresses from the internal pressure and the external loading from the radiant coil bundle 304.

As shown in the exemplary embodiment of FIGS. 4 through 8, the process fluid flows along the radiant flow path 418a→418b→418c (through the radiant coil bundle 304) before flowing along the manifold support flow path 418→420→422→424 (through the manifold support assembly 326). In other words, the process 500 of transferring heat energy to the process fluid involves (i) a step 502 of flowing the process fluid through the convection coil bundle 342 in the convection section 108 of the fired process heater 100, then (ii) a step 504 of flowing the process fluid through the radiant coil bundle 304 in the radiant section 106, and then (iii) a step 506 of flowing the process fluid through the manifold support assembly 326. As shown in FIG. 9, at step 508, the process fluid exits the heater process and is removed from the fired process heater 100.

For some applications, the temperature of the process fluid as it exits the radiant process outlet(s) 308 is too high to maintain the mechanical integrity of the manifold support assembly 326. The temperature of the process fluid as it enters the heater process, however, is generally low enough to cool the manifold support assembly 326 sufficiently. As exemplified in FIGS. 10 through 14, the coil assembly 200 is configured such that the manifold support inlet 328 of the manifold support assembly 326 is the process fluid inlet for the fired heater 100. The manifold support outlet 330 of the manifold support assembly 326 discharges the process fluid to the convection coil bundle inlet 344 of the convection coil assembly 238.

Accordingly, in the exemplary embodiment depicted in FIGS. 10 through 14, the process fluid flows from the inlet 328 along the manifold flow path 430→432 (through the manifold support assembly 326) before flowing to a manifold support assembly-convection crossover bundle 338, to the convection coil bundle 342, to the convection-radiant crossover bundle 240 along flow path 434→438 and to the radiant coil bundle 304, along radiant flow path 440 (through the radiant coil assembly 202). More particularly, heat energy may be transferred to the process fluid according to process 600 at FIG. 15: (i) the process fluid flows through the manifold support assembly 326 at step 602, then (ii) through a convection coil bundle 342 at step 604, and then (iii) through the radiant coil bundle 304 at step 606. At step 608, the process fluid exits the heater process and is removed from the fired process heater 100.

As shown in FIGS. 10 through 14, the radiant coil assembly 202 includes the convection coil bundle 342 positioned intermediate of and in the flow path of the manifold support assembly 326 and the radiant coil bundle 304. After the process fluid enters the radiant section 106 through the manifold process inlet 328, the process fluid flows through the manifold support assembly 326 and exits the coil support manifold outlet 330. The convection tube bundle 342 receives the process fluid via the manifold support assembly-convection crossover bundle 338, flows the process fluid through convection coil bundle 342 (arranged as, e.g., a stacked, serpentine coil), and routes the process fluid to the radiant coil bundle 304 through the convection-radiant crossover bundle 240 to the radiant inlet 306. The convection coil bundle 342 between the support manifold assembly-convection crossover bundle (inlet manifold is not shown in this depiction due to single process pass) 338 and the radiant coil bundle inlet 306 define flow path 434→436→438. The process fluid then flows through the radiant coil bundle 304 and exits the heater process through the radiant process outlet 308.

As used herein, the term “fluidly connected” means connected by a fluid transfer conduit or any other method that permits fluid transfer, with or without intervening elements, such as, without limitation, containers, filters, devices, pumps, valves, etc. A non-limiting example, two tanks or vessels may be “fluidly connected” if they are connected to each other through a pipe or tube, even if a pump, manifold, valve, or other device is placed in-line between the vessels. Two elements are considered to be “fluidly connected” even though there is no pipe or tubing making the connection if the first element leaks or otherwise drains, overflows, siphons, or transfers into the second element, though there may be no actual physical connection between the two elements in the form of a pipe or tube. As used herein, the term “in fluid communication with” means that a fluid-carrying or fluid-transporting member (e.g., vessel, tank, pump, pipe, tubing, disc, valve, channel, port, etc.) is coupled to another fluid-carrying or fluid-transporting member so as to permit the fluid to flow, leak, or otherwise migrate from one member to the other. In reference to a process or circuit, the term “downstream” means a later in the direction of general process and/or fluid flow, and “upstream” means earlier in the direction of general process and/or flow.

The description of the invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “front,” “rear,” “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly” etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the machine be constructed or the method to be operated in a particular orientation. Terms such as “connected,” “connecting,” “attached,” “attaching,” “join,” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece.

For purposes of the disclosure, the term “at least” followed by a number is used herein to denote the start of a range beginning with that number (which may be a ranger having an upper limit or no upper limit, depending on the variable being defined). For example, “at least 1” means 1 or more than 1. The term “at most” followed by a number is used herein to denote the end of a range ending with that number (which may be a range having 1 or 0 as its lower limit, or a range having no lower limit, depending upon the variable being defined). For example, “at most 4” means 4 or less than 4, and “at most 40%” means 40% or less than 40%. Terms of approximation (e.g., “about”, “substantially”, “approximately”, etc.) should be interpreted according to their ordinary and customary meanings as used in the associated art unless indicated otherwise. Absent a specific definition and absent ordinary and customary usage in the associated art, such terms should be interpreted to be ±10% of the base value.

When, in this document, a range is given as “(a first number) to (a second number)” or “(a first number)-(a second number)”, this means a range whose lower limit is the first number and whose upper limit is the second number. For example, 25 to 100 should be interpreted to mean a range whose lower limit is 25 and whose upper limit is 100. Additionally, it should be noted that where a range is given, every possible subrange or interval within that range is also specifically intended unless the context indicates to the contrary. For example, if the specification indicates a range of 25 to 100 such range is also intended to include subranges such as 26-100, 27-100, etc., 25-99, 25-98, etc., as well as any other possible combination of lower and upper values within the stated range, e.g., 33-47, 60-97, 41-45, 28-96, etc. Note that integer range values have been used in this paragraph for purposes of illustration only and decimal and fractional values (e.g., 46.7-91.3) should also be understood to be intended as possible subrange endpoints unless specifically excluded.

Although an overview of the disclosed subject matter has been described with reference to specific example embodiments, various modifications and changes may be made to these embodiments without departing from the broader scope of embodiments of the present invention. For example, various embodiments or features thereof may be mixed and matched or made optional by a person of ordinary skill in the art. Such embodiments of the present subject matter may be referred to herein, individually or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or present concept if more than one is, in fact, disclosed.

The embodiments illustrated herein are believed to be described in sufficient detail to enable those skilled in the art to practice the teachings disclosed. Other embodiments may be used and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. The Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.