Patent Publication Number: US-2021183349-A1

Title: Refractory core with enhanced acoustic properties

Description:
CROSS-REFERENCE TO OTHER APPLICATIONS 
     The disclosure claims priority from U.S. Provisional Application No. 62/947,886 filed Dec. 13, 2019 and 62/976,431 filed Feb. 14, 2020, both of which are hereby incorporated by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The disclosure is generally directed at incinerators and at gas turbines for industrial and energy utility applications and, more specifically, at insulation and noise dampening using a refractory core with enhanced acoustic properties. 
     BACKGROUND 
     The use of incinerators and gas turbines in industrial applications will be well understood. These devices are typically quite noisy when in use and therefore, there is a need to reduce the noise pollution that is generated by these devices. Typical practice for incinerator silencers is to complete the combustion in a conventional stack, mix in fresh tempering air to lower the gas temperature and silence the new combined gas flow. With many current systems, this would require a complete redesign of either the incinerator or its foundations, neither of which is desirable. 
     Therefore, there is provided a novel refractory core with enhanced acoustic properties for use in insulation and noise dampening in industrial applications. 
     SUMMARY 
     The disclosure is directed at a refractory core including insulators and noise dampening for use in an exhaust stack. To alleviate some of the problems that may arise using conventional acoustic silencers (i.e. noise dampeners), the disclosure is directed at a system that includes, in one embodiment, a free-standing insulation core made using a framework and stacked insulators which is then inserted into an exhaust stack. 
     In an embodiment, the disclosure may be seen as a pre-assembled refractory core for use in an acoustic silencer incorporated into an incinerator stack. The refractory core provides silencing inside the walls of the incinerator, retaining inasmuch as possible, the aerodynamic and dispersion characteristics of the incinerator without the integration of the refractory core. In one aspect of the disclosure, there is provided a refractory core with enhanced acoustic properties including a framework; a set of spears having a set of platforms, the set of spears integrated with the framework; and a set of insulation segments resting atop the set of platforms. 
     In another embodiment, the framework includes at least one circular ring. In a further embodiment, the at least one circular ring includes a plurality of arced segments. The set of spears may be different lengths and different designs. In one embodiment, an end of a spear is inserted through a hole in the framework and then turned to “lock” the spear in place. The set of insulation segments may include noise dampening slots. 
     In one aspect of the disclosure, there is provided a refractory core with enhanced acoustic properties including a framework including a set of circular rings having a plurality of apertures; a set of spears, the set of spears extending through the plurality of apertures; a set of platforms, each of the set of platforms individually integrated with one of the set of spears; and a set of insulation segments, the insulation segments held in place by the set of platforms. 
     In another aspect, each of the set of circular rings include a plurality of arced segments that form a circle when placed adjacent each other. In a further aspect, the arced segments are fastened in place by welding, screwing, bolting or pinning. In yet a further aspect, the arced segments are locked in place by at least one of the set of spears. In an aspect, a plurality of the set of platforms are integrated with each spear of the set of spears, the plurality of platforms spaced a predetermined distance apart along each spear. 
     In yet another aspect, the set of spears form a circle when inserted through the plurality of apertures. In an aspect, platforms integrated with one of the set of spears are staggered with respect to platforms integrated with an adjacent one of the set of spears. In a further aspect, the disclosure includes a casing for housing the refractory core. In another further aspect, the framework is integrated with the casing. In yet another aspect, the insulation segments include noise dampening slots. In a further aspect, the set of spears includes spears having at least two different lengths. 
     In a further aspect, the set of insulation segments includes layers of insulation segments placed atop each other. In another aspect, the layers of insulations segments are staggered with respect to each other in adjacent layers. 
     In another aspect of the disclosure, there is provided a refractory core with enhanced acoustic properties including at least two refractory core modules, each of the at least two refractory core modules including: a framework including a set of circular rings having a plurality of apertures; a set of spears, the set of spears extending through the plurality of apertures; and a set of insulation segments, the insulation segments including holes for receiving the set of spears; wherein at least some of the set of spears from one of the at least two refractory core modules extends into the set of insulation segments of another of the at least two refractory core modules to hold the at least two refractory core modules together. 
     In a further aspect, an end of each of the set of spears further comprise openings for receiving wire to hold the at least two refractory core modules against each other. In yet a further aspect, the disclosure further includes a casing for housing the at least two refractory core modules. In yet another aspect, the disclosure further includes a set of clips for attaching the at least two refractory core modules to the casing. 
     In another aspect, the disclosure includes a central support for supporting each of the set of spears. In a further aspect, the central support comprises individual tabs for each of the set of spears. In yet another aspect, the central support is integrated with the casing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures. 
         FIG. 1  is a perspective view of a framework for a refractory core; 
         FIG. 2  is a top view of a platform; 
         FIG. 3  is a schematic view of a locking portion of a vertical spear; 
         FIG. 4  is a perspective view of a vertical spear inserted through a circular ring; 
         FIG. 5  is a view of a refractory core; 
         FIG. 6 a    is a top view of an insulation segment; 
         FIG. 6 b    is a top view of another embodiment of an insulation segment; 
         FIG. 7 a    is a schematic view of a refractory core clip installed in a casing; 
         FIG. 7 b    is a perspective view of the refractory core clip; 
         FIG. 8  is a perspective view of another embodiment of a refractory core module; 
         FIG. 9  is a side view of a pair of refractory core modules; 
         FIG. 10  is a perspective view of a pair of refractory core modules; 
         FIG. 11  is a side view of a refractory core; 
         FIG. 12  is a perspective view of a refractory core; 
         FIG. 13 a    is a top view of an insulation layer; 
         FIG. 13 b    is perspective view of an insulation layer; 
         FIG. 14 a    illustrates a spear with one type of notch; 
         FIG. 14 b    illustrates a spear with another type of notch; 
         FIG. 15 a    illustrates a front view of another embodiment of a refractory core; 
         FIG. 15 b    is a cross-section taken along line  15   b - 15   b  of  FIG. 15   a;    
         FIG. 16  is a perspective view of another embodiment of a framework for a refractory core; 
         FIG. 17  is a perspective view of yet another embodiment of a framework for a refractory core; 
         FIG. 18  is a perspective view of a further embodiment of a framework for a refractory core; and 
         FIG. 19  is a top view of an embodiment of a refractory core. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure is generally directed at a refractory core that is integrated, incorporated or otherwise used within an exhaust stack. In one embodiment, the refractory core may be seen as a combined insulator and acoustic noise dampener. In another embodiment, the refractory core includes at least one framework that includes a set of vertical spears that form a generally circular/cylindrical pattern for housing or receiving segments of insulation, or blanket segments. 
     Turning to  FIG. 1 , a perspective view of a portion of an embodiment of a refractory core, or framework  10 , is shown. In some embodiments, the refractory core may be modular and include more than one refractory core module as will be discussed in more detail below. 
     The framework  10  includes at least one circular ring  12  that receives a set or plurality of vertical spears  14  (via a set of openings), whereby each of the vertical spears  14  includes a set of platforms  16  located at predetermined distances from each other along the vertical spear  14 . In other words, the vertical spears  14  may be integrated with the circular ring  12  and the platforms  16  are supported by and/or connected to the vertical spears  14 . In some embodiments, each of the set of vertical spears is a same length. Alternatively, within the set of vertical spears, there may be at least two different lengths of spears. An embodiment with two different lengths of spears, seen as a long spear  14   a  and a short spear  14   b  is discussed in more detail below. In some embodiments, the at least one circular ring  12  of the framework  10  may include a set of arced segments assembled into a ring, a set of arced segments attached to a casing, a ring attached to a casing, or a set of tabbed portions attached to a casing, as discussed in more detail below. 
     In some embodiments, each of the set of platforms  16  is a washer that is located a predetermined distance (e.g. approximately 12″) away from an adjacent washer (or platform) on the same vertical spear  14 . In other embodiments, the distance between platforms may be varied based on the design and requirements of the refractory core. In the embodiment of  FIG. 1 , the set of platforms  16  on one spear are staggered with respect to platforms  16  on other vertical spears, however, they may also be aligned with each other depending on a design of the refractory core. Although not shown in  FIG. 1 , insulation or blanket segments rest atop the platforms or may be held in place by the platforms  16 . 
     In the embodiment illustrated in  FIG. 1 , the circular ring  12  includes two stacked rows of annular segments joined by the locking action of the spears. The annular segments may be arced segments. Alternatively, the ring may be a single monolithic piece of material, or of annular segments joined by welding, screwing, bolting, pinning or any other conventional fastening system deemed suitable to the particular application. 
       FIG. 2  provides a top view of an example configuration of one of the platforms. The platform  16  includes a central hole  18  (where the vertical spear  14  passes through) and whereby the platform  16  may rotate with respect to the spear  14  to “lock” the platform in to place. The platform  16  may further include a pair of adjacent holes, or openings,  20  for receiving a tool to assist the process of rotation (such as with respect to the platform and the spear), as needed, depending on the as-fabricated clearance or interference between the central hole  18  and the spear  14 . 
     In some embodiments, the refractory core may be modular, having a plurality of refractory core modules integrated with each other to form the refractory core. The number of refractory core modules may be determined based on criteria such as, but not limited to, height required. In embodiments of the disclosure, the refractory core and the refractory core modules are designed to address thermal expansion problems that are experienced by some current systems. In one embodiment, two refractory core modules are used in order to reduce the likelihood that thermal expansion will become an issue, as it might in a concentrated area using a single elongated refractory core module. While in some embodiments, the sizes of each of the refractory core modules are identical, the sizes of each refractory core module may also be different from each other. 
     In general, thermal expansion may be intrinsic or extrinsic. With intrinsic expansion, thermal expansion may be experienced by the steel framing (or framework) of the refractory core while, with extrinsic thermal expansion, the expansion is experienced in the components upstream or downstream from the refractory core that it connects to thermally and as a fluid conduit. Embodiments of the disclosure address these thermal expansion issues. In some embodiments, intrinsic thermal expansion may be addressed by the embodiment(s) shown in  FIGS. 1 to 6   a  and  7  and extrinsic thermal expansion may be addressed by the embodiment(s) shown in  FIGS. 6 b    and  8  through  12 . 
     In some embodiments, there is a casing to house the refractory core whether it is a single framework, a pair of refractory core modules or more than a pair of refractory core modules. The casing provides lateral support and location for the refractory core or refractory core modules and may, in some cases, be a structural part of the exhaust stack. 
     In one embodiment, wherein the refractory core includes two refractory core modules, the long spears  14   a  of one of the refractory core modules are aligned with the short spears  14   b  in the other of the refractory core modules. Alignment of the long spears in one of the refractory core modules and the short spears  14   b  in the other of the refractory core modules assists to accommodate thermal expansion of the spears  14  of framework  10 . In some embodiments, the length of the spears are designed to have free space between the tips to accommodate expansion in length to a high or maximum theoretical length. 
     Furthermore, in order to enable compression of some insulation segments due to the expansion of the spears, a buffer section of insulation material may be installed between the two refractory core modules, such as at a top of the lower refractory core module. This buffer section is preferably not pre-compressed by any platforms, but is left free to compress or expand according to the varying pressure applied to it. When the two refractory core modules are integrated, this buffer section preferably becomes compressed to a low or minimum level. In one embodiment, the buffer section is compressed to around 33%. 
     Compression due to expansion of the spears may be accommodated by additional compression of this buffer section or middle layer. It will be understood that this buffer section may be thicker than the distance between staggered platforms  16 . As a consequence of this buffer layer or section, the spears may be different between the upper and lower refractory core modules and a deviation from the typical platform spacing may be required. 
     In some initial testing, the stiffness of the compressed buffer layer was sufficient to overcome the self-weight of the top refractory core module. Additional compressive force may be required to install the refractory core in the casing to its correct height depending on the ratio of module weight to cross-sectional area. In the current embodiment, the balance between compression and force due to weight is approximately close to neutral, requiring little additional downward force to complete the insertion of the core into the casing. 
       FIG. 3  shows a view of a locking portion of the vertical spear at a point where the circular ring is connected.  FIG. 4  shows the same portion of the spear when inserted through the circular ring. 
     As can be seen in  FIG. 3 , the locking portion  22  of the vertical spear  14  includes an opening, or hole,  24  and a set of notches  30 . In the current embodiment, the locking portion  22  includes a pair of notches  30 . The opening  24  may be used to fasten extra ring segments installed on the outside face of the rings  12  particularly as illustrated above and below the stack as shown in  FIGS. 11 and 12  by passing a wire down through the insulation segment through the hole  24  and back up. 
     In  FIG. 4 , a schematic diagram of the spear twisted in the axial direction is shown. In order to lock the spear  14  within the circular ring, after the spear  14  has been inserted through an opening  26  in the circular ring  12 , the spear  14  can be twisted or rotated (about 90 degrees) in an axial direction so that it is placed in a twisted position. Twisting or rotation of the spear is, for example, in the direction of arrow  28 . The pair of notches  30  reduce or prevent the likelihood of the spear  14  passing back through the opening  26  after it has been twisted and locked in place. In this embodiment, this locking mechanism avoids the need for welding of the spear  14  to the circular ring  12  which may introduce potential material failure points. 
     As will be understood, a width, W s , of the spear  14  is somewhat equal to a length, L o , of the opening  26  and greater than a width, W o , of the opening  26 . 
     An advantage of the locking system or locking mechanism, is that it includes protective measures to reduce the likelihood that the spear  14  would slip out of the opening  26  after it has been inserted. One protective mechanism, is that the about 90 degree turn of the spear (enabled by the notches  30 ) results in the width (W s ) of the spear being larger than the width (W o ) of the opening. A second protective measure is that the insulation segments are slotted or positioned to prevent or reduce the likelihood of rotation of the spear once they have been installed. 
     Turning to  FIG. 5 , a schematic diagram of an embodiment of a refractory core module is shown. As can be seen in  FIG. 5 , the refractory core module includes the set of spears  14  with each of the spears  14  including a set of platforms  16  spaced a predetermined distance apart along the spear. Resting atop the platforms  16  are a set of blanket insulation segments  42 . Each layer  44  of insulation segments  42  includes a plurality of insulation segments placed side by side. Multiple insulation segments are placed adjacent to each other such that an inner portion of the insulation segments forms a circle or arc with the adjacent segments. In some embodiments, the position of the insulation segments  42  in a layer  44  are staggered with respect to a position of the insulation segments in an adjacent layer. In other words, the insulation segments may not be aligned with each other from layer to layer.  FIGS. 13 a  and 13 b    are top and perspective views of an insulation layer. 
     In some embodiments, the refractory core includes more than one refractory core module with insulation segments that are stacked atop each other. 
     As discussed above, in some embodiments, for each refractory core or refractory core module, the set of vertical spears includes long and short spears. In some embodiments, the shorter spear  14   b  extends from the circular ring a distance that is slightly past its highest platform while the longer spear  14   a  provides adequate locational support and assists in maintaining uniform compression of the insulation segments of the buffer section. 
     Individual insulation segments (such as the one schematically shown in  FIG. 6 a   ) are placed atop different platforms that receive and support the segments. 
     As can be seen in  FIG. 6 a   , the insulation segment  42  includes a somewhat circular inner profile  50  that, when placed adjacent other insulation segments in the same layer  44 , define a circular shape. 
     The insulation segment  42  may further include a set of noise dampening slots, or cut-outs,  54  that provide improved silencing and noise dampening compared with current systems. The cut-outs increase the surface area exposed to acoustic energy and thus lead to noise attenuation. The set of noise dampening slots  54  are preferably staggered around a circumference or the inner profile  50  of the insulation segment  42 . In one embodiment, the spacing of the slots  54  may be determined based on the wavelength of sound or noise that is being dampened. The spacing may also be determined based on requirements for reducing a turbulence of flow within the exhaust stack. 
     With current systems, use of at least some types of rigidizing treatment for the insulation tends to close the pores between the fibers in the insulation segments, which degrades or reduces acoustic silencing or noise dampening performance. While the current embodiment uses a rigidizing treatment due to the speed of the gas in the stack, an advantage of the current embodiment is that the interior faces of the noise dampening cutouts  54  will typically not receive significant amounts of rigidizer, thus leaving the pore size of the insulation segment as large as possible, thereby increasing or maximizing the acoustic energy admitted into the insulation. This results in improved noise attenuation. 
       FIG. 6 b    provides a schematic diagram of another embodiment of an insulation segment, which may also be seen as an expansion insulation segment. In this embodiment, the expansion insulation segment  70  is placed in an area where the flow is faster and the expansion insulation segment  70  may experience increased compression per cycle than in areas where the flow is not as fast (such as may be experienced by the insulation segment of  FIG. 6 a   ). The expansion insulation segment  70  may be more resistant to erosion. 
     Turning to  FIG. 7 a   , a schematic diagram of a refractory core clip installed in a casing is shown. A perspective view of the clip is shown in  FIG. 7 b   . In a refractory core having more than one refractory core module, over time, one of the refractory core modules (typically the top refractory core module) may settle downward, potentially opening a gap in the insulation near an associated flange. In order to prevent or reduce the likelihood of this happening, the refractory core module may include a set of clips that is attached to the casing holding the two refractory core modules to support at least a portion of the framework of the refractory core module. 
     As can be seen in  FIG. 7 a   , the clip  60  is installed with one end under a circular ring  12  of the refractory core module straddling a spear with the forked end. The clip is attached at the other end to the casing  62 . In a present embodiment, to enable a closer fit between the casing and the refractory core module, the refractory core module may be wrapped with more or increased insulation which is compressed before insertion into the casing and then released to expand. In another embodiment, a thickness of the insulation segment may be changed such that there is little or no compression required before the refractory module is inserted into or attached to the casing. 
     Turning to  FIGS. 8 to 12 , various perspective and side views of another embodiment of a refractory core are shown.  FIG. 8  is a perspective view of a refractory core module  100 . The refractory core module  100  includes a circle, or circular, ring  101  that includes a plurality of circle ring segments  102  that form a circle when integrated with each other. In other words, the ring  101  is composed of overlapped circle ring segments  102  that are locked together via a vertical spear  106  (such as disclosed above). In the current embodiment, the circle ring segments  102  are arced segments. The circle ring segments  102  include openings  104  that receive the vertical spears  106 . 
     In the present embodiment, portions of the circle ring segments overlap each other such that a locking end of a vertical spear (such as a longer spear  106   a ) is placed through the openings  104  of two overlapping segments  102 . As described above, an approximate 90 degree axial rotation or twisting of the longer spear  106   a  after it has been passed through the openings  104  enables the longer spear  106   a  to be locked in place along with the two adjacent circle ring segments  102 . In some cases, shorter vertical spears  106   b  may pass through a single opening  104  (when the opening is in a middle of the circle ring segment  102 ) and then locked in place. Alternatively, the positioning of the longer  106   a  and shorter  106   b  vertical spears may be switched whereby the shorter vertical spears  106   b  lock the two adjacent arced segments  102 . In another embodiment, the vertical spears may all be the same length such that the vertical spears that are used to lock the two adjacent arced segments  102  are the same length as the vertical spears located in the single opening. 
     Schematic diagrams of different types of spears are shown in  FIGS. 14 a  and 14 b   . In the spear of  FIG. 14 a   , the notch  30  is sized to receive or catch a pair of circle ring segments while the spear of  FIG. 14 b    has a notch  30  sized to receive or catch a single ring segment. 
     After the spears  106  are locked in place and the circular ring “completed”, segments of insulation  108  can then be placed into the refractory core module  100 . In some embodiments, the segments of insulation in each layer are aligned with segments of insulation in adjacent layers. Typically, the insulation segments are pushed onto the spears.  FIG. 9  is a side view of a pair of refractory core modules  100  prior to being connected or integrated together. 
     As can be seen in  FIG. 10 , in some embodiments, each insulation segment  108  is inserted onto or “stabbed” by a spear  106  to assist in keeping the insulation segment in place with respect to the refractory core module  100 . In the current embodiment, there are no platforms connected to the spears. In some embodiments, the refractory core modules include insulation segments having twice as many slots for spears as the number of spears in the module. This allows the spears from the other refractory core module to be inserted into the empty slots such as for alignment and for expansion. As can be schematically seen in  FIG. 10 , the insulation segments  108  in the bottom refractory core module  100  includes openings  130  for receiving spears  106  from the top refractory module. 
       FIG. 11  is a side view of a pair of connected refractory core modules. In the current embodiment, the two refractory core modules are held together via wire holds  110  after the insulation segments or layers have been compressed. As discussed above, the wire holds may pass through holes or openings  24  in the spears  106 . After the refractory core is put together, further insulation segments  132  or layers of insulation may be placed at a top or a bottom of the refractory core to cover the ends  134  of the spears that may be still showing. The further insulation segments may be held in place by the portion of the spears  134  that are still visible. Turning to  FIG. 12 , a perspective view of  FIG. 11  is provided. 
     In an alternative embodiment, shorter casings may be contemplated to reduce the need for separate floating refractory core modules. 
     Turning to  FIG. 15 a   , a front view of another embodiment of a refractory silencer core is shown. In the current embodiment, the refractory core  1000  includes a casing  1002 . Turning to  FIG. 15 b   , which is a cross-sectional view taken along line  15   b - 15   b  of  FIG. 15 a   , the refractory core  1000  includes a plurality of layers  1004  of insulation segments  1006 . In the current embodiment, adjacent layers  1004   a  and  1004   b  are staggered with respect to each other. 
     Turning to  FIG. 19 , a top view of the refractory core of  FIG. 15  is shown.  FIG. 19  provides a schematic view of how the insulation segments may be staggered with respect to each other within the refractory core. In  FIG. 19 , the insulation segments  1006  in the first, top or closest layer  1004   a  of insulation segments  1006  are shown in solid lines while the insulation segments  1006  of the adjacent layer  1004 b are shown in dotted lines. In the current embodiment, the insulation segments in layer  1004   b  are flipped with respect to the insulation segments  1006  in layer  1004   a  to provide the staggered positioning of the notches  1007  between layers. The insulation segments are held in place by spears  1008  such as described above. 
     Turning to  FIG. 16  a perspective view of a half portion of an embodiment of a framework for the refractory core is shown. The framework  1010  is connected to, mounted to, or integrated with, the casing  1002 . Typically, the complete framework  1010  is circular in shape. 
     In the current embodiment, the framework  1010  of  FIG. 16  includes a set of circular end rings  1012 . In other embodiments, the end rings may be separate from the framework  1010 . Typically, the end rings  1012  act as retainers to reduce the likelihood or to prevent the insulation segments from falling out of the framework, or casing, during shipping and handling, however, depending on the refractory core set-up, the set of end rings  1012  may also be for receiving and holding a set of spears  1008  in place. The set of circular end rings  1012  may be a single piece ring or may be made up of arced segments that form a circle when placed side by side. 
     The circular end rings  1012  include a set of holes for receiving the spears  1008 . In one embodiment, the spears  1008  may not initially extend through the holes but may do so due to thermal expansion of the spears  1008 . In another embodiment, some of the spears  1008  may initially extend through at least one hole in an end ring and be locked in place. One method of locking a spear in place is discussed above. 
     The framework  1010  further includes a support, or central support, ring  1013  located between the two end rings  1012  for supporting the set of spears  1008 . In the current embodiment, the support ring  1013  is spatially located in the middle between the two end rings although the position of the support ring  1013  may be in any location between the end rings  1012 . In the current embodiment, the support ring  1013  is made up of arced segments  1015  that form a circle when placed side by side. 
     The spears  1008  are preferably pointed at each end to pierce through the insulation segments when they are layered within the framework  1010  (such as shown in FIG.  15   b ). As with some embodiments above, support platforms  1016  are located at predetermined positions along the spears  1008  to provide further support to, or to hold the insulation segments when they are placed within the framework or refractory core. In one embodiment, the spears  1008  are locked to the support ring  1013  similar to the manner discussed above. The platforms  1016  may or may not be mounted or integrated with the casing. 
     Turning to  FIG. 17 , a perspective view of a portion of another embodiment of a framework for the refractory core is shown. As with the embodiment of  FIG. 16 , the framework  1020  is connected to, or integrated with, the casing  1002 . In some embodiments, the framework  1020  may be manufactured separated from the casing and may simply be placed within an existing casing. 
     The framework  1020  of  FIG. 17  includes a set of circular end rings  1022  located at opposite ends of the framework  1020 . As discussed above, the end rings  1022  may or may not be part of the framework  1020  depending on the design or requirements of the refractory core. The circular end rings  1022  include holes for receiving ends of spears  1024  such as disclosed above. The framework  1020  further includes central, or tabbed, support portions  1026  that are mounted, or attached, to the casing  1002  such that the tabbed portions  1026  may be seen as being integrated with the casing  1002 . Each of the central portions  1026  include an opening, or hole,  1028  for receiving a spear  1024 . One of the functionalities of the central portions  1026  is to house a portion of the spears to guide and/or support the spears  1024 . As can be seen, in the current embodiment, the spears  1024  are identical with points at both ends and have a length along a long axis of the spears  1024  that is shorter than a height of the refractory core. The height of the refractory core may be seen as the length of the refractory core parallel to the long axis of the spears  1024 . Although not shown, it is understood that the central portions  1026  continue around the inside of the entire circular casing or framework. The framework may also include platforms  1025  which may or may not be mounted or integrated with the casing  1020 . 
     Turning to  FIG. 18 , a perspective view of a portion of another embodiment of a framework for the refractory core is shown. The embodiment of  FIG. 18  is similar to the embodiment of  FIG. 16  with the difference being the support ring  1030 . In the current embodiment, the support ring  1030  is a single circular piece. In one embodiment, the support ring  1030  is mounted to the inside of the casing such that it stays in place when the refractory core is installed within an incinerator. The support ring  1030  performs the same functionality as the support ring  1013  of  FIG. 16 . 
     As with the embodiment of  FIG. 16 , the framework includes end circular rings  1012  that receive the ends of spears  1008  due to thermal expansion and/or to lock the spears in place. 
     Although the present disclosure has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present disclosure. 
     In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details may not be required. In other instances, well-known structures may be shown in block diagram form in order not to obscure the understanding. For example, specific details are not provided as to whether elements of the embodiments described herein are implemented as a software routine, hardware circuit, firmware, or a combination thereof.