Patent Application
20200103171
This application claims the benefit under 35 USC § 119(a)-(d) of U.S. Provisional Application No. 62/485,526 filed on Apr. 14, 2017, the entire contents of which are incorporated herein by reference.
The present invention relates to a retention mechanism for refractory inserts for refractory blocks and refractory block assemblies including those refractory insert, for use in connection with a refractory tunnel, also known as a reformer flue gas tunnel, of a hydrogen reformer furnace, which is used in steam methane reformer processes. More specifically, the present invention provides an improved retention mechanism for refractory inserts that are installed in refractory blocks to control process parameters, such as to provide improved gas flow control. The refractory inserts and refractory block assemblies including those refractory inserts can be used in connection with any conventional refractory block in any refractory tunnel or array, but are preferably used in connection with a light-weight, free-standing tunnel structure that is constructed without the use of mortar, that better withstands the application of hydrogen reformers, and which includes refractory components having a more mechanically robust design and made of higher performance material than that which has been used heretofore.
Refractory orifice inserts (otherwise known as refractory inserts) are used in primary reformer flue gas tunnel system to establish the final hole diameters through which flue gas is channeled from the furnace chamber or radiation zone to the heat recovery section or convective zone of the reformer. A full description of such refractory inserts is provided in PCT/US16/61307, which is incorporated herein by reference.
Prior art refractory orifice inserts are round with a diameter ranging from 3 to 6 inches and fit into a corresponding hole in the sidewall refractory block. The periphery of the refractory insert has a continuous circumferential slot that, at assembly, engages tabs in the inner sidewall of the block hole. Segments of the walls of this circumferential slot are omitted to allow the insert to axially pass by the tabs in the sidewall block hole from either side. Once the tab is near the axial center of the refractory orifice insert circumferential slot, the refractory insert is rotated so that the tabs are captured in the circumferential slot. The insert is then prevented from translating axially in the side block hole by more than the axial clearance between the tabs and the slot. The axial clearance between the walls of the circumferential slot and the tabs to allow for rotation ranges from 0.040″ to 0.070″. Mortar and/or a ceramic fiber gasket are used to prevent the orifice insert from rotating to the point where the tabs could pass through the omitted segments in the circumferential slot walls allowing the insert to dislodge from hole of the block.
It should be noted, however, that the pressure drop from the flue gas flow imparts an axial force on the refractory orifice inserts that can push them out of the block hole. The sole reliance on the mortar and/or ceramic fiber to prevent over rotation, to the point where the refractory orifice insert can axially pass the tabs, however, is problematic. Additionally, some end users object to the use of mortar and/or ceramic fiber for this purpose. In either case, the loss of one or more orifice inserts is significantly detrimental to system performance. Accordingly, there is a need for an additional means to prevent unwanted rotation and axial displacement in connection with refractory inserts that are installed in the holes of refractory blocks.
The refractory inserts according to the present invention can be used in conjunction with any opening/through-hole location in any brick of any tunnel system. This provides a modular system and allows for a universal refractory insert-mating tab to be provided on the surface of the openings (through-holes) of blocks (bricks) that can be used in conjunction with any type of refractory insert member in any location in a tunnel. Such flexibility allows the end user to modify the installation of refractory inserts in any manner that they deem necessary, depending on the particular processing concerns that they may face.
To date, the prior art does not include any universally applicable refractory inserts that can be easily installed in the openings in any block in any location(s) desired by the end user and robustly held in place without the use of mortar to control the flow dynamics in any manner that is required for any particular type of application.
The object of the present invention, therefore, is to provide refractory inserts, having an improved retention mechanism, for use in connection with refractory blocks for any tunnel structure, but preferably in connection with a light-weight, free-standing tunnel structure, constructed without the use of mortar, that better withstands the application of hydrogen reformers, using more mechanically robust refractory components that are made of higher performance material. More specifically, it is an object to the present invention to overcome the drawbacks of the prior art by providing one or more refractory inserts that are installed in openings of refractory blocks to provide refractory block assemblies to control processing conditions, such as the gas flow conditions, in such a tunnel system, and which will not be subject to displacement or loss upon experiencing pressure drops.
According to a first aspect of the present invention, a refractory insert is provided, comprising a main body part having a first surface defining a first sidewall, an opposed second surface defining a second sidewall, an outer peripheral surface separating the first and second surfaces, and a mechanical mating member provided on at least a portion of the outer peripheral surface thereof. The mechanical mating member comprises a retention mechanism for controlling and retaining a position of a corresponding mating member in connection therewith.
The mechanical mating member preferably comprises at least two diametrically opposed channels in the outer peripheral surface of the refractory insert, wherein the channels are circumferentially defined by the first and second sidewalls. The retention mechanism comprises a retention projection member that projects axially inward from one of the first and second sidewalls proximate a first end of each channel and a rotational stop member defining an opposed second end of each channel. Preferably, the retention projection member projects into the channel axially from one of the sidewalls of the insert facing upstream.
It is also preferred that the retention mechanism of the mechanical mating member comprises at least two diametrically opposed slots, formed in the surface of at least one of the first and second sidewalls, and open to the respective channels at least at the first ends thereof proximate the retention projection member. Further, the refractory insert preferably comprises installation notches, formed on portions of at least one of the sidewalls, facing downstream and extending diametrically inward toward the opposed sidewall. Preferably, the refractory insert member is a gas flow changing plug having a central opening that can vary in size, or be closed off entirely (i.e., no central opening).
According to a second aspect of the present invention, a refractory block assembly is provided, comprising a refractory block having at least one opening (through-hole) formed therein, and at least one refractory insert that resides within the at least one opening (through-hole) in the refractory block. The at least one refractory insert preferably comprises a main body part having a first surface defining a first sidewall, an opposed second surface defining a second sidewall, and an outer peripheral surface separating the first and second surfaces, and a mechanical mating member provided on at least a portion of the outer peripheral surface thereof. The mechanical mating member comprises a retention mechanism for controlling and retaining a position of a corresponding mating member provided on an inner surface of the opening in the block.
Preferably, the retention mechanism of the mechanical mating member comprises at least two diametrically opposed channels in the outer peripheral surface of the refractory insert, the channels being circumferentially defined by the first and second sidewalls, and the retention mechanism preferably comprises a retention projection member that projects into the channel axially inward from one of the first and second sidewalls proximate a first end of each channel, and a rotational stop member defining an opposed second end of each channel. It is also preferred that the refractory insert member is a gas flow changing plug having a central opening that can vary in size, or be closed off entirely (i.e., no central opening).
According to another aspect of the present invention, a refractory block assembly for a steam reformer furnace tunnel is provided. The refractory block assembly comprises a refractory block having a hollow main body portion having an outer peripheral surface defining a first end, an opposed second end, an upper surface, an opposed lower surface, a first side and an opposed second side, at least one through-hole having openings formed in the first side and the opposed second side of the main body portion, and a refractory insert that resides within at least one of the at least one though-hole. The refractory insert comprises a main body part having a first surface defining a first sidewall, an opposed second surface defining a second sidewall, and an outer peripheral surface separating the first and second surfaces, and a mechanical mating member provided on at least a portion of the outer peripheral surface thereof. The mechanical mating member comprises a retention mechanism for controlling and retaining a position of a corresponding mating member provided on an inner surface of the at least one through-hole. The refractory block further comprises at least one first mechanical mating portion defining a protruded portion extending from a portion of the upper surface of the main body portion, and at least one second corresponding mechanical mating portion defining an opening corresponding to the protruded portion formed in a portion of the lower surface the main body portion.
Preferably, the retention mechanism of the mechanical mating member of the refractory insert comprises at least two diametrically opposed channels in the outer peripheral surface of the refractory insert, the channels being circumferentially defined by the first and second sidewalls, and the retention mechanism comprises a retention projection member that projects into the channel axially inward from one of the first and second sidewalls proximate a first end of each channel and a rotational stop member defining an opposed second end of each channel.
According to another aspect of the present invention, a refractory tunnel assembly for a steam reformer tunnel is provided, comprising a plurality of refractory base components, a plurality of refractory wall blocks, wherein at least a portion of the plurality of refractory wall blocks further comprise at least one through-hole defining openings formed in opposed side surfaces thereof, a plurality of refractory lid components, and at least one refractory insert residing within at least one of the though-holes in the refractory wall blocks. The refractory insert has a main body part having a first surface defining a first sidewall, an opposed second surface defining a second sidewall, and an outer peripheral surface separating the first and second surfaces, and a mechanical mating member provided on at least a portion of the outer peripheral surface thereof. The mechanical mating member of the refractory insert comprises a retention mechanism for controlling and retaining a position of a corresponding mating member provided on an inner surface of the one or more through-holes of the wall block. The refractory base components are arranged to extend in a horizontal arrangement direction defining a width of the tunnel assembly and a longitudinal arrangement direction defining a length of the tunnel assembly. The refractory wall blocks are stacked upon the base components in a vertical arrangement direction and along the longitudinal arrangement direction, and are stacked upon one another in both the vertical and longitudinal arrangement directions to define two parallel tunnel walls, spaced a distance apart from one another in the horizontal arrangement direction. The tunnel walls extend upwardly from the refractory base components in the vertical arrangement direction and along the length of the tunnel assembly on the refractory base components. The plurality of refractory lid components are stacked upon the wall blocks in the vertical arrangement direction and along the longitudinal arrangement direction, so that the refractory lids extend along the longitudinal arrangement direction and the horizontal arrangement direction in order to cover the distance between the tunnel walls along at least a portion of the length of the tunnel assembly.
Preferably, the plurality of refractory base components comprises hollow refractory base components, and each hollow refractory base component comprises a plurality of corresponding mechanical mating members. Preferably, the plurality of refractory wall blocks comprises a plurality of hollow refractory wall blocks, each hollow refractory wall block comprising a plurality of corresponding mechanical mating members that further correspond to the mechanical mating members of the hollow refractory base components. It is preferred that the plurality of refractory lid components are hollow refractory lid components, wherein each hollow refractory lid component comprises a plurality of mechanical mating members that further correspond to the mechanical mating members of the hollow refractory base components and the hollow refractory wall blocks. Preferably, the hollow refractory wall blocks are stacked upon and mechanically interconnected to the refractory base components via the corresponding mechanical mating members in the vertical arrangement direction and along the longitudinal arrangement direction, and are stacked upon one another and mechanically interconnected to another via the corresponding mechanical mating members, without the use of mortar, in both the vertical and longitudinal arrangement directions, to define the two parallel tunnel walls that are spaced apart from one another in the horizontal arrangement direction. It is also preferred that the plurality of hollow refractory lid components are stacked upon and mechanically interconnected to the hollow refractory wall blocks via the mechanical mating members, without the use of mortar, in the vertical arrangement direction and along the longitudinal arrangement direction, so that the hollow refractory lids extend along the longitudinal arrangement direction and the horizontal arrangement direction. It is also preferred that the refractory base components, the refractory wall blocks, the refractory lid components, and the refractory inserts all comprise the same material.
The retention mechanism of the mechanical mating member of the refractory insert member preferably comprises at least two diametrically opposed channels in the outer peripheral surface of the refractory insert, the channels being circumferentially defined by the first and second sidewalls, and wherein the retention mechanism comprises a retention projection member that projects axially inward from one of the first and second sidewalls proximate a first end of each channel and a rotational stop member defining an opposed second end of each channel. It is preferred that the retention projection member projects axially inward from one of the refractory insert sidewalls of the insert facing upstream. The mechanical mating member of the refractory insert preferably comprises at least two diametrically opposed slots, formed in the surfaces of the first and second sidewalls, and open to the respective channels.
While the refractory insert according to the present invention are preferably used in conjunction with the reduced-weight refractory blocks according to U.S. patent application Ser. No. 15/307,054, the entirety of which is incorporated herein, it should be noted that the refractory inserts according to the present invention can likewise be readily inserted in conjunction with any standard refractory brick (blocks) having the requisite through-hole, and can likewise be used in any standard refractory brick tunnel. In that case, for example, a standard brick or a pre-cast brick sized piece can be modified to include a through-hole having a mechanical mating feature (e.g., a tab) that is either pre-formed on (i.e., machined or cast) or later added onto (adhered) the inner surface thereof to engage the refractory insert member in the same manner described herein.
Proper material selection and installation procedures are also important to prevent “snaking.” Many materials will increase in overall dimension when re-heated, increasing variability and adding challenge to the thermal expansion management. Because the coefficient of thermal expansion for refractory components is nonlinear, it must be fully characterized and understood to ensure that proper expansion joints are created. Selecting a suitable material has always been about compromise and sacrifice in connection with conventional tunnel designs. That is, conventionally, bricks that have sufficient insulating value to keep the furnace supports from deforming do not always also have enough strength to adequately support the tunnel system, and bricks with higher strengths do not have the required insulating value. Conventional materials include various types of fire bricks and super duty brick.
The coefficient of thermal expansion (CTE) for the selected material should not simply be assumed as a linear function for the materials used in the tunnel system. Having a fully characterized CTE is preferable for ensuring that the expansion behavior is properly managed. This becomes even more critical when the thermal expansion is managed on a single component level. Proper material selection preferably includes confirming that the modulus of rupture at the service and excursion temperatures of the furnace has a sufficient safety factor when compared to the associated static load stresses. Selecting a material with an improved HMOR provides immediate increases to the safety factor in the system. Knowing the room temperature MOR of a refractory material alone is not sufficient for proper design of a tunnel system.
In addition, any material being selected for use in a reformer furnace should preferably have the highest resistance to creep reasonably available, as a reduced creep will prolong the life of the tunnel system and prevent premature failures. The use of a material with improved creep resistance reduces the tension on the bottom side of the top lids, and reduces the outward force that the top lids exert onto the brick walls of the tunnel, which is preferred. Using a material having a fully characterized CTE, higher HMOR, and increased creep resistance together improves the overall reliability of the tunnel system.
In view of the above, in the present invention, suitable materials for the refractory inserts, refractory bricks (blocks), refractory bases, and refractory covers (lids) include, but are not limited to alumina-based refractory materials, cordierite (magnesium aluminum silicate), and zirconia, for example. More preferably, the blocks, lids and bases are made from a material selected from the group consisting of medium duty fire clay brick (Oxide Bonded Alumina comprised of at least 30% alumina by weight), high duty fire clay brick (Oxide Bonded Alumina comprised of at least 35% alumina by weight), super duty fire clay brick (Oxide Bonded Alumina comprised of at least 40% alumina by weight), and high alumina fire clay brick (Oxide Bonded Alumina comprised of at least 60% alumina by weight). Most preferably, the present invention utilizes Mullite Bonded Alumina comprised of 88% alumina by weight or an Oxide Bonded Alumina comprised of 95% alumina by weight.
The refractory inserts according to the present invention could conceivably encompass any desired type of component, including but not limited to flow constricting/restricting plugs, flow directing cups and cradles for cross beam supports (i.e., tie bars), and can be easily added to the blocks (to define a block assembly) or removed from the blocks without limiting access to other tunnel components during turnarounds, ensuring that repairs can be complete and effective. Faster installation and repair time also allows for proper repairs to be made more readily, improving the overall reliability of the system.
The present invention takes into account the mechanical features with respect to the interaction between the orifice insert and the side block tabs, and utilizes the axial force imparted on the insert (in service) by the pressure drop of the flue gas passing through it, with the addition of an axial projection from the upstream wall of the channel of the insert, to prevent unwanted rotation leading to disassembly. This pressure typically ranges from 1 inch H2O to 10 inches H2O.
The retention mechanism according to present invention provides a discontinuity of the circumferential channel of the refractory insert at the end of the opening (slot) in the channel sidewall. This provides a definitive rotational stop for the insert as the channel discontinuity contacts the inserted tab from the block hole. One end of the opening includes a stop wall (rotational stop), and the other end includes an axial projection extending into the channel from the upstream inside wall of the channel, which narrows the gap to just permit the tab to pass therethrough upon the initial installation rotation, but which prevents counter-rotation.
The axial retention projection preferably extends from the upstream inside wall of the channel, and preferably has dimensions of 0.050″ to 0.200″. This retention projection member narrows the proximate channel axial width, effectively reducing the axial clearance between the sidewalls of the circumferential channel and the tabs to a minimal level that will still allow for rotation upon installation. This clearance ranges from 0.010″ to 0.020″.
The refractory insert is oriented so that the slots in the sidewall of the channel align with the tabs, and is installed from the downstream side of the block, ensuring that the retention projection is oriented (faces) upstream. The refractory insert is inserted into the hole of the block axially until the tabs of the block (in the hole of the block) are in contact with the continuous downstream inside wall of the insert circumferential channel. The refractory insert is then rotated at least until the tabs of the block enter the openings of the channel and clear past the retention projections proximate thereto, after which the refractory insert is pulled axially in the direction of flue gas flow to seat the tabs in the channel in the space between the rotational stop and the retention projection. In operation, the force exerted by the pressure drop across the refractory insert will maintain this axial position. While it is not necessary, mortar and/or ceramic fiber could still be used for extra security, if desired.
The refractory inserts having the retention mechanism according to the present invention can be readily removed and or replaced with another refractory insert having a different configuration (i.e., a different central ring size opening or a solid puck) after the original installation, if it is deemed necessary by the end user to alter the flow dynamics. Providing universal, modular refractory inserts and refractory block assemblies that can be used in connection with any type of refractory block further enables end users to modify any tunnel system and custom tailor the flow dynamics according to their particular needs. The prior art fails to provide a refractory insert having such a retention mechanism
For a better understanding of the nature and object of the present invention, reference should be made to the following detailed description of a preferred mode of practicing the invention, read in connection with the accompanying drawings, in which:
It should also be noted that although blocks 1, 10 as shown do not include any through-holes, either type of block 1, 10 can be modified or manufactured to include one or more though-holes, as discussed below in connection with
Each of the bricks 1, 10 has an outer peripheral surface defining a first end (1a, 10a), an opposed second end (1b, 10b), an upper surface (1c, 10c) and an opposed lower (bottom) surface (1d, 10d). These bricks 1, 10 are hollowed out to remove all possible material from non-critical areas. Preferably, the wall thickness “t” (see, e.g.,
The upper surfaces 1c, 10c of the blocks 1, 10 each include a male part of the precision interlocking mechanical mating features of the refractory blocks according to the present invention. The protruding portion 3 is elevated a distance from the surface 1c, 10c to define a geometrical member that extends from the block 1, 10 and serves as a locking part that fits precisely into the opening 4 formed in the lower surface 1d, 10d of the blocks 1, 10. As shown, the protruding portion 3 is a substantially rectangular elevation with chamfered corners and a circular opening 3a passing through its center and in communication with a cavity 2. The circular opening 3a is merely a function of manufacturing and material removal considerations, and is not critical. As shown in
While the exact shape of the protruding portion 3 is not necessarily limited to the shape shown here, it is preferably a geometric match to the shape of the corresponding opening 4, with a slight off-set to accommodate manufacturing tolerances. The protruding portions 3 of the blocks 1, 10 must fit precisely within the openings 4 of the vertically adjacent blocks 1, 10 to securely engage the vertically adjacent blocks 1, 10 to one another to facilitate the construction of free-standing tunnel walls without the use of mortar. There must also be sufficient tolerance to account for the thermal expansion considerations discussed above, and to maintain contact to prevent buckling.
The opening 4 communicates with the cavities 2 of the blocks 1, 10, and receives the protruding portion 3 in a tight, interlocking manner to securely connect the blocks 1, 10 to one another, without mortar, in a vertically stacked manner, as shown in
The importance is the geometric match with a slight off-set between the corresponding protruding portion 3 and opening 4 into which the protruding portion 3 fits. Preferably, the off-set is in a range of 0.020 in to 0.060 in. The minimum off-set is dictated by manufacturing tolerance capabilities resulting in block to block variability. There must be sufficient height and tightness to securely engage if buckling occurs. Preferably, the overall height “h” of the protruding portion 3, or distance that the protruding portion 3 extends from the upper surface 1c, 10c of the blocks 1, 10, is at least 0.75 in, in order to ensure sufficient engagement with the opening 4 and prevent buckling. The dimensions of the opening 4 should be as tight to the protruding portion as possible with allowance for manufacturing variation. Ideally, uniform wall thickness balanced with manufacturing needs governs the dimensions.
The individual blocks 1, 10 further include additional mechanical mating features, such as a tab on one end and a groove on the other end, with a gap provided that allows each block to expand with increasing operating temperature until its seals against the blocks on either side thereof in the horizontal arrangement direction. As shown in
A compressible high temperature insulation fiber (not shown) can also be provided, placed in the groove 5 in order to reduce gas bypass while accommodating for a range of temperature fluctuations in service. The fiber is specified to have sufficient compression variability so as to reduce gas bypass over a wide range of operating temperatures from 600° C.-1200° C. This fiber can also be used in between layers of blocks to prevent point loading. As discussed below, the base components and top lids (covers) both have a similar tab and groove design, and use either a fiber gasket or a fiber braid to reduce gas bypass over the range of operating temperatures.
Preferably, as the blocks 1, 10 are arranged in the formation of the tunnel wall, the blocks 1, 10 are horizontally off-set by one-half of a block length, or by one set of mechanical mating features, to increase the mechanical robustness of the arrangement (see, e.g.,
The mechanical mating features described above add redundancy to the system by mechanically engaging the blocks, which prevents the tunnel wall from leaning and falling over without requiring that mating features be sheared off or otherwise break through the wall of the block to which they are connected.
In order for the tunnel to properly act as a flue for the exit of the furnace, it must have variable inlet conditions (openings in the walls), for example, which typically allow more gas to enter the tunnel farthest from the exit, and less gas to enter the tunnel closer to the exit (or in any manner dictated by the processing concerns). The typical arrangement creates a more uniform distribution of gas and temperature in the furnace. As noted above, conventional tunnel wall designs simply utilize half bricks to create gaps in the walls as various locations. However, such conventional half bricks create unsupported locations on top of the square openings, creating locations for failures.
As shown in
The block 100 has an outer peripheral surface defining a first end 100a, an opposed second end 100b, an upper surface 100c, and an opposed lower (bottom) surface 100d. Although a full block 100 is shown, it should be understood that a half-block could also be used, which would be the same as block 100, but only half the size (see, e.g., the description in connection with
Preferably, as the blocks 100 are arranged in the formation of the tunnel wall, the blocks 100 are horizontally off-set by one-half of a block length, or by one set of mechanical mating features, to increase the mechanical robustness of the arrangement (see, e.g.,
The through-holes 7 of the blocks 100 can have any geometry, but preferably have a circular or semi-circular shape. The size of the through-holes 7 can vary from 1 in2 up to substantially to the full size of the block 100, which is typically around 144 in2, but are preferably 12 in2-36 in2. For example, in
As shown in
A mechanical mating member, such as one or more tabs 8, are provided on the inner surface 7a (i.e., inner diameter; see
Refractory inserts having the retention mechanism according to the present invention are shown and described in connection with
As shown in
The downstream surface 302 includes an inner surface 302B (facing upstream) and an outer surface (facing downstream) 302C. An inner peripheral sidewall 302A extends between the downstream surface 302 and an inner surface 303B of the upstream surface 301.
The upstream surface 301 includes an outer surface (upstream side) 303A and an opposed inner surface (downstream side) 303B. The upstream surface 301 also includes a central opening 304 passing between the outer surface 303A and the inner surface 303B thereof. The size of the opening 304 can vary in diameter, depending on the desired gas flow characteristics. Typically, the opening is dimensioned to be in a range of 0.25-3″. The central opening 304 of the refractory insert 300 is smaller than that of the refractory insert 330 shown in
Slots 305 are formed in diametrically opposed locations on a sidewall of the refractory insert defining the channel 306, preferably the downstream surface 301, and are sized to permit the tabs 8, 81 of the blocks 100, 200 to fit therein and be accepted into the circumferential channel 306 when the refractory insert 300 is rotated upon installation. Preferably, the dimensions of the slots 305 are 60°. The circumferential channel 306 is defined by an opening 305A of the slot 305 at one end (i.e., a first end) of the channel 306, and a rotational stop 307 at the other end (i.e., a second end) thereof, so that the rotational stop 307 is interposed between the second end of the channel 306 and the opposed slot 305. The retention projection 308 is provided proximate the opening of the slot 305. Preferably, the length of the channel 306 is in a range of 62-120° and the width of the channel is in a range of 0.25-0.75″ (based on tab dimensions). As shown in
As noted above, the retention projection 308 extends axially from the upstream inside wall (sidewall) 303A of the first surface 301 defining the channel 306, and preferably has dimensions of 0.050″ to 0.200″. This retention projection 308 narrows the proximate axial width of the channel 306, effectively reducing the axial clearance between the sidewalls of the circumferential channel 306 (i.e., the inner wall 303 B of the surface 302 and outer surface 302B of surface 302) and the tabs 8, 81 to the minimal level that will still allow for rotation. This clearance ranges from 0.010″ to 0.020″.
In the refractory insert 300, at least one notch 309, preferably two diametrically opposed installation notches 309, are provided in the outer surface 302C of the downstream surface 302 and along a portion of the sidewall 302A to facilitate rotation of the refractory insert upon installation. An installation tool (not shown) having a T-shaped body is used to engage the two notches 309 and rotate the refractory insert into place in the through-hole 7, 71 of a refractory block 100, 200, as shown in
Upon installation, the refractory insert 300 is positioned so that the slots 305 align with the tabs 8, 81 of the respective block 100, 200. As the refractory insert 300 is rotated, the tabs 8, 81 positioned within the slot 305 will tightly pass the retention projection 308 and then reside within a portion of the circumferential channel 306 between the retention projection 308 and the rotational stop 307. Counter-rotation is not permitted by virtue of the tight dimensional tolerances of the retention projection 308, and over-rotation is prevented by the presence of the rotational stop 307. Even when the system experiences a pressure drop, the refractory insert is held in place, as-inserted, and will not be forced out of position, even if mortar or fiber gaskets are not used.
Suitable materials for the refractory inserts, as well as refractory bricks (blocks), refractory bases, and refractory covers (lids), include, but are not limited to alumina-based refractory materials, cordierite (magnesium aluminum silicate), and zirconia, for example. More preferably, the refractory inserts, blocks, lids and bases are made from a material selected from the group consisting of medium duty fire clay brick (Oxide Bonded Alumina comprised of at least 30% alumina by weight), high duty fire clay brick (Oxide Bonded Alumina comprised of at least 35% alumina by weight), super duty fire clay brick (Oxide Bonded Alumina comprised of at least 40% alumina by weight), and high alumina fire clay brick (Oxide Bonded Alumina comprised of at least 60% alumina by weight). Most preferably, the present invention utilizes Mullite Bonded Alumina comprised of 88% alumina by weight or an Oxide Bonded Alumina comprised of 95% alumina by weight.
A tunnel assembly is provided by combining refractory blocks, refractory inserts and other structural members, such as base members and lids. Any type of block, base and lid can be used in connection with the tunnel assembly including refractory inserts having the retention mechanism according to the present invention. An example of a preferred base component 30 used to form a tunnel assembly is shown in
Each base component 30 has an outer peripheral surface with an upper surface 30c and an opposed lower (bottom) surface 30d on which the interlocking mechanical mating features protruding portions 33, and corresponding openings 34 (not shown) are respectively formed. The protruding portions 33 correspond to the protruding portions 3 described above in connection with the bocks 1, 10, 100, and the openings 34 correspond to the openings 4 described above in connection with the blocks 1, 10, 100. The same critical dimensional requirements for the mechanical mating members and wall thicknesses discussed above apply to the base components, as well. Preferably, each base component 30 has a total weight in a range of about 60-100 lbs., more preferably less than about 70 lbs.
The protruding portions 33 are provided on the upper surface 30a of the base components 30 proximate the two opposed ends 30a, 30b, so as to correspond to the laterally (horizontally) opposed locations of the tunnel walls to be built thereon. The openings 34 are provided in the bottom surface 30d of the base component 30 in corresponding locations. In some embodiments, the base component 30 has a plurality of cavities from which unnecessary material has been removed to reduce the weight of the base block. The openings 32 are material removed portions and may or may not communicate with such cavities, and a plurality of additional cavities are provided along the length of the base component 30, separated by interior block walls having sufficient thickness to provide enough material to ensure the structural integrity of the component is maintained. The wall thickness is preferably in a range of 0.5 to 1.5 in, preferably 0.625 to 0.875 in.
As noted above, it is important that the size and material of the base component 30 is substantially the same as that of the lid (discussed in more detail below) in order to properly and effectively compensate for thermal and stress factors, although the base is a heavier component, as one skilled in the art can appreciate. Conventional base and lid members can also be used in connection with the blocks including the refractory inserts according to the present invention to form a tunnel assembly/system.
The lid 60 is also hollowed out from the bottom surface 60d to remove all possible material from non-critical areas, in order to minimize the stress by improving the ratio of force per unit area of the cross section. As shown in
The lids 60 also have additional mechanical mating features such as the grooves 65 formed on side surface 30f (see
As shown in
Additional blocks 1A, 100 are then alternately stacked onto one another, secured to one another vertically and horizontally, preferably without mortar, via the respective mechanical mating members 3, 4, 5 and 6, continuing in a half-block, off-set manner, to define two parallel, vertically oriented tunnel walls 8 that extend both in the second (i.e., vertical arrangement direction) from the base components 30 and in the longitudinal extension direction of the tunnel. As shown, some of the blocks correspond to the blocks 10 shown in
The tunnel walls 8 are spaced a predetermined distance (i.e., 12-60 in, preferably 24 to 36 in) apart from one another in the horizontal arrangement direction, dictated by the horizontal span of the base components 30. Tie bars 50 are inserted into refractory insert using tie bar cradles 15 in desired locations, as needed. Refractory inserts can also be inserted into the through-holes 7 of the blocks 100 in the any location that is desired to define refractory block assemblies at those points (see, e.g.,
As discussed above, in the tunnel 400/400A according to the present invention, reducing the weight of all of the components, while maintaining the structural integrity of each of the individual components, makes it possible to eliminate much of the crushing force on the lower courses of the brick (i.e., the base components 30). Providing light-weight, structurally correct cover (lid) components 60 overcomes the drawbacks previously associated with making conventional lids thicker in order to be stronger, which also detrimentally added additional load to the entire system. The incorporation of controlled expansion gaps between each brick and elimination of mortar from the overall system ensures that the tunnel assembly 400/400A can expand and contract without creating large cumulative stresses, and reduces the installation time of the tunnel assembly 400/400A as a whole.
With the reduced wall thickness and improved materials used for the components, the light-weight tunnel lids 60 can be easily installed or removed simply by two laborers. In addition, the light-weight, mortar-free blocks with interlocking mechanical mating features are easily handled by a single laborer, and the tunnel structure 400/400A can assembled, repaired and/or disassembled as necessary without significant consequences or the requirement for high levels of skill. Cross beam supports (i.e., tie bars 50 in respective cradle inserts 15), as well as other refractory inserts, can be easily added or removed from the blocks (block assemblies) in the tunnel assembly 400 without limiting access to other tunnel components during turnarounds, ensuring that repairs can be complete and effective.
The refractory inserts 300, 330 are held in place without the use of mortar by virtue of the retention mechanism according to the present invention, and the loss of refractory inserts during pressure drops is effectively prevented. Faster installation and repair time also allows for proper repairs to be made more readily, improving the overall reliability of the system.
While the present invention has been shown and described above with reference to specific examples, it should be understood by those skilled in the art that the present invention is in no way limited to these examples, and that variations and modifications can readily be made thereto without departing from the scope and spirit of the present invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US18/27451 | 4/13/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62485526 | Apr 2017 | US |
