A STRUCTURE FOR BEARING INSULATING MATERIAL, IN PARTICULAR FOR THE THERMOINSULATION OF HOT AND WIDE SURFACES

Abstract: The structure comprises a supporting spacer consisting of a plurality of vertical sections or rods (1) slidingly retained onto the hot surface by means of stirrups (3), and outer finishing sheet metal elements (13) provided with supporting horizontal guides or rails. The rods (1) further comprise shaped plates adapted to slidingly engage with said horizontal guides mounted secured on the elements (13). The structure of the invention allows uninterrupted sheet metal elements to be used for the insulation of flat and curve hot surfaces, any deformation, detachment or breakage of the finishing insulating elements due to the inner stres­ ses in the structure being avoided.

Description: The present invention relates to an insulation material bearing structure, in particular for the thermoinsulation of hot and wide surfaces, according to the preamble of claim 1. The thermoinsulation of the outer walls of storage tanks, stacks, heat exchangers and similar apparatuses with working temperatures ranging from 500° to 650°C is conventionally carried out by means of outer finishing sheet metal elements stiffly secured to the hot walls and mounted in a spaced position from the latter by means of supporting carpentry. It is, however, known that any body undergoing increasing temperatures will deform according to the thermal expansion coefficient thereof. The sheet metal elements of the aforementioned insulating structure will thus deform owing to a double effect: firstly due to the hot wall dilations transferred through the supporting carpentry to the sheet metal elements rigidly secured to both the hot surface and said sheet metal elements, and secondly due to the flow of heat transmitted outwardly through said carpentry acting as a thermal bridge, latter deformation being very important on account of the expansion coefficient of the sheet metal material. The insulating material generally used in support of the insulating structure and suitable for high temperatures is further subjected to contraction, thus increasing the disadvantages due to the hot surface expansion. Breaks in the connecting members resulting from deformation stresses are the main damage caused to the sheet metal elements, the temperature of which is considerably increased due to the presence of thermic bridges, the latter further causing a loss of heat. Accordingly, in addition to the deformation caused by direct heating of these surfaces, the problem exists of protecting and safeguarding the plant staff. US-A-2 435 172 (YOUNG) relates to a stack for furnaces, providing a framework for the support of outer walls mounted in a spaced relationship in respect of an inner refractory wall. US-A-4 369 032 (LOWRANCE) describes a reheat furnace comprising a plurality of resilient means to avoid overloading of a rigid frame mounted on refractory elements. GB-A-829 201 ( LACLEDE-CHRISTY CO) relates to suspended refractory linings for furnaces. FR-A-1 413 235 (DIDIER-WERKE AG) describes the construction of walls for furnaces. All aforementioned documents show different solutions to the problem of expansion and contraction of metal framework as a result of the furnace heat. Said prior art has the main disadvantage that the metal framework structure needs to be protected from the high furnace temperature (600° - 700°C) as well as requiring air cooling in order to avoid the metal members from sliding into contact, binding and breaking. According to the teachings of said prior art, the metal framework is secured to a layer of heavy and rigid refractory material, thereby assuming a marked degree of stiffness. The above known insulating structures also require a suitable foundation for supporting the metallic framework, not allowing for the use of flexible insulating material (e.g. mineral wool and aluminium foils) and generally being very complex and expensive. DE-A-3 032 359 (LOOS) and LU-A-68 748 (BPB INDUSTRIES LTD) describe metal structures for supporting coat members of building walls. The insulation material bearing structure as described in document LU-A-68748 includes a rail mounted horizontally on the hot surface. Within the rail, a spacer is so arranged as to slide in horizontal direction, whereas on the side of the spacer facing away from the rail, a groove is formed, extending in vertical direction. Within the groove is a vertical sliding rail, bearing the outer finishing sheet elements. The insulation material bearing structure as shown in document LU-A-68 748 is suitable for mounting cover means on the walls of buildings and for receiving the expansion of material as caused by atmospheric temperature or sunlight. Although said support structures may be advantageously used at low temperatures (ranging within room temperature), they are obviously inadequate in view of temperature increases such as in furnaces or heat exchangers. In fact, the connecting elements of the structure are quickly prone to deformation as a result of high temperatures and are generally adapted for mounting on flat walls only. It is the object underlying the present invention to provide an insulation material bearing structure adapted to overcome the limitations inherent to the known outer insulation material bearing structures, as stated. The object is achieved by the features of claim 1. With the bearing structure according to the present invention, the stirrup and hot surface directly engage each other; concomitantly, dimensional movement of said stirrup and hot surface due to thermal expansion of the latter is allowed for whilst keeping said insulating sheet metal elements in a stationery position. The means for accommodating dimensional movement of the structure of the invention consist of a plurality of vertical sections or rods provided on one side with connecting devices for engaging said sheet metal elements as well as allowing for horizontal displacement of said rods in respect of said sheet metal elements and, on the other side, with brackets or stirrups for the engagement of the hot surface in vertical sliding relation to same bearing structure. According to a further development of the invention, horizontal support guides or rails secured to said sheet metal elements are provided, the guides as stated interacting with the relevant engaging means of the rods. In accordance with a particular embodiment of the invention suitable for the purpose of thermoinsulating flat and wide surfaces, the aforementioned means adapted to connect said rods and sheet metal elements consist of essentially C cross-sectioned plates, the lower end of which is provided with an outer vertical stop, said plates further comprising a plurality of rolling contact bearings mounted on the vertical and lower horizontal sides of said C cross-sections, said bearings permitting said horizontal guides of the sheet metal elements to slide within the shaped plates of the rods, as mentioned. Said means for connecting said rods and sheet metal elements, as stated, consist - in accordance with a characteristic embodiment of the invention particularly adapted to the thermoinsulation of curved surfaces - of shaped metal plates in sliding engagement with said support guides of the outer sheet metal elements; resilient means can further be provided to allow for variations in the distance between said rods and said sheet metal elements due to the radially directed thermal expansion of the hot surface. As compared to known outer thermoinsulating structures comprising sheet metal elements, the invention shows the distinct advantage of allowing for thermal expansion and contraction of the hot surfaces to be insulated by means of a particular connection between the rods of the bearing structure and the same outer sheet metal elements. Such characteristic connection permits the use of outer sheet metal elements having a continuous surface to thermoinsulate flat and curved hot surfaces, preventing any inner stress capable of deforming, detaching or breaking the outer sheet metal elements. An additional advantage of the structure of the invention can be seen in that the heat dispersion through thermic bridges can be markedly reduced by making the cross section of the bearing of the structure of the invention small and by making use of light material for the vertical sections which are adapted to increase the course of the heat flow as outwardly directed. The layers of thermoinsulating material suitably arranged within the structure of the invention keep the heat transfer to a minimum, thus further diminishing heat dispersion. In comparison with the aforementioned documents, the present invention shows the advantage of the supporting structure resisting high temperatures, accordingly being mounted on the hot wall being insulated without any intermediate layer of refractory material being required. Consequently, the structure of the invention allows for a higher degree of deformation in all directions and, thus, may work at higher temperatures than the conventional structures. The invention shall hereinafter be described with reference to the accompanying drawings of some of the particular embodiments of same invention. Figure 1 is a perspective view illustrating a first embodiment of the bearing structure of the invention. Figure 2 is a front view of a shaped plate mounted on the upper portion of a vertical rod of the structure of fig. 1. Figure 3 is a horizontal, sectional view of the structure of fig. 1. Figure 4 is a sectional view along line A-A as shown in fig. 3. Figure 5 is a front view of a shaped plate mounted on the lower portion of a vertical rod of the structure of fig. 1. Figure 6 is a top plan view of a further embodiment of the structure of the invention. Figure 7 is a top plan view of the engaging means of the structure of fig. 6. Figure 8 is a side view of the elements of fig. 7. The bearing structure as shown in figures 1 to 5 is particularly suitable for the thermoinsulation of flat surfaces with the one as shown in fig. 6 to 8 having been adapted to thermoinsulate curved surfaces (e.g. the outer walls of storage tanks and converters). With reference to the embodiment of fig. 1 to 5, the bearing structure of the invention essentially consists of a supporting spacer and outer finishing sheet metal elements. The supporting spacer comprises a plurality of vertical sections or rods 1 made of metallic material and mounted in a parallel manner in front of the hot surface to be insulated 2. The side of said rods facing said surface 2 comprises a plurality of supporting brackets or stirrups 3 (fig. 3 and 4), the one wide of which is welded on the surface 2 itself whereas the opposite side of the brackets are secured to the rods 1 by means of grooved, smalls disks which mounted slidingly in a corresponding slit provided on the side of rod 1 facing the hot surface 2. Gaskets of ceramic material 5 are arranged interposed between the components of the stirrup 3 and the relevant disk 4 to reduce the heat transfer towards the bearing structure. On the opposite side of the rods 1, at least one shaped plate 6 is secured, preferably to the upper portion of each rod. The plates 6 are made of metallic C cross-sectioned elements (fig. 4), the lower end of which comprise an outer vertical member 7. The vertical side 8 of the plates is provided with two rolling contact bearings 9, mounted horizontally and aligned, the axis of rotation of which being perpendicularly directed to the axis of rod 1 carrying said plates. Each of the bearings 9 further comprises a peripheral groove 10. The lower horizontal side 11 of the plates 6, however, is equipped with a rolling contact bearing 12, the axis of rotation of which is directed in a parallel manner to the axis of the corresponding rod 1. The outer finishing sheet metal element comprises a corrugated sheet 13 made of aluminium, the inner side of which faces the plates 6 (and which is mounted at the same height), being provided with a supporting metal guide or rail 14. The latter essentially consists of a shaped metal section (approximately G cross-sectioned) (fig. 4), the upper end 15 of which is positioned upon assembly of the structure in groove 10 of the bearings 9, the lower and reverse base 16 thereof, however, being mounted on the inner side of the vertical member 7. The assembly of sheet metal elements 13, equipped with rails 14, on the vertical rods 1 are carried out by running the rail ends within the plates 6, the upper end of which is supported along grooves 10 of the bearings 9; the lower base 16 of the plate 6 being mounted on the member 7 of said plates 6. The bearing 12 with a vertical axis of rotation is mounted on the corresponding plate in such a way that the outer edge of said bearing protrudes from the body plate; the weight of the sheet metal element 13 which is retained by engagement of the shaped elements of the plates 6 with the rails 14 will thus partly be supported by the bearings 12, the latter maintaining said sheet metal element in vertical position and thereby drastically eliminating sliding friction. The supporting plate 17 of fig. 5 as mounted on the lower portion of the rods 1 differs from plate 6, as previously described, by lacking bearings as well as having a differently sectioned shape. Said plate 17 acts as a fixed point within the support structure and guides the thermal expansion of the structure in the desired direction. The thermal insulating material 18 ( flexible ceramic fibers and mineral wool) is positioned in the hollow space between the hot surface 2 and the sheet metal element 13. The vertical expansion of the hot surface 2 is accommodated by means of a sliding fit between the brackets 3 and the rods 1; the sheet metal elements 13 not being influenced by the horizontal displacement of the surface 2 (and subsequently of the rods 1) due to the particular sliding fit between the plates 6 and the supporting rails 14. The embodiment of fig. 6 to 8 relates to a curved hot surface 2. As in the previously described embodiment, the bearing structure 2 is provided with rods 1 and mounted in front of the surface 2 and retained in that position by means of brackets 3 and the relevant small, grooved disks 4. Similarly, the side of the rods 1 facing the sheet metal element 13 comprises C-shaped plates 19, similar to the plates 6 as already described but lacking any retaining members and bearings. The sheet metal element 13 carries horizontal guide means mounted at the same height as plates 19 and adapted to slide along the latter. Said guide means consist of light lattice beams 20 horizontally secured to the sheet metal element 13; the portion of said lattice beam 20 engaging plates 19 of the rods 1 being covered by plates 21. Telescopic spring members 22, allowing for radial displacement of the bearing structure relative to the elements 13, are provided to avoid the sheet metal element 13 disengaging from the structure of the rods 1. As in the previous embodiment, the hollow space between the surface 2 and the sheet metal element 13 is filled with thermal insulating material. Both of the aforementioned embodiments may comprise a single sheet metal element with an uninterrupted and smooth surface; nonetheless, the dimensional movement of the hot surface is not transmitted to the outer sheet metal element (which is kept in a stationery position in respect of the relevant support structure).

Claims: 1. Insulation material bearing structure for hot and wide surfaces (2) of stacks, heat exchangers and the like, comprising a plurality of first connecting devices (3, 4) for supporting a spacer (1) on said hot surface (2) so as to be slidable relative to said hot surface along a first sliding direction, a plurality of second connecting devices (6) for supporting outer finishing sheet metal elements (13) on said spacer (1) such as to be slidable relative to said spacer (1) along a second sliding direction perpendicular to the first sliding direction, characterised in that said spacer is a vertical rod (1) having a longitudinal slit provided at its side opposed to the hot surface (2); and that each of said first connecting devices comprises a stirrup (3) secured to the hot surface (2) and supporting a disk (4), slidably housed within said longitudinal slit of said vertical rod (1), wherein gaskets (5) are interposed between said stirrup (3) and said vertical rod (1) to reduce the heat dispersions from the hot surface ( 2) to the bearing structure. 2. A structure as claimed in claim 1, wherein said second connecting devices consist of shaped plates (6), connecting, for free horizontal displacement, said supporting guides (14) of the sheet metal elements (13) and said rods (1). 3. A structure as claimed in claim 2, wherein shaped plates (17) acting on said sheet metal elements (13) are further provided, said plates (17) acting as a fixed point of the said structure in the horizontal plane to guide the displacement of the structure in predetermined directions. 4. A structure as claimed in claim 2, wherein said shaped plates (6) are of C cross-section having an outer vertical stop (7) provided at the lower end (11) of said cross-section, said plates ( 6) further comprising a plurality of rolling contact bearings (9, 12), mounted respectively on the vertical (8) and lower horizontal sides (11) of said C cross-section, said bearings enabling said horizontal guides (14, 15) of the sheet metal elements (13) to slide within the shaped plates (6). 5. A structure as claimed in claim 4, wherein a groove (10) is provided on the outer peripheral surface of said bearings (9) engaging said guides (14, 15) of the outer sheet metal elements (13) . 6. A structure as claimed in claim 5, wherein said supporting metal guides consist of shaped horizontal sections (14), the shape thereof being complementary to that of the aforementioned rod plates (6) by which they engage each other, said sections (14) being of substantially G cross section, the upper end (15) thereof being positioned within said groove (10) of the bearings (9), the lower base (16) thereof being set against said stop (7) of the shaped plates (6), a layer of flexible insulating material (18) being filled into the hollow space between said hot surface (2) and the sheet metal element (13). 7. A structure as claimed in claim 1, wherein said second connecting devices consist of shaped plates (19) which slidingly connect supporting guides (21) of the aforementioned outer sheet metal elements (13), and resilient means (22) suitable for accommodating variations in distance between said rods and sheet metal elements (13), said variations being due to the radially directed thermal expansions of the hot curved surface. 8. A structure as claimed in claim 7, wherein said resilient means consist of telescopic spring members (22) secured on one side of said spacers (1) and to the sheet metal elements (13) on the other, said horizontal supporting guides consisting of light lattice beams (20) having protective stirrups (21) on the surface to engage said shaped plates (19) of said rods (1), a layer of flexible insulating material (18) being placed within the hollow space between said hot surface (2) and the sheet metal element (13).

Inventors: ZICCARDI, ALBERTO
Applicants: ZICCARDI, ALBERTO
Application year: 1987
Main classification: F23M5
IPC codes: F27D1, E04H12, E04F13