insulating concrete shell

Description

[0001] The subject of this invention is an insulating concrete shell made of refractory cast concrete or refractory rammed concrete for insulating uprights or support pipes in a walking beam or pusher furnace. Such insulating concrete shells are shaped to completely encase the pipe to be insulated. Often, two semi-cylindrical insulating concrete shells are placed around a pipe for this purpose. However, since the pipes or uprights can also have an oval or rectangular cross-section, the shapes of the insulating concrete shells are adapted accordingly.

[0002] It is also conceivable that three or more insulating concrete shells are needed to completely encase a pipe or a column.

[0003] The present insulating concrete shell has a metal strip on the inside at each end, via which the insulating concrete shell is attached to the upright or the support tube.

[0004] The subject matter of this invention also includes a method for producing an insulating concrete shell.

[0005] In heat treatment furnaces such as walking beam or pusher furnaces, water- or steam-cooled support tubes or uprights are frequently used to support the metal workpieces during heat treatment. To reduce heat loss from the furnace due to tube cooling, the tubes are fitted with suitable insulating sleeves made of ceramic or refractory material. The service life of this tube insulation is limited, so the furnaces are shut down at regular intervals and the insulation is replaced.

[0006] Conventional insulating concrete shells have a rolled sheet on the inside adapted to the pipe diameter of the support pipe system (see Figures 1 and 2A series of anchors (slotted pins) 2 are welded to the sheet metal 1. A ceramic fiber mat 3 is placed on the rolled sheet metal 1, and the slotted pins 2 protruding through the fiber mat 3 are spread open, thus holding the fiber mat 3 to the sheet metal 1.

[0007] The ceramic fiber mat 3 serves to reduce the thermal conductivity of the insulating concrete shell 5.

[0008] The casing of the insulating concrete shell 5 is then made from cast or tamped refractory concrete 4. The sheet metal 1 and the anchors (2) contribute significantly to the strength of the insulating concrete shell 5.

[0009] An insulating concrete shell according to the state of the art is also described in WO 2010 / 131213.

[0010] For the assembly of the insulating concrete shells, the rolled sheet metal 1 is then attached to the support tubes or uprights of the oven, for example by welding or screwing.

[0011] The following problems occur with conventional insulating concrete shells: The numerous anchors (slotted pins) welded to the sheet metal result in increased thermal conductivity compared to applications without such anchors. During the casting process, the ceramic fiber mat is contaminated (infiltrated) with the casting water and compressed, further increasing its thermal conductivity.

[0012] DE 8 407 841 U1 discloses a refractory casing for elongated components in furnaces made of mineral or ceramic fibers. This casing also includes two arc-shaped supports, which have two narrow, approximately semicircular, hinge-like retaining brackets.

[0013] German patent DE 2354883 discloses a semi-cylindrical insulating concrete shell made of a ceramic material. In contrast to the insulating concrete shell described above, this shell incorporates only two internal metal bands, which interlock the two insulating concrete shells. V-shaped reinforcing elements (anchors) made of corrosion-resistant steel are welded to these bands. The two bands and the reinforcing elements are encased in the ceramic material. While the use of two narrow metal bands instead of a large sheet and the reduced number of reinforcing elements keep the thermal conductivity of the insulating concrete shell low, the absence of a metallic support structure results in reduced mechanical stability.

[0014] The invention is therefore based on the objective of providing an insulating concrete shell that should have, on the one hand, the lowest possible thermal conductivity and, on the other hand, the greatest possible stability.

[0015] This problem is solved by an insulating concrete shell according to claim 1. In the insulating concrete shell according to the invention, the two sheet metal strips bent into a semicircle are connected to each other by wires, wherein the two wires are completely embedded in the cast or rammed concrete.

[0016] The use of sheet metal strips significantly reduces the thermal conductivity of the insulated concrete shells compared to insulated concrete shells with a continuous sheet metal casing. Connecting the two sheet metal strips via wires also keeps the thermal conductivity low and, in addition, ensures good stability of the insulated concrete shell. Preferably, the sheet metal strips are connected to each other via two wires, which may have an elongated U-shape.

[0017] It is very advantageous if the wires are only welded to the metal strips at their ends. This results in a very small contact area with the metal strips and therefore low thermal conductivity.

[0018] Preferably, cross wires are attached along the wires so that the two metal strips are connected to each other via grid-like wire anchors. This increases the stability of the insulating concrete shell.

[0019] According to the invention, a recess is located on the inside of the insulating concrete shell in the area between the two metal strips, into which a fiber mat is inserted. The inserted fiber mat increases the insulating capacity. Furthermore, this design allows the fiber mat to be inserted only after the casting / tamping process and after hardening, so that the fiber mat can no longer be damaged by the casting water.

[0020] The invention also relates to a method for producing an insulating concrete shell, comprising the following steps: Two strips of sheet metal are bent to match the shape of a post or support tube so that they can be fitted to the post or support tube during subsequent assembly; the two bent strips are connected by at least two wires; the connected strips are placed in a mold or die with a recess, which may be semi-cylindrical, for example, on the inside between the two strips; the mold or die is filled with refractory concrete; after hardening, the manufactured component is removed from the mold; a ceramic fiber mat is inserted into the recess on the inside.

[0021] The inserted ceramic fiber mat can no longer be deformed by the water-containing refractory concrete, thus further improving the insulating properties.

[0022] The prior art and an embodiment of the invention are described below with reference to the drawings. These show: Fig. 1 a schematic cross-section through an insulating concrete shell according to the state of the art; Fig. 2 a longitudinal section through the insulating concrete shell made of Figure 1 ; Fig. 3 a schematic cross-section through an embodiment of an insulating concrete shell according to the invention; Fig. 4 a longitudinal section through the insulating concrete shell made of Figure 3 ; Fig. 5 a perspective view of the insulating concrete shell according to the invention;

[0023] Identical reference symbols in each figure denote identical elements.

[0024] The in Figures 1 and 2 The insulating concrete shell 5 shown represents a design according to the state of the art, as already explained in the introduction above.

[0025] In Figure 3A cross-section of an insulating concrete shell 5 according to the invention is now shown. Figure 4 shows a side section view of the insulating concrete shell 5 made of Figure 1 .

[0026] On the inner side 10a, two sheet metal strips 1a, bent into a semicircle, are visible. Two wires 6a are welded to the sheet metal strips 1a. The two wires 6a are bent into a U-shape and welded to the sheet metal strips 6a at their ends 11a. Transverse wires 7a are attached along the wires 6a; in this embodiment, they extend essentially circumferentially around the insulating concrete shell 5a. The wires 6a and the transverse wires 7a form grid-like wire anchors 2a. The wires 6a and the transverse wires 7a are embedded in cast or rammed concrete 4a. On the inner side 10a, in the area between the sheet metal strips 6a, a recess 8a is provided in the cast or rammed concrete 4a. A ceramic fiber mat 3a is inserted into this recess 8a. The U-shape of the wires 6a is in Figure 5 clearly visible. Reference sign

[0027] 1Sheet metal 2Anchors (slotted pins) 3Fiber mat 4Cast / rammed concrete 5Insulating concrete shell 1aSheet metal strip 2aWire anchors 3aFiber mat 4aCast / rammed concrete 5aInsulating concrete shell 6aWires 7aCross wires 8aRecess 10aInside 11aWire end

Claims

1. Insulating concrete shell (5a) made of refractory cast concrete or of refractory tamped concrete (4a) for insulating uprights or supporting tubes in a walking beam furnace or pusher-type furnace, wherein the insulating concrete shell (5a) is shell-shaped and a respective sheet metal strip (1a), bent into a semicircle, is arranged on the inner side (10a) at the respective end of the insulating concrete shell (5a) for fastening the insulating concrete shell (5a) to an upright or to a supporting tube, characterised in that the two sheet metal strips (1a) are connected to one another by wires (6a) and in that the two wires (6a) are completely embedded in the cast or tamped concrete (4a), wherein on the inner side (10a) of the insulating concrete shell (5a) in the area between the two sheet metal strips (1a) there is a recess (8a) into which a fibre mat (3a) is inserted.

2. Insulating concrete shell (5a) according to claim 1, characterised in that the wires (6a) are welded at their ends (11a) to the sheet metal strips (1a).

3. Insulating concrete shell (5a) according to claim 1 or 2, characterised in that the two sheet metal strips (6a) are connected to each other by two wires (6a).

4. Insulating concrete shell (5a) according to one of claims 1 to 3, characterised in that the wires (6a) are bent in U-shape.

5. Insulating concrete shell (5a) according to one of claims 1 to 4, characterised in that cross wires (7a) are fixed along the wires (6a) so that the two sheet metal strips (1a) are connected to each other via grid-like wire anchors (2a).

6. Insulating concrete shell (5a) according to claim 5, characterised in that the cross wires (6a) are completely embedded in the cast or tamped concrete (4a).

7. Method of producing a shell-shaped insulating concrete shell (5a), comprising the following steps: - two sheet metal strips (1a) are semicircle bent according to the shape of an upright or a supporting tube; - the two bent sheet metal strips (1a) are connected by at least two wires (6a); - the interconnected sheet metal strips (1a) are placed in a casting or tamping mould, this mould enabling the production of a substantially shell-shaped component with a recess (8a) on the inner side (10a) between the two sheet metal strips (1a); - the casting or tamping mould is (4a) filled with refractory concrete; - after curing, the manufactured component is removed from the mould; - a ceramic fibre mat (3a) is inserted into the recess (8a) at the inner side (10a).