GB2159612A

GB2159612A - Furnace lining components

Info

Publication number: GB2159612A
Application number: GB08513194A
Authority: GB
Inventors: Jurgen Steinborn; Norbert Meyer; Hans Steinborn
Original assignee: Didier Werke AG
Current assignee: Didier Werke AG
Priority date: 1984-05-25
Filing date: 1985-05-24
Publication date: 1985-12-04
Also published as: BE902487A; FR2564959A1; IT1183648B; GB2159612B; DE3419540C1; IT8520829A0; GB8513194D0

Abstract

A component for lining an electrically heated furnace includes a plurality of layers 1,3,4,5,6,7 and 8 of insulating material and at least one support sleeve 10 of ceramic material screwed into a bore 9 passing through the layer 1 which will form the inner surface of the lining but extending through only a part of the thickness of the component. One end of the sleeve 10 projects proud of the layer 1 portion of the sleeve between the and terminates with a head 14 the layer 1 and the head 14 constituting a support member 13 for an electrical heating element 21. The component also includes an anchor peg 20 having one end located in the sleeve 10 and its other end screwed into a threaded member 19 disposed at the opposite side of the component to the layer 1. <IMAGE>

Description

SPECIFICATION Insulating components The invention relates to an insulating component for the lining of an electrically heated furnace and is concerned with that type of such component which includes a plurality of insulating layers and at least one support member for mounting an electrical heating element, such as a heating strip or heating coil, adjacent, i.e. in front of that layer of the component which, in use, forms the inner surface of the furnace.

Such an insulating component is described in German Patent Application P 3314760.4.

In this application the support members are afforded by straps which are suspended from rods supported by retaining anchors on the insulating components and are not anchored to them. The rods and the straps must be installed during the assembly of the insulating components in the furnace which prolongs the assembly time.

In order to be able to mount heating elements adjacent the interior surface of the furnace it is known to provide special support bricks between the insulating components.

The support bricks are expensive and worse than insulating components of ceramic fibres as regards their thermal shock resistance and insulating properties.

It has been proposed that channels be constructed on lining blocks of fibre material into which a heating coil or a heating strip may be laid. Such channels tend to break off and are expensive to manufacture. They also reduce the electrical efficiency of the heating elements within them.

It is the object of the invention to provide an insulating component of the type referred to above in which the support members are anchored to the insulating component itself.

In accordance with the invention there is provided an insulating component for the lining of an electrically heated furnace including a plurality of layers of insulating material and at least one support sleeve of refractory material which is received in a respective bore which extends through that layer which will form the inner surface of the furnace but extends over only a part of the depth of the component, one end of the or each support sleeve projecting proud of the said layer and carrying a head spaced from the said layer, that portion of the or each support sleeve between the said layer and the associated head constituting a support member for supporting an electrical heating element, the component also including an anchor peg associated with the or each support sleeve of which one end is located with respect to the associated support sleeve and the other end is screw threadedly connected to an opposing member disposed on the side of the component remote from the said layer.

Preferably the or each support sleeve has an external screw thread and is screwed into the associated bore.

The or each support sleeve is thus anchored in the insulating component in two different ways. On the one hand it is retained in its bore in the insulating component by its external thread. On the other hand it is also fixed in position in the insulating component by means of the associated anchor peg. It is therefore ensured that the support sleeve will not fall out of the insulating component when the direct screw connection between the support sleeve and the component becomes worn or damaged during operation of the furnace.

It is thus ensured that the heating element can not fall off the support members of the support sleeves.

The diameter of the anchor peg is preferably substantially smaller than that of the support sleeve. It thus scarcely affects the integrity of the insulating component and can be easily installed.

In a preferred embodiment of the invention a spacer disc is arranged on the or each support sleeve which engages the said layer of the insulating component which will form the inner surface of the firnace. The support member is then constituted by the portion between the spacer disc and the head. The spacer disc ensures that the heating element is maintained at a certain distance from the insulating component.

The invention also embraces an electrically heated furnace insulated by a lining comprising a plurality of such insulating components.

Further features and details of the invention will be apparent from the following description of one exemplary embodiment which is given by way of example with reference to the accompanying drawings, in which: Figure 1 is a sectional elevation of an insulating component; Figure la is a view in the direction of the arrow la in Fig. 1; Figure 2 is a front view of a plurality of such insulating components together with a heating strip carried by them, shown on a reduced scale by comparison with Fig. 1; and Figure 3 is a sectional view on the line Ill-Ill in Fig. 2.

The insulating component or block includes a preformed layer 1 which is manufactured from ceramic fibre material and is of stable shape and is constructed in the manner of a bowl or shell. Its base surface 2 is directed in use, towards the interior of the furnace to be lined with such insulating components and the layer is thus referred to as an inner layer.

A plurality of insulating layers, namely two insulating plates 3 and 4 and three insulating mats 5, 6 and 7 are received in the space defined by the inner layer 1. The insulating plates and mats all comprise a ceramic fibre material. The insulating plates 3 and 4 contain an organic bonder which vaporises at about 1 60 C whereafter the insulating plates expand (superfelt plates) as a consequence of the internal stressing of the ceramic fibres.

The insulating mats 5, 6 and 7 contain no bonder (blanket mats). The insulating component has a mineral wool plate 8 at the side remote from the surface 2.

A bore 9 extends through the inner layer 1, the insulating plates 3 and 4 and the insulating mat 5 and into the insulating mat 6.

A ceramic support sleeve 10 with a large external thread 11 is screwed into the bore 9.

A spacer disc 1 2 is screwed or pushed onto the external thread 11 and engages the surface 2. The support sleeve 10 extends beyond the surface 2 and terminates with a head 14.

The section of the sleeve 10 between the spacer disc 12 and the head 14 constitutes a support member.

At its end remote from the head 14 the support sleeve 10 has an annular shoulder 1 5 in its interior. After screwing in the support sleeve 10, a needle or the like which is not illustrated is introduced into the support sleeve 10 and used to perforate the insulating mat 7 and the mineral wool plate 8 thereby forming a passage 1 6 whose diameter is substantially smaller than the external diameter of the support sleeve 10. A disc nut 1 7 comprising a disc 18 and an internally threaded sleeve 1 9 is inserted into the passage 1 6 in the mineral wool plate 8.

An anchor peg 20 with one end externally threaded and carrying a head 20' at the other end is inserted into the support sleeve 10 and pushed through into the passage 1 6. The anchor peg 20 is screwed into the threaded sleeve 1 9 until its head 20' engages the shoulder 1 5. The support sleeve 10 is thus fastened to the insulating component. This fastening remains secure even if the inner layer 1 or the insulating plates 3 and 4 become so worn that the bore 9 becomes enlarged. If it is feared that this enlargement of the bore 9 may lead to the support sleeve 10 tilting downwardly the insulating plate 3 can be replaced by an insulating plate of a harder material, for example a calcium silicate plate or a small light refractory brick plate.

In practice the insulating component has a plurality of support sleeves 10, as may be seen in Fig. 2. In the furnace lining shown in Fig. 2 there are six insulating components and three support sleeves 10 are provided per insulating component. An electric heating strip 21 is carried by the support members 1 3 which as a consequence of the spacer discs 1 2 are spaced by an appropriate distance from the surface 2 (see Fig. 3).The heating strip 21 is applied in vertical loops and passes over the support members 1 3 and under the projecting ends of sleeves 10' which are the same as the support sleeves 1 0. In order to avoid adjacent sections of the heating strip 21 contacting one another, e.g. by reason of the magnetic fields which develop, suitable spacer studs 22 can be provided between such sections, which studs are screwed into the inner layer 1 and the insulating plates 3 and 4. In the case of the lower sleeves 10' and the spacer studs 22 an anchor peg 20 is unnecessary because these components do not carry the weight of the heating strip 21.

Each insulating component is mounted on two anchor members 23 which are secured to a furnace wall 24. The anchor members 23 have tips 23' which engage in the insulating components. In order to avoid the anchor members 23 bending under the weight of the insulating components which carry the heating strip 21 the angled anchor members 23 are provided with a reinforcing plate 23".

It will be appreciated that various modifications may be made to the embodiment described above. This it is, for instance, possible to omit the discs 1 8 or to provide a common expanded metal strip or mesh or a metal network which extends over the entire breadth of the insulating component and serves as an abutment for the threaded sleeves 1 9. In this embodiment, the threaded sleeve 1 9 need only be provided with small diameter discs 18 in comparison with those described above.

Claims

1. An insulating component for the lining of an electrically heated furnace including a pluraity of layers of insulating material and at least one support sleeve of refractory material which is received in a respective bore which extends through that layer which will form the inner surface of the furnace but extends over only a part of the depth of the component, one end of the or each support sleeve projecting proud of the said layer and carrying a head spaced from the said layer, that portion of the or each support sleeve between the said layer and the associated head constituting a support member for supporting an electrical heating element, the component also including an anchor peg associated with the or each support sleeve of which one end is located with respect to the associated support sleeve and the other end is screw threadedly connected to an opposing member disposed on the side of the component remote from the said layer.

2. A component as claimed in claim 1, including a spacer disc arranged on the or each support sleeve which engages the said layer and is spaced from the associated head.

3. A component as claimed in claim 1 or 2 in which the or each support sleeve comprises ceramic material.

4. A component as claimed in any one of the preceding claims in which the opposing member comprises a threaded sleeve connected to a disc engaging the side of the component remote from the said layer.

5. A component as claimed in any one of claims 1 to 3, in which the opposing member comprises a threaded sleeve connected to an expanded metal mesh or a metal network.

6. A component as claimed in any one of the preceding claims in which the diameter of the anchor peg is smaller than the external diameter of the support sleeve.

7. A component as claimed in any one of the preceding claims in which the said layer is of shell-like construction and has a portion which extends parallel to the remaining layer and a portion which extends over the edges of the remaining layers, the remaining layers comprising a plurality of insulating plates and a plurality of insulating mats and the bore extending through only some of the insulating plates and mats.

8. A component as claimed in any one of the preceding claims in which the or each support sleeve has an external screw thread and is screwed into the associated bore.

9. An insulating component for the lining of an electrically heated furnace substantially as specifically herein described with reference to the accompanying drawings.

10. An electrically heated furnace including a lining comprising a plurality of insulating components as claimed in any one of the preceding claims.

11. A furnace as claimed in claim 10 including one or more heating elements carried by the support members of the insulating components.