EP1443119A1

EP1443119A1 - Cooling stave for shaft furnaces

Info

Publication number: EP1443119A1
Application number: EP03250523A
Authority: EP
Inventors: Samuel A. Franklin
Original assignee: VAI Industries UK Ltd
Current assignee: Primetals Asset Management UK Ltd
Priority date: 2003-01-29
Filing date: 2003-01-29
Publication date: 2004-08-04
Also published as: ATA1052004A; AT413033B

Abstract

The invention relates to a cooling stave for shaft furnaces, especially for direct reduction shaft furnaces, blast furnaces and melter gasifiers. The face of the cooling stave which is designated to face the interior of the furnace is provided with an abrasion resistant metallic or polymeric lining.

Description

The invention relates to a cooling plate for shaft furnaces, especially for direct reduction shaft furnaces, blast furnaces and melter gasifiers.
A modern blast furnace for iron making operates with cooling plates inside the furnace shell. These cooling plates may be plate coolers or stave coolers. A stave is a large panel which fits inside and parallel to the furnace shell and incorporates channels through which water is pumped to provide cooling.
Blast furnace cooling staves may be made from copper or cast iron. The front face of the stave may be flat or ribbed. In the case of ribbed staves, a layer of refractory material may be incorporated or added to the front of the stave.
In the case of copper staves, the softness of the metal may result in damage to the stave during filling of the blast furnace prior to the start of operation. To prevent this damage it is normal practice to apply a layer of refractory material to the front face of the copper staves. That layer may be
refractory bricks or shapes
refractory castable
gunned refractory castable
or a combination of these.
If the refractory is pre-installed, there are however a number of disadvantages associated with handling staves having a layer of refractory material applied to their front face. It is difficult and time consuming to handle these staves due to their increased weight and bulkiness. The most serious problem however is, that the refractory layer may be damaged, and the stave can also be damaged. In all cases the refractory is costly and has only a short lifetime.
It is therefore the object of the present invention to provide a stave which does not have the aforementioned problem of a reduced lifetime of a protective refractory layer.
The object of this invention is achieved by a stave, where at least part of that face of the stave which is designated to face the interior of the furnace is provided with an abrasion resistant lining, which is preferably metal-, polymer- and/or wood-based.
With the present invention it is possible to eliminate part or all of the refractory lining from the front face of the stave. Due to the softness of copper and low alloyed copper, the invention is particularly applicable to such cooling staves as copper staves, but may also be applied to cast iron staves.
The inventive abrasion resistant protection to the stave can be easily handled and is of low cost and does not give any risk of damage to the stave and provides protection against mechanical damage during start-up of the furnace.
The front face of the stave is protected from damage during transport or installation or furnace fill by a thin layer of an abrasion resistant lining. Preferably, the abrasion resistant material could be steel sheet, which may be about 3 mm thick. Alternatively, the abrasion resistant material could be a polymer such as neoprene or silicone and may be about 6 mm thick. Other polymers, like polypropylene, polyamide, ABS or melamine are suitable as well, especially when they are filler- and/or fiber-reinforced. Alternatively, expanded metal sheet can be applied, approximately 2-3 mm thick. Alternatively, wood, plywood, fibreboard or a similar wood-based material can be applied. Wood based materials may be fire retarded.
The abrasion resistant lining is applied in suitable size sheets. Depending upon numerous facts, e.g. geometry of the stave surface, material of the lining, etc., the lining may be comprised of a single sheet having smaller size, the same size or a larger size than the surface of the stave facing the interior of the furnace.
Alternatively, the lining may be comprised of individual sheets, each sheet having a smaller size than the surface of the stavefacing the interior of the furnace. Small sheets may overlap or may 'butt up' to each other or may have gaps between them.
According to an embodiment of the present invention the abrasion resistant lining is attached directly to the surface of the cooling stave. This is particularly applicable in cases where the stave is not ribbed and does not receive a refractory layer or where the refractory layer is applied to the stave after it has been mounted inside the furnace.
According to an alternative embodiment of the present invention the abrasion resistant lining is attached to a layer of refractory material which layer is attached to the surface of the stave.
If the stave has a ribbed face, the grooves formed may be filled with refractory material. The refractory may cover the entire face of the stave, as normal. Where the abrasion resistant lining is applied in this case, it will protect the refractory layer during transport, installation and furnace filling.
The abrasion resistant lining may be attached to the stave by any one of a number of methods, which include bolting, screwing, gluing, welding, brazing, soldering and fixings, which may be embedded within an optional intermediate refractory layer.
Depending upon the material of the stave and the lining and depending upon whether an intermediate refractory layer is present, different attachment methods are applicable, e.g. bolting and screwing for any combination of materials or welding, brazing and soldering where a metallic lining is directly attached to the surface of a copper stave.
Gluing is particularly suitable when a polymeric lining is attached to the surface of a copper or cast iron stave.
According to an embodiment of the present invention the lining is arranged at a distance to the surface of the stave at least in a partial area, thereby forming one or more cavities for receiving refractory material between the lining and the surface of the stave.
The abrasion resistant lining may form part of a mould for casting refractory into the grooves or onto the face of the cooling stave. Castable refractory materials are cast into a mould to form the required profile. The abrasion resistant lining may be shaped to give the required refractory profile whilst the refractory material is cast behind the lining.
In order to facilitate casting refractory material behind the lining, the lining is provided with one or more holes and/or nozzles for permitting pumping and/or pouring castable refractory material into the cavities.
The invention also relates to a cooling system for a shaft furnace, the cooling system being comprised of a number of cooling staves as described herein. According to an embodiment of this cooling systen, the staves are arranged essentially parallel to the furnace shell and the staves also are arranged at a distance to the furnace shell and to each other.
The space between the furnace shell and the staves must also be filled with refractory material. This 'backfill' may be installed by pouring or pumping. In either case, the gaps between adjacent cooling staves must be sealed to prevent the backfill material from flowing out before it sets. The abrasion resistant lining may form part of the system for sealing the gaps during 'backfilling' of the void behind the staves.
According to this embodiment of the present invention the abrasion resistant lining extends over the gaps between the cooling staves at least in a partial area.
The invention is illustrated schematically by way of the enclosed drawings.

Fig. 1: side and front view of stave with abrasion resistant lining
Fig. 2: side and front view of lining with overlapping sheets
Fig. 3: side and front view of lining with non-overlapping sheets
Fig. 4: side view of stave with lining and intermediate refractory layer
Fig. 5: details illustrating different attachment methods.

Fig. 1 shows a schematic representation of a stave 1 with an abrasion resistant lining 2 attached to its surface. A number of ducts 7 can be seen for supplying cooling water to channels (not visible) within the body of the stave 1. The lining 2 extends over the entire area of that surface which is directed to the interior of a furnace. The lining 2 is comprised of a number of individual sheets 3.
Fig. 2 shows an arrangement of individual sheets 3, 3' of lining. Staves 1, 1' are arranged adjacent to each other and with gaps 4, 4' between each other. In the region of gap 4' the sheets 3 are arranged such that they overlap sheets 3' (see also left side f Fig. 2). Respective sheets 3 and 3' do not overlap.
Fig. 3 shows a similar arrangement as Fig. 2, except that there is no overlap between sheets 3 and 3'.
Fig. 4 shows a stave 1 with a lining 2 arranged at a distance 5 to the front face of the stave 1. In this embodiment the lining 2 forms a part of the mould for casting refractory material 6 between the lining 2 and the stave 1.
Fig. 5 shows a number of different possibilities how the abrasion resistant lining can be attached to the stave.
Fig. 5a: with bolts 8. This is applicable irrespective of whether a refractory layer 6 is present or not.
Fig. 5b: with steel clips 9 in the grooves of the stave 1. Again, refractory material 6 may or may not be present.
Fig. 5c: with anchors 10 in the refractory material.
Fig. 5d: with screws 11 into the stave, with refractory material being optional.
Fig. 5e: with bolts 8, e.g. when no refractory layer is present.

Claims

Cooling stave for a shaft furnace, especially a blast furnace, characterised in that at least part of that face of the cooling stave which is designated to face the interior of the furnace is provided with an abrasion resistant lining, which is preferably metal-, polymer- and/or wood-based.
Cooling stave according to claim 1, characterised in that the material for the abrasion resistant lining is selected from steel sheet or plate, expanded metal sheet, plywood, fibreboard or wood sheet and neoprene, silicone or other polymeric materials.
Cooling stave according to claim 1 or 2, characterised in that the lining is comprised of a single sheet having smaller size, the same or a larger size than the surface of the stave facing the interior of the furnace.
Cooling stave according to any one of claims 1 or 2, characterised in that the lining is comprised of individual sheets, each sheet having a smaller size than the surface of the stave facing the interior of the furnace.
Cooling stave according to any one of claims 1 to 4, characterised in that the abrasion resistant lining is attached to the surface of the cooling stave.
Cooling stave according to any one of claims 1 to 4, characterised in that the abrasion resistant lining is attached to a layer of refractory material which layer is attached to the surface of the cooling stave.
Cooling stave according to any one of claims 1 to 6, characterised in that the method of attachment of the lining to the stave is selected from bolting, screwing, gluing, welding, brazing, soldering and fixings, which may be embedded within an optional intermediate refractory layer.
Cooling stave according to any one of claims 1 to 7, characterised in that at least in a partial area the lining is arranged at a distance to the surface of the stave, thereby forming one or more cavities for receiving refractory material between the lining and the surface of the stave.
Cooling stave according to claim 8, characterised in that the lining is provided with one or more holes and/or nozzles for permitting pumping and/or pouring castable refractory material into the cavities.
Cooling system for a shaft furnace, the cooling system being comprised of a number of cooling staves according to any one of claims 1 to 9.
Cooling system for a shaft furnace according to claim 10, the staves being arranged essentially parallel to the furnace shell and the staves being arranged at a distance to the furnace shell and to each other, characterised in that at least in a partial area the lining extends over the gaps between the cooling staves.