WO1990011377A1

WO1990011377A1 - Consumable furnace components

Info

Publication number: WO1990011377A1
Application number: PCT/GB1990/000460
Authority: WO
Inventors: Timothy Wrigley
Original assignee: Peel Jones Copper Products Limited
Priority date: 1989-03-28
Filing date: 1990-03-28
Publication date: 1990-10-04
Also published as: AU5340090A

Abstract

Consumable, furnace component, such as, a flat plate cooler (11), tuyere (31) or tuyere cooler (21), having at least part of its working surface formed of a refractory material, for instance, a ceramic material, such as nitride-bonded silicon carbide. In the preferred embodiments, the refractory material is formed in strips (14) which are dovetailed into mechanical securement with the adjacent metallic portions (16) of the working surface, are bonded to that surface to form part thereof or are cast integrally therewith during manufacture.

Description

CONSUMABLE FURNACE COMPONENTS

DESCRIPTION

This invention relates to components which are used in furnaces and which are subjected, during such use, to high thermal stresses and attack from surroun¬ ding hot gases and impinging slag and/or molten mat¬ erial. Typical of such components are tuyeres which are used for introducing air blasts into furnaces, tuyere coolers and flat plate coolers used for furnace cooling.

Under the most severe operating conditions, a tuyere is subjected to erosive attack in the form of molten material, such as, molten iron, striking the outer surface of the tuyere in a random manner. The high temperature of the molten material (iron) is such that some melting of the tuyere, which is of a metallic material, usually copper, occurs. This melting of the tuyere can result in tuyere failure due to the molten material from the furnace burning through the body wall of the tuyere, resulting in cooling water from the tuyere being released into the furnace. Under extreme conditions of temperature and erosive attack, the working life of a tuyere can be reduced significantly, necessitating frequent tuyere replacement at no little expense and significant re¬ duction in furnace productivity.

It is an object of the present invention to provide a tuyere, as well as other types of consumable furnace components, which overcome the disadvantages of known components, such as the tuyere discussed above, or at least reduce them substantially. Accordingly, this invention is directed to a consumable, furnace component having at least part of the working surface (as hereinafter defined) thereof formed of a refractory material.

Throughout this specification, the expression "working surface" is used to mean any part of the surface of a consumable furnace component which is exposed to the erosive and metallic attack from the furnace with which the component is associated when in service.

Preferably, the refractory material is in the form of strips, such as, ceramic strips, secured to the otherwise metallic working surface of the consumable furnace component in question.

In a preferred embodiment of component in accor¬ dance with the invention, the refractory material is nitride-bonded silicon carbide, preferably bonded to the normal, metallic working surface, to form part thereof, by means of a suitable high temperature ad¬ hesive. Alternatively, the refractory material in strip form may be dovetailed into mechanical securement with the adjacent metallic portions of the working surface of the component. Otherwise, the refractory material may be cast integrally with metallic material from which the component is normally manufactured.

Advantageously, the refractory material when in strip form can have its outer working surface flush with the remainder of the working surface of the furnace component.

The invention also resides in a furnace fitted with an inventive consumable component as defined above.

Preferred embodiments of consumable furnace com¬ ponent in accordance with the invention will now be described by way of example and with reference to the accompanying drawings in which:

Figure 1 is a plan view of a flat plate cooler;

Figure 2 is a sectional view on the line II- II in Figure 1;

Figure 3 is an end view of the cooler on the line III-III in Figure 1;

Figure ,4 is a sectional view of a tuyere cooler;

Figure 5 is a front end view of the cooler shown in Figure 4;

Figure 6 is a partial front end view of a tuyere;

Figure 7 is a partial sectional view of the tuyere of Figure 6 on the line VII-VII; and

Figure 8 is a partial sectional view of the tuyere of Figures 6 and 7 on the line VIII-VIII.

A first embodiment of consumable furnace component in accordance with the invention in the form of a flat plate cooler for a blast furnace, is shown in Figures 1 to 3 , wherein the cooler is indicated general¬ ly at 11 and comprises a generally flat, hollow body 12 with respective supporting means 13 provided at the rear end thereof.

At the front end or nose of the copper cooler body 12 is a plurality of strip inserts 14 on opposed faces thereof, located within correspondingly-shaped slots in the respective cooler surfaces such that they are flush therewith. Also associated with the working surfaces of the nose of the cooler 11 is another strip insert 15 which is located at the tip thereof.

The strip inserts 14, 15 are made of a refractory material, preferably a ceramic, for instance, nitride- bonded silicon carbide, secured to the copper surfaces of the cooler nose by any suitable means. For example, the inserts 14 may be bonded in the respective slots using a high temperature adhesive. Alternatively, the inserts 14 may be dovetailed into mechanical secure¬ ment with the adjacent copper portions of the cooler 11. The strip insert 15 may be similarly secured to the tip of the nose of the cooler body 12.

Thus, the refractory strip inserts 14, 15 provide a continuously flush surface with the surfaces of the adjacent portions 16 of the copper cooler body 12, with the inserts acting to protect the body 12 from high thermal stresses and attack from surrounding hot gases _nd impinging slag and/or molten material but with the intermediate portions 16 of the copper body 12 being able to perform the required cooling function by heat transfer therethrough from an asso¬ ciated furnace to the cooling medium contained within the cooler 11. These intermediate copper portions 16 also assist in cooling the inserts 14, 15 with which they are in intimate contact, via a bonding adhesive or a mechanical joint, such as, the dovetail arrangement described above, or a combination of both. Such cooling of the inserts 14, 15 is desirable, to prevent their decomposition at elevated operating temperatures.

Referring now to Figures 4 and 5 of the drawings , here is illustrated a second embodiment of consumable furnace component in accordance with the invention in the form of a tuyere cooler which is shown generally at 21 and which is known as a "jumbo" cooler.

In this embodiment, the cooler 21 comprises a generally hollow body 22 with cooling chambers 23 therein, through which is passed a suitable coolant, ideally water.

The working surface at the nose of the cooler 22 is provided with refractory, preferably ceramic, strips 24, as shown clearly in Figure 5, which is a front end view of the nose of the cooler.

The strips 24 are secured to the working surface of the cooler, to form part thereof, by any suitable means , such as any of those described above in relation to the first embodiment of cooler shown in Figures

1 to 3.

Again, the ceramic material used, is preferably nitride-bonded silicon carbide and the strips 24, or indeed the inserts 14, 15 of the cooler 11 shown in Figures 1 to 3, may be cast integrally with the cooler 11, 21 during manufacture thereof. In this manner, the strip inserts 14, 15 of the cooler 11 and the strips 24 of the cooler 21 are, in service, cooled underneath and at the sides due to the compara- tively high thermal conductivity of the adjacent copper body 12, 22, cooling water being pumped or otherwise circulated through the body, with side cooling of the inserts/strips 14, 15, 24.

Turning now to Figures 6 to 8 of the drawings, a third embodiment of inventive consumable furnace component in the form of a tuyere indicated generally at 31, has a body 32 made of copper, with a nose portion 35 which, in service, is subjected to high thermal stresses from the surrounding hot gases and impinging slag and/or molten material from an associated furnace.

Ceramic strips 34 of nitride-bonded silicon carbide are cast integrally with the copper tuyere body 32 leaving strips 36 of copper therebetween. In this manner, the ceramic strips 34 are, in service, cooled underneath and at the sides due to the comparatively high thermal conductivity of the copper, cooling water being pumped through the body 32, with side cooling from the copper strips 36 at either side of the ceramic strips 34. If required, the ceramic strips 34 can be extended over the nose portion 35 of the tuyere 31.

Cooling of the ceramic strips 34 is important, to prevent their decomposition at elevated operating temperatures.

In this third embodiment of inventive tuyere 31, the ceramic strips 34 are cast with the tuyere body 32 during manufacture, preferably employing a dovetail joint between the edges of the ceramic strips 34 and the adjacent copper strips 36, such that the outer surfaces of both the ceramic strips 34 and the copper body strips 36 are flush with each other. ^•

Again, and in the alternative, the ceramic strips 34 may be adhered to the tuyere body 32, set in suitably shaped channels in the body, using a high temperature adhesive.

Any other suitable means of securing the ceramic strips 34 to the tuyere body 32 may be used, although consideration must be given to the heat transfer from the strips 34 through the tuyere body wall 35 to the cooling water,, as discussed above.

As indicated above, the outer, working surfaces of the refractory/ceramic strip inserts 1.4, 15 and strips 24, 32 and the adjacent copper surfaces of respective coolers 11, 21 and tuyere 30 are preferably flush with each other, this being for two main reasons. Firstly, on installation of the components 11, 21, 31, the brittle ceramic or other refractory material inserts/strips are protected from damage due to rough handling, by the surrounding copper of the bodies 12, 22, 32. Secondly, by presenting as smooth a surface as possible of non-wetting properties and minimal nucleation points, adhesion of solidified slag and/or iron is substantially prevented. This "non-stick" property is important when removal of the cooler, tuyere or other furnace component , from the furnace is required, in that any slag and/or iron bonded to the working surfaces makes such removal difficult, and sometimes impossible, due to the locking-in effect of the build-up of slag and/or iron. Such a build¬ up can occur when the inserts/strips of ceramic, or other refractory, material are merely secured to the outer, other working, surfaces of the copper components. Further, non-wetting properties can be enhanced by glazing the outer working surfaces of the refractory inserts/strips.

Moreover, it is to be appreciated that the strip inserts 14, 15 and strips 24, 34 of the respective coolers 11, 21 and tuyere 31 described above are pre¬ formed items which are secured to the inventive con- sumable furnace components, to form at least part of the working surface thereof, rather than the so- called "coatings" of the prior art arrangements which involve the application of protective surface coatings of copper-chromium alloys, a diffused active alumina/ aluminium powder mixture and/or other particulate refractory materials to the working surfaces of furnace components and which do not constitute at least part of the working surface of the associated component as such but really only a coating thereon.

Claims

1. A consumable, furnace component having at least part of the working surface (as hereinbefore defined) thereof formed of a refractory material.

2. A component according to claim 1, wherein the refractory material is in the form of strips.

3. A component according to claim 2, wherein the refractory strips are dovetailed into mechanical secure¬ ment with the adjacent metallic portions of the working surface of the component.

4.. A component according to claim- 2 or 3, wherein the refractory strips are bonded to the metali'ic working surface of the component to form part thereof.

5. A component according to claim 2, wherein the refractory strips are cast integrally with the metallic material from which the component is manufactured.

6. A component according to any preceding claim, wherein the outer working surfaces of the refractory material and adjacent metallic component portions are flush with each other.

7. A component according to any preceding claim, wherein the refractory material is a ceramic material.

8. A component according to claim 7. wherein the refractory material is nitride-bonded silicon carbide.

9. A consumable furnace component according to any preceding claim, which is a flat plate cooler, a tuyere cooler or a tuyere.

10. A consumable furnace component substantially as hereinbefore described with reference to the accom- panying drawings.

11. A furnace when fitted with a consumable component according to any preceding claim.