GB1571789A

GB1571789A - Furnace cooling element

Info

Publication number: GB1571789A
Application number: GB5427176A
Authority: GB
Original assignee: James Brown and Sons Ltd
Current assignee: James Brown and Sons Ltd
Priority date: 1976-12-30
Filing date: 1976-12-30
Publication date: 1980-07-16

Description

(54) FURNACE COOLING ELEMENT (71) We, JAMES BROWN & SONS LIMITED (formerly Chestnut Bridge Limited), of Cleveland Brass & Copper Works, Commercial Street, Middlesbrough, Cleveland, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to cooling elements for use in furnaces and is particularly concerned with plate or bosh coolers, or with stave coolers for use in blast furnaces.

According to the invention there is provided a furnace cooling element and comprising first and second wall members arranged in back-toback orientation, and wherein at least said first ruember is of cast metal construction having at least one tube embedded therein during casting, the tube providing a serpentine passage for a coolant passing through the element.

One advantage of using cast-in tubes is that problems with casting porosity are avoided and pressure tightness in service is thus improved.

Coolant supply and/or removal may often be facilitated by locating conduits between the wall member. In particular, newly-supplied coolant can be directed to a region od particularly high temperature; a multiplicity of tubes can be supplied from separate cooling circuits.

The cast-in tube may be of the plain variety, but is preferably either corrugated or finned (externally and/or internally); corrugations or fins on the external surface of the tube minimise the ill effect of voids and cavities during the casting operation and thus improve thermal contact between the casting and the tube, whilst ridging of the tube bore extends the surface and promotes turbulence in the coolant and thus also promotes heat transfer.

Preferably, copper or a copper alloy is cast around a flexible, corrugated, stainless steel tube.

Said second wall member can be of cast metal construction and include cast-in tubes in a similar fashion to the first.

The invention can particularly provide a plate or bosh cooler, wherein said first and second wall members are provided by two generally flat panels spaced from each other and arranged in substantially parallel back-toback orientation, the panels being joined at their forward ends by a nose portion, said panels being cast and having at least one tube embedded therein during casting and providing a serpentine passage for a fluid passing through said tube.

Preferably, the panels constitute a single casting and may be joined at side and/or end regions, and may also be linked by webs extending through the interior of the cooler. As mentioned already, the provision of a hollow interior region allows the Iprovision od a multi plicity of cooling circuits, and it is thus generally preferred that plate coolers according to the invention have at least one embedded tube per panel, and may incorporate a separate embedded tube in the nose region.

With stave coolers, conventionally of castiron, difficulties are sometimes encountered when the furnace is driven to produce continuously high output. The refractory lining of the furnace can be burned away, and the castiron of the coolers exposed to the violent chemical and physical attack by the furnace contents.

The invention can particularly provide a stave cooler in which the first wall member is of cast copper or copper alloy and the second wall member is of refractory material shaped to conform with and be in contact with the first member when arranged back-to-back therewith, said first member having at least one tube embedded therein during casting, the tube providing a serpentine passage for a coolant passing through the cooler.

Preferably the back of said first member is given a ridged configuration and refractory is cast onto the first member, the corrugations improving the keying of the members together.

The improved thermal contact and the use of copper allows increased heat extraction from the refractory and prolongs its life. Should the refractory still be burnt away, the copper or copper alloy of the first wall member resists attack better than cast iron, and coolings will cease only with- - the breaching of the cast-in tube or tubes.

The invention will now be more particularly described, by way of example only, with refer ence to the accompanying drawings, of which Fig. 1 accompanied the Provisional Specifica- tion (as Fig 3), and wherein:- Fig. 1 is a longitudinal sectionat view d a plate or bosh cooler according to the invention; and Fig. 2 is a similar view of a stave cooler according to the invention.

Fig. 1 illustrates a plate cooler 150, having lower and upper planar wall sections 152 and 154 respectively that are spaced apart in back to-back configuration, the cooler further com -prising a nose region 156 projecting in use inwardly towards the furnace interior.

The upper and lower sections of the cooler together with the nose are cast as a single unit, cores being used to leave a hollow interior 158 across which extend ribs 160 to improve the coolers rigidity.

Three tubes are cast into the cooler to pro vide for the passage of coolant fluid. Tube 162 in the upper section of the cooler is arranged to provide a multiplicity of lateral passes for coolant. Tube 164 in the lower section is similarly arranged. Extra cooling capacity is provided in the nose region by tube 166 which is arranged to allow cooling fluid to make two lateral passes.

The respective tubes 162, 164 and 166 each form part of separate cooling circuits. Three inlet conduits, only one of which, 168, is visible in Fig. 1, lie in the hollow interior of the cooler; cold inlet water is thus fed to the ends of the tubes in rhe upper and lower parts which are nearest the nose, where the temp era- ture is highest, and exits from the cooler hav ing made a multiplicity of cooling passes in flowing through tubes 162, 164 to respective outlet pipes 172. The third inlet conduit feeds the nose tube 166, an exit conduit (not visible) similar to the inlet conduits taking spent cool ant fluid froon rhe nose tube back to the heel region and to an outlet as described above.

The cooler is cast from copper and the tubes comprise thin-walled corrugated stainless steel tubing which is flexible enough to be bent into the desired shape before casting. The tubes are located as close as is practicable to the outer surface of the cooler and are fully embedded in the casting so that the full circumference of each tube has a cooling effect. Stainless steel transition pieces made by an investment cast ing process are used to connect the conduits with the tubes; one of these is indicated at 174. The transition pieces are partially cast into the copper together with the tubes; the conduits are push fits in and welded to the transition pieces, the latter being so shaped and so arranged in the mould that the portions for receiving the conduits are longitudinally aligned with the hollow interior space 158 of the casting.

A series of fittings 170, 180 cast into the heel and facilitates the connection with the coolant supply; in this case in addition to the outlet pipes 172 already referred to there are inlet pipes for the upper, lower and nose circuits respectively plus an outlet for the nose circuit; of these only pipe 182 is visible in the figure. The cooler may be mounted for use in a blast furnace in any of a number of known ways; fittings for this purpose have thus not been shown.

In Fig. 2 a stave cooler is indicated generally at 200, and comprises a cast copper portion 202 and a cast refractory portion 204. A corrugated, thin-gauge stainless steel tube 206 is shaped to provide a serpentine (in this case five-pass) passage through the roughly rectangular cooler and is embedded in portion 202 during casting. In order both to economise on the use of copper and to ensure that the full circumference of each pass of tube 206 is effective in cooling, portion 202 is moulded with a series of transverse ridges 208 corresponding with the passes of tube 206.

Using this "back" face of portion 202 having ridges 208 as one part of the mould, refractory material is then cast directly onto portion 202 so as to form the cooler; the ridged nature of the interface helps provide a key between the copper and the refractory.

Water inlet and outlet pipes are provided at 210 and 212 respectively, screwing into stainless steel adaptor pieces 214 and 216 partially cast into potion 202.

It will be appreciated that coolers constructed according to the invention are able to survive damage more readily than previously used designs incorporating coolant-filled chambers. If the wall od such a chamber were breached through heat erosion or physical/ chemical attack, then not only is there escape of coolant into the furnace which may upset the process taking place, but the coolant circult affected has to be identified and shut down.

Coolers according to the present invention can undergo considerable degradation but continue to operate as long as the tubes themselves are not breached. With more than one circuit of cast-in tubes it is possible to isolate the coolant supply to a breached tube and continue operating on the remaining cooling circuits until the cooler can be changed without interrupting production.

It will also be appreciated that the described embodiments are in no way limiting. For example, it is possible to arrange that the nose region of the plate cooler shown in Fig. 1 be detachable. It is this region that is most liable to damage by wear and tear, and can be formed separately (with its own tube(s) and conduits) and welded to the panels 152, 154.

It is thus possible to cut out this weld and replace the nose section if necessary.

Similarly the passes of the cooling tubes of the upper and lower sections of the plate cooler may be more widely spaced where they lie away from the nose region, as less cooling is required at the heel end.

A vent can be provided to the hollow interior 158 in order that any tube failure should not lead to a dangerous build-up of fluid of steam pressure.

It is not necessary that conduits be run between the cast outer wall and an opposed wall element; for instance, a corrugated tube can be bent double before both arms are shaped to give a doubled serpentine passage. Inlet and outlet can then be arranged at a heel area without the need for conduits.

The materials used in the construction of cooling elements according to the invention will vary according to application, but it will be noted that the method of construction allows a minimum of cast metal to be used; this may of course represent a considerable financial saving with more expensive metals such as copper.

WHAT WE CLAIM IS: 1. A furnace cooling element and comprising first and second wall members arranged in sb ck-toqback orientation, and wherein at least said first member is of cast metal construction having at least one tube embedded therein during casting, the tube providing a serpentine passage for a coolant passing through the element 2. A cooling element according to claim 1 wherein said cast metal is copper or a copper alloy.

3. A cooling element according to claim 1 or claim 2, wherein said at least one tube is finned or ridged.

4. A cooling element according to claim 3 wherein said tube is of flexible corrugated construcuon.

5. A cooling element according to claim 4 wherein said tube is of stainless steel.

6. A cooling element according to any one of claims 1 to 5 in the form of a plate or bosh cooler, wherein said first and second wall members are provided by two generally flat panels spaced from each other and arranged in substantially parallel back-to-back orientation, the panels being joined at their forward ends by a nose portion, said panels being cast and having at least one tube embedded therein during casting and providing a serpentine passage for a fluid passing through said tube.

7. A cooler according to claim 6 wherein said panels constitute a single casting. 8. A cooler according to claim 5 or claim 6, wherein the nose portion is arranged to act as the hottest part of the cooler in use, and conduit supply means are arranged between the panels whereby to supply fresh coolant fluid directly into or adjacent to said nose portion.

9. A cooler according to any one of claims 5 to 8 wherein the cooler has at least one embedded tube per panel, coolant being supplied to each from separate circuits.

10. A cooler according to any one od claims 5 to 9 wherein there is provided a separately supplied cooling tube embedded in the nose portion of the cooler.

11. A coder according to any one of claims 5 to 10 wherein the tube or tubes provide in each panel a multiplidty of passes for the coolant, said passes being transversely directed and arranged more closely together towards the nose portion of the cooler.

12. A cooling element according to any one of claims 1 to 5 in the form of a stave cooler, wherein the first wall member is of cast copper or copper alloy and the second wall member is of refractory rnaterial shaped to conform with and be in contact with the first member when arranged ,back-toback therewith, said first member having at least one tube embedded therein during casting, the tube providing a serpentine passage for a coolant passing through the cooler.

13. A cooling element according to claim 12, wherein the face of said first wall member contiguous with said second wall member has a ridged configuration.

14. A cooling element according to claim 13 wherein a multplicity of passes for the coolant is provided by said embedded tube or tubes, the ridges of said ridged configuration being arranged to correspond with the locations of said passes, respective tube passes being in coworated at least partially within the raised portions of the first wall member comprising said ridges.

15. A cooling element in the form of a plate or bosh cooler constructed and arranged for use substantially as described herein with reference to and as shown in Fig. 1 of the accorrDpanying drawings.

16. A cooling element in the form of a stave cooler constructed and arranged for use sub stantially as described herein with reference to and as shown in Fig. 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. It is thus possible to cut out this weld and replace the nose section if necessary. Similarly the passes of the cooling tubes of the upper and lower sections of the plate cooler may be more widely spaced where they lie away from the nose region, as less cooling is required at the heel end. A vent can be provided to the hollow interior 158 in order that any tube failure should not lead to a dangerous build-up of fluid of steam pressure. It is not necessary that conduits be run between the cast outer wall and an opposed wall element; for instance, a corrugated tube can be bent double before both arms are shaped to give a doubled serpentine passage. Inlet and outlet can then be arranged at a heel area without the need for conduits. The materials used in the construction of cooling elements according to the invention will vary according to application, but it will be noted that the method of construction allows a minimum of cast metal to be used; this may of course represent a considerable financial saving with more expensive metals such as copper. WHAT WE CLAIM IS:

1. A furnace cooling element and comprising first and second wall members arranged in sb ck-toqback orientation, and wherein at least said first member is of cast metal construction having at least one tube embedded therein during casting, the tube providing a serpentine passage for a coolant passing through the element

2. A cooling element according to claim 1 wherein said cast metal is copper or a copper alloy.

7. A cooler according to claim 6 wherein said panels constitute a single casting.

8. A cooler according to claim 5 or claim 6, wherein the nose portion is arranged to act as the hottest part of the cooler in use, and conduit supply means are arranged between the panels whereby to supply fresh coolant fluid directly into or adjacent to said nose portion.