GB2137326A - Cooling Elements for Furnaces - Google Patents

Abstract

A cooling element for a blast furnace includes a hollow shell (1) which is adapted to protrude into a furnace wall and is open at its end which, in use, lies substantially flush with the furnace wall. A back plate (8) is provided to close off the open end of the shell and is formed with at least one passageway for the flow of coolant into and out of the shell. In a further embodiment the back plate may take the form of an insert resting against internal lips formed in the shell. The shell may be of copper and the back plate manufactured from copper or steel. <IMAGE>

Description

SPECIFICATION Cooling elements for furnaces This invention relates to cooling elements for furnaces which are adapted to be secured to the outer structural wall of a furnace such that the elements protrude into a refractory lining ofthefurnace.

Cooling elements areconventionally usedto pro- vide cooling ofthewalls of refractory lined blast furnaces. Such elements are connected to exterior pipeworkthrough which a coolant medium, eg water, flows.

Over recent years, a number of advances have been made to improve output rates and operating efficiencies of blastfurnaces. One ofthese improvements has been a move to operate the blast furnace at increased internal pressure. To meet this aim, gas tightness at all joints and openings is a prerequisite.

The cooling elements in the bosh and stack of a blast furnace have by necessity, evolved in design to meet the gas-tightness requirements. Before gas-tightness became necessary it was not common practice for coolers to be manufactured with flangefitmentsfor connection directly to the furnace shell. The onset of gas-tightness requirements led initially to the production of cooling elements manufactured from copper, to which copperflanges were integrally cast. These elements were then bolted to the furnace at the flange, with a gasket between the flange and shell.

Such elements were found to suffer from several disadvantages. Firstly, not all foundries possessed the capabilities for manufacture of copper elements with integrally cast-on flanges. Secondly, leaks often occurred atthejunction ofthe flange and coppershell when subjecting the element to hydraulic testing.

Thirdly, although in use gas-tightness improved initially, overa campaign gas leaks increased due to relative movement ofthe cooler, or gasket deterioration.

Welding of the flange to the furnace structure was impracticable because ofthe need to site weld the copperflanges to the steel shells of the furnace.

Consequentlyitwasnecessaryto replacethecopper flange by a steel flange on the cooling element at source, i.e. the manufacturer's works. Alternative designs proposed included that of simply replacing the copperflange by a steel flange and that of welding a steel band around the back end of the cooling element to enable a steel flange, designed to fit over the band at right angles to it, to be welded to both the cooler and furnace structure as a site weld, being a steel to steel weld.

Whereas these developments have assisted manufacture of castings, several disadvantages remain.

In recent years there has been a move towards refurbishing and reusing copper cooling elements. At the end of a blastfurnace campaign, elements are removed from the stack and bosh area. Refurbishment of these elements then proceeds along some or all of the following lines. The element is externally cleaned (typically by shot blasting) and then straightened in a press. Inlet pipes and core plugs are removed from the back of the element, and the inside then cleaned (typically by steam cleaning). The cooler is subsequently visually inspected and then, after replacement ofthe core plugs, hydraulically or pneumatically tested for signs of leaks. Ultrasonics and/or radiographic examination may be conducted as thought necessary.

Disadvantages of these previous designs of cooling elements include unsatisfactory access to the interior of cooling element for cleaning purposes. Added to this isthetimetakenforcore plug removal and replacement, together with handling time.

An objectofthe present invention isto alleviate or overcome these disadvantages.

According to the present invention in one aspect, there is provided a cooling elementfor a furnace through which, in use, cooling medium is circulated, comprising a hollowshell adaptedto protrudeintoa furnace wall and open at its end which in use lies substantially flush with the furnace wall, and a back plate adapted to close off the open end of the shell and formed with at least one passagewayforthe flow of coolant to and from the shell interior.

According to the present invention in another aspect, there is provided a blastfurnace including cooling elements as described in the preceding paragraph.

The cooling element is preferably formed from copper. The back plate may be manufactured from copper or steel and may be welded to the internal surface of the copper shell. A lip may be cast onto the internal surface ofthe shell, the lip extending around the shell periphery and being located adjacent the open end ofthe shell. In this arrangement, the back plate protrudes into the open end ofthe shell and seats againstthelip.Aflangemaybeweldedtotheexternal surface of the shell.

In an alternative arrangement, a steel backing plate is welded to a steel band welded to the external periphery ofthe shell.

The invention will now be described byway of example with reference to the accompanying di agrammatic drawings, in which Figures 1 to 5 are longitudinal cross-sections of various cooling elements in accordance with the invention.

The cooling element illustrated in Figure 1 compris esa cast hollow copper shell 1 which, during casting is formed with an inwardly extending lip 2 which extends around the peripheryofthe innerwall surface oftheshell art a location closetothe open end ofthe shell. A partition 3 extends between the longitudinal walls ofthe shell 1 to define internal passagewaysfor the incoming and outgoing coolant (eg. water). Once cast, a copper backing plate 4formed with apertures for coolant entering and leaving the shell 1 is placed with one side in contact with the outwardly facing sides ofthe lip 2 and welded to the copper shell 1 .The weld between the shell and the backing plate is indicated by reference numeral 5.

As shown in Figures 2 and 3, a suitably shaped flange 6 may be welded to the external surface of the cooling element shell at the same time as the backing plate4 is welded to the shell internal surface. In Figure 3the backing plate is shown in position within the open end ofthe shell 1 and including an entry or exit conduit 7forconnection to exterior coolant pipework.

The cooling elements illustrated in Figures 4 and 5 include a steel backing plate 8 including an internally threaded insert 9for connection to exterior coolant pipework of the furnace. Asteel strenthening band 10 is located around and welded at 11 to the external periphery ofthe copper shell 1, the steel backing plate then being welded at 12 to the strenthening band 10.

In the arrangement illustrated in Figure 5, studs 13 and nuts 14 are provided to tighten the backing plate8 onto a gasket 15 located between the adjacent faces of thecoppershell 1 and the backing plate.

In use, the cooling elements are inserted into the refractory lining of a blast furnace along bores lying substantially normal to the furnace structural wall.

Once inserted, the elements are secured in place through welds between the eiementflanges and the furnace wall. The apertures formed in the backing plate are then connected into the coolant pipework system ofthe furnace.

Cooling elements as described above set outto achieve two main objectives, these being to improve the likelihood of producing castings free of defects and leakages and to enable during subsequent refurbishment, increased internal cleanliness to be achieved and handling and process time to be reduced. These objectives are essentially achieved by allowing forthe elimination or removal of that part of the cooling element that conventionally contains the core plugs, at the stage of manufacture of the element shell.

At the manufacturing stage in the foundry, a casting is produced without coolant inlet and outlet apertures in place, and without cored holes. Provision is made howeverforthe lip 2 to form an integral part ofthe casting onto which a copper backplate can be later placed and welded in position.

Atthis stage of manufacture, the benefits and advantages to thefoundryman are severalfold. The pattern equipment is less complex and takes less time to manufacture. Sand core manufacture is simplified.

Internai cleaning ofthe casting at the fettling stage is significantly improved. Additionally, product quality in terms of soundness, orfreedom from defects is enhanced.

To complete the manufacturing process, a backing plate which already incorporates the inlet and outlet positions is located on to the element shell and welded in position. This backing plate is processed separately from the copper shell.

When considering refurbished coolers for more than one blastfurnace campaign, the only part ofthe coolant element that is replaced is the backplate 8. The advantages of such a replacement part include ease and guarantee of standard of internal cleaning, avoidance of core plug removal and replacement, renewal or ofwelds for second campaign, and facility for shortening the cooler if so desired.

It is to be appreciated that modifications to the cooling elements can be made without departing from the essential features of the invention described.

CLAIMS (Filed on 16th January 1984) 1. A cooling elementfor a fu rnacethrough which, in use, cooling medium is circulated, comprising a hollow shell adapted to protrude into a furnace wall and open at its end which in use lies substantiallyflush with the furnace wall, and a back plate adapted to close offthe open end ofthe shell and formed with at least one passagewayforthe flow of coolant to and from the shell interior.

2. A cooling element as claimed in claim 1 wherein the shell is formed from copper and wherein the back plate is manufactured from copper or steel and is welded to the internal surface ofthe shell.

3. A cooling element as claimed in claim 1 or claim 2 wherein the internal surface of the shell is formed with an inwardly protruding lip, the lip extending aroundtheshell periphery and being located adjacent the open end oftheshell.

4. A cooling element as claimed in claim 3 wherein the back plate protrudes into the open end ofthe shell and seats againstthe lip.

5. A cooling elementas claimed in anyone ofthe preceding claims wherein a flange is welded to the external surface ofthe shell.

6. A cooling element as claimed in any one of claims 1 to 4wherein a steel backing plate is welded to a steel band secured to the external periphery ofthe shell.

7. A blastfurnace including a cooling element as claimed in any one ofthe preceding claims.

8. A cooling elementfor a furnace substantially as herein described and as described with reference to Figure 1 or Figure 2 or Figure 3 or Figure 4 or Figure 5 oftheaccompanying drawings.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. cooling element shell at the same time as the backing plate4 is welded to the shell internal surface. In Figure 3the backing plate is shown in position within the open end ofthe shell 1 and including an entry or exit conduit 7forconnection to exterior coolant pipework. The cooling elements illustrated in Figures 4 and 5 include a steel backing plate 8 including an internally threaded insert 9for connection to exterior coolant pipework of the furnace. Asteel strenthening band 10 is located around and welded at 11 to the external periphery ofthe copper shell 1, the steel backing plate then being welded at 12 to the strenthening band 10. In the arrangement illustrated in Figure 5, studs 13 and nuts 14 are provided to tighten the backing plate8 onto a gasket 15 located between the adjacent faces of thecoppershell 1 and the backing plate. In use, the cooling elements are inserted into the refractory lining of a blast furnace along bores lying substantially normal to the furnace structural wall. Once inserted, the elements are secured in place through welds between the eiementflanges and the furnace wall. The apertures formed in the backing plate are then connected into the coolant pipework system ofthe furnace. Cooling elements as described above set outto achieve two main objectives, these being to improve the likelihood of producing castings free of defects and leakages and to enable during subsequent refurbishment, increased internal cleanliness to be achieved and handling and process time to be reduced. These objectives are essentially achieved by allowing forthe elimination or removal of that part of the cooling element that conventionally contains the core plugs, at the stage of manufacture of the element shell. At the manufacturing stage in the foundry, a casting is produced without coolant inlet and outlet apertures in place, and without cored holes. Provision is made howeverforthe lip 2 to form an integral part ofthe casting onto which a copper backplate can be later placed and welded in position. Atthis stage of manufacture, the benefits and advantages to thefoundryman are severalfold. The pattern equipment is less complex and takes less time to manufacture. Sand core manufacture is simplified. Internai cleaning ofthe casting at the fettling stage is significantly improved. Additionally, product quality in terms of soundness, orfreedom from defects is enhanced. To complete the manufacturing process, a backing plate which already incorporates the inlet and outlet positions is located on to the element shell and welded in position. This backing plate is processed separately from the copper shell. When considering refurbished coolers for more than one blastfurnace campaign, the only part ofthe coolant element that is replaced is the backplate 8. The advantages of such a replacement part include ease and guarantee of standard of internal cleaning, avoidance of core plug removal and replacement, renewal or ofwelds for second campaign, and facility for shortening the cooler if so desired. It is to be appreciated that modifications to the cooling elements can be made without departing from the essential features of the invention described. CLAIMS (Filed on 16th January 1984)

1. A cooling elementfor a fu rnacethrough which, in use, cooling medium is circulated, comprising a hollow shell adapted to protrude into a furnace wall and open at its end which in use lies substantiallyflush with the furnace wall, and a back plate adapted to close offthe open end ofthe shell and formed with at least one passagewayforthe flow of coolant to and from the shell interior.

2. A cooling element as claimed in claim 1 wherein the shell is formed from copper and wherein the back plate is manufactured from copper or steel and is welded to the internal surface ofthe shell.

3. A cooling element as claimed in claim 1 or claim 2 wherein the internal surface of the shell is formed with an inwardly protruding lip, the lip extending aroundtheshell periphery and being located adjacent the open end oftheshell.

4. A cooling element as claimed in claim 3 wherein the back plate protrudes into the open end ofthe shell and seats againstthe lip.

5. A cooling elementas claimed in anyone ofthe preceding claims wherein a flange is welded to the external surface ofthe shell.

6. A cooling element as claimed in any one of claims 1 to 4wherein a steel backing plate is welded to a steel band secured to the external periphery ofthe shell.

7. A blastfurnace including a cooling element as claimed in any one ofthe preceding claims.

8. A cooling elementfor a furnace substantially as herein described and as described with reference to Figure 1 or Figure 2 or Figure 3 or Figure 4 or Figure 5 oftheaccompanying drawings.