Thursday, 5. April 2018

Performance upgrade and process optimization

Vertical furnace optimized by OTTO JUNKER

GDMB Verlag, METALL Magazin, 3/2018

In close cooperation between the engineering and maintenance department at Aurubis Zutphen and OTTO JUNKER, a concept was developed to replace the existing horizontal pre-heating zone with two additional vertical heating zones.

Aurubis  Netherlands  B.V.  in Zutphen  is one of  four production  sites of  the Aurubis group’s Flat Rolled Products division. In  Zutphen,  330  employees  fabricate  a wide range of rolled products made from copper and copper alloys with a current finished capacity of 50,000 tonnes p.a.

Strip with a  thickness of up  to 3 mm  is annealed at approx.. 800°C in two vertical furnaces. Years ago, to improve performance,  a  radiation-heated  zone was  built into one of  the  furnaces  to pre-heat  the strip fed horizontally through this area. After  leaving  this pre-heating zone,  the strip was then guided over several rollers into the vertical furnace.

In  close  cooperation between  the  engineering and maintenance department at a  concept was developed  to  replace  the existing  horizontal  pre-heating  zone with two additional vertical heating zones. Particularly the deflection rollers used to guide the hot strip into the vertical furnaces were the cause of recurring quality  problems  due  to  scratches,  as well as high maintenance costs.  Despite making  various  improvements,  such as  special  surface  coatings  or  drives, these  problems  could never  be  avoided completely.

In  addition,  Aurubis  wanted  a  strip clamping  feature  to  reliably  retain  the strip  above  the  furnace  and  prevent  it from  falling  back  into  the  accumulator structure in case of strip breakage.

A further  challenge  was  the  extremely tight schedule: from signing the contract up to delivery, only five and a half months were  available  to  design,  produce  and deliver the solution!

To  minimize  production  downtime,  a short time frame of less than three weeks was  planned  for  the  actual  installation and commissioning phases. Within this short space of time, the old furnace had to  be  dismantled  and  the  new  furnace, complete with  new  system  components and new steel platform, installed and put into operation.

OTTO JUNKER supplied two completely new furnace zones designed as high convection zones fitted with the companies nozzle system. The upper section of the furnace was also sealed with a new entry lock  chamber.  Finally,  the  new  strip-guiding devices, such as deflection rollers  and  the  above-mentioned  retaining mechanism, needed to be installed.

Right on time, the first coil was produced on  the agreed production date. As  time progressed,  the various  line parameters were  adjusted,  enabling  production capacities for some alloys to be increased by up to 15 %!

The modification of this furnace is another  excellent example of how major performance improvements can be achieved in existing furnaces when user’s operating  experience  is  closely  intermeshed with OTTO JUNKER know-how.

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Otto Junker is the global technology and system partner for thermal processes of the aluminium, copper, semi-finished products and foundry industry as well as a European supplier of special stainless steel castings. It has some 700 employees at 5 locations who generate worldwide sales of more than EUR 150 million. Sole owner of Otto Junker Group is the Otto Junker Foundation.

  • Klaus Schmitz
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