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DANEWS

HEATING SYSTEMS

n November 2011,Vallourec Tubos do Brasilplaced an order with Danieli

Centro Combustion inconsortium with the Braziliancompany Interfor, to supply,install and commission a pre-heating furnace foraustenitizing (PHF), and asoaking furnace for tempering(SF) for their plant at Barreiro(MG). Moreover, an existinghardening furnace (HF) andtempering furnace (TF) will bemodi�ed, adapting both to thenew operating conditions.The new facilities will deliver anoticeable improvement to theaustenitizing and temperingprocesses and a markedincrease in production for theseamless tube heat-treatmentline.

Pre-heating and soakingfurnaces are of walking-beamtype and include all auxiliaryequipment. These are rated forcapacities up to 63.8 tph; apiece rate of 60 pipes/hour for244.5 mm OD x 13.5 mm WTpipe sizes.

A point of particular interest isthe electrically driven liftingand travelling mechanisminstalled in both furnaces.Also, a set of wheels, leversand tie rods have been �tted tosupport the lifting andtravelling frame.Each wheel group is connectedthrough a tie rod to aneccentric wheel.Both the lifting and travellingmovement are achieved by anelectro-mechanical group

consisting of eccentric wheelsconnected to gear reducersthrough shafts and a drivinggroup (motors and gear boxes.)

The proposed con�guration forthe PHF pro�le andcombustion system will ensuresafe and trouble-free pipeprocessing in all operatingconditions, maximizing energysavings and allowing easyaccess to the main equipmentfor operation and maintenancepurposes.In this design, waste gasrecovered from the existinghardening furnace is blown athigh speed into the furnacedischarging and lateral walls.An ejector fan guaranteescomplete evacuation of thewaste gas which, after passingthrough a new recuperator, isconveyed to a new stack. A setof burners guarantees correctand uniform pipe heating, evenat high production rates when

heat recovered from waste gasis insuf�cient for this task.

To maximize pipe temperaturehomogeneity in the proposedSF furnace, indirect heating bymeans of re-circulating air pre-heated in external chambersinstalled on the furnace roofhas been chosen.The concept of this furnace isto re-circulate a large volumeof air/fumes inside the furnacechamber at uniformtemperatures in order toequalize and maintain pipetemperature for the entiresoaking time. The heatingchambers are located on thefurnace roof and provided withburners and re-circulation fansto heat and deliver theair/fumes mix into the furnacethrough distribution boxes.With the aim of increasing the�ow speed and improving heattransfer, the base of thedistribution boxes are provided

NEW PREHEATING FURNACEFOR HARDENING / SOAKING at Vallourec Belo Horizonte, Brazil

1 Installation progress atsoaking furnace (SF) asof October 15, 2013.

2 Pre-heating furnace(PHF).

3 PHF: Internal view ofpipe discharging areaduring installation.

Technical datafor OCTG pipes processed

Outer diameter 114.3 - 370 mm

Wall thickness 5.0 -38 mm

Length 6.0 - 14.3 m

Pipe temperaturesat furnace exit

PHF furnace 350 - 450 °C

Hardening 850 - 1,050 °C

Tempering 500 - 750 °C

SF furnace 500 - 800 °C

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with nozzles. The samequantity of air/fumes isreturned to the chamberthrough an opening in thefurnace roof.

Several modi�cations had to bemade to the existing hardeningand tempering furnaces toadapt them to the newoperating conditions:> Flame patterns have beenshortened for the heating zoneburners; this was achieved byreplacing the old burner heads(hardening and tempering) withnew ones that have a differentgeometry.> Flame interference betweenheating and soaking zones hasbeen eliminated by replacingthe existing sloped diaphragmwith a new, straight vertical-shaped diaphragm to create amore effective barrier betweenthe two zones.

> The hardening furnacewaste-gas system was modi�edto allow the new PHF to usewaste gases.> The charging and dischargingdoor and relevant frames werereplaced.

The pre-heating and hardeningfurnaces were successfullycommissioned in April 2013;the soaking furnace is in theinstallation phase now.Commissioning of bothfurnaces is expected to becompleted by February 2014.

Such a large project isimportant for Danieli CentroCombustion’s scorecard. WithVallourec as a long-standingand esteemed client of ourcompany, with a number ofturnkey projects alreadycompleted, this new projectdemonstrates best practices incollaboration, ensuring that�nal outcomes are properlyachieved

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