EAF ELECTRODE CONSUMPTION EQUATION - PRACTICAL APPLICATION

Luis R. Jaccard

The following are our EAF electrode consumption equations:

Ce ( kg / MWh ) = K x ( I² / P ) x ( D² / d² ) ( 1 )

Where:

K: Electrode quality coefficient

I: Current intensity

P: Active power of each arc

D = Original electrode diameter

d = Electrode tip diameter

D² / d² is the conicity of the electrode and represents the lateral oxidation consumption.

We deduced ( see paper in this site ):

D² / d² = { 0,5 + [ 0,25 + ( Kox / K ) x ( D x H / I² ) ]^1/2}² ( 2 )

And:

Ce ( kg / MWh ) = K x ( I² / P ) x { 0,5 + [ 0,25 + ( Kox / K ) x ( D x H / I² ) ]^1/2}² ( 3 )

Where:

Kox/K: Oxidation coefficient / Electrode quality coefficient

H: Oxidation height ( the length of the electrode red portion )

From this equation it is posible to arrive to the following conclusions:

The tip consumption and, generally, the total electrode consumption are proportional to I² / P. As I² / P = P / Va² = I / Va = 1 / Ra we can conclude that usually electrode consumption is inversely proportional to the voltage arc ( Va ) and to the arc resistance.
The oxidation consumption depends on the relation between the oxidation area ( D x H ) and the square of the current.
Usually, a current decrease provokes an electrode consumption reduction, because of the predominant effect of the tip consumption, but in rare cases, when the current density at the electrode is extremely low, the current reduction can increase the electrode consumption. Current density must be as high as posible to obtain the minimum electrode consumption.

PRACTICAL APPLICATION OF THE ELECTRODE CONSUMPTION EQUATION

Presently, we are using the formula with the following coefficients and we have find a good correlation with real cases:

Ce´( kg / MWh ) = 10 x I / Va x [ 0,5 + ( 0,25 + 30 x D x H / I² )^0,5]²

With:

I ( kA ); Va ( V ) ; D ( cm ); H ( m )

Example

D = 60 cm
I = 80 kA
Va = 625 V [ Va = P_1electrode ( kW ) / I ( kA ) ]
H = 2,2 m

Conclusion:

Ce´= 2,62 kg / MWh

APPLY THE FORMULA TO YOUR FURNACES AND CONTACT US !!!