Computer model for magnetic fields in electrolytic cells including the effect of steel parts
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The a x e s X - Y - Z follow each o t h e r in c o u n t e r c l o c k w i s e direction. Lengths a r e given in m e t e r s , c u r r e n t s in k i l o a m p s , and m a g n e t i c f i e l d in g a u s s . Model E l e m e n t s and T h e i r G r a d i n g The m a g n e t i c f i e l d s a r e c r e a t e d by two p r i n c i p a l l y different element types: 1. C u r r e n t - c a r r y i n g c o n d u c t o r s . 2. Steel p a r t s e l e m e n t s . It is not s a t i s f a c t o r y to l i m i t the m o d e l to e l e m e n t s only f o r the pot under c a l c u l a t i o n , - - c u r r e n t c o n d u c t o r e l e m e n t s on the n e i g h b o r pots and the whole s u r r o u n d ing potline a r e of high i m p o r t a n c e and cannot be n e g l e c t e d . In o r d e r to k e e p the m o d e l s i z e and c a l c u l a tion w o r k within r e a s o n a b l e l i m i t s it is n e c e s s a r y howe v e r to m a k e a s t r o n g g r a d i n g of d e t a i l s in the e l e m e n t r e p r e s e n t a t i o n , d e p e n d i n g on the d i s t a n c e to the point under c a l c u l a t i o n . The g r a d i n g is done a s follows with r e f e r e n c e to Fig. 2. Steel p a r t s e l e m e n t s a r e included only for the pot under calculation, because their field contribution dec r e a s e s with the s q u a r e of the d i s t a n c e . Input is given for a d e t a i l e d m o d e l of c u r r e n t c a r r y ing c o n d u c t o r s on the pot under c a l c u l a t i o n , with s p e c i a l c a r e f o r d e t a i l s f o r the c o n d u c t o r s c l o s e to the m e t a l pad. An e x t r a s e t of input v a l u e s is given for the r e p r e s e n t a t i o n of a s i m p l i f i e d m o d e l v e r s i o n of the c u r r e n t s y s t e m of a pot, the m a i n b u s b a r s b e i n g r e p r e s e n t e d
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R e f e r e n c e Axes and Units A l l the e l e m e n t s which m a k e up the m o d e l a r e r e f e r e n c e d to a 3 - d i m e n s i o n a l a x i s s y s t e m with its o r i g i n l o c a t e d in the c e n t e r of the c e l l , on top of the c a r b o n b o t t o m a s shown in F i g . 1. The X - a x i s is a l w a y s c h o s e n in the s a m e d i r e c t i o n a s the m a i n potline c u r r e n t . THORLEIF SELE is associated with Ardal og Sunndal Verk, Oslo 3, Norway. Manuscript submitted September 10, 1973. METALLURGICAL TRANSACTIONS
~;,/-/////~,/)~ ---V Fig. 1--Section of 150 kA cell. VOLUME 5, OCTOBER 1974-2145
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Fig. 2--Pot line geometry.
as for the m a i n model, but with all d e t a i l s s u b s t i t u t e d b y a few s i m p l e c o n d u c t o r s . The p r o g r a m m a n i p u l a t e s with axis d i s p l a c e m e n t on this s i m p l i f i e d model to let it r e p r e s e n t the s u r r o u n d i n g n e i g h b o r i n g pots. As shown in Fig. 2 t h e r e will be 5 n e i g h b o r i n g pots for a cell in the o u t e r row, or 8 for a cell in the i n n e r row. The influence of c u r r e
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