Heat transfer between dispersed liquid metals and gases in packed beds
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MACKEY
AND
N. A. WARNER
The r a t e s of heat t r a n s f e r o c c u r r i n g d u r i n g the c o u n t e r - c u r r e n t contacting of d i s p e r s e d liquid m e t a l s and g a s e s in t o w e r s packed with ring and s p h e r i c a l p a c k i n g s a r e e x a m i n e d . U s i n g m e r c u r y and a i r a s the heat exchange fluids, heat t r a n s f e r s t u d i e s at r o o m t e m p e r a t u r e a r e d e s c r i b e d and the heat t r a n s f e r m e c h a n i s m s e x a m i n e d . Heat t r a n s f e r data a r e a l s o p r e s e n t e d for the contacting of m o l t e n lead with p r e h e a t e d n i t r o g e n in a pilot plant s c a l e a p p a r a t u s . U t i l i z i n g the m e r c u r y i r r i g a t e d t o w e r a s a r o o m t e m p e r a t u r e analogue of the high t e m p e r a t u r e a p p a r a t u s , the m e c h a n i s m s o p e r a t i n g at high t e m p e r a t u r e (400 ~ to 600~ a r e e x a m i n e d . Two b a s i c heat t r a n s f e r m e c h a n i s m s o p e r a t e below about 400~ the d i r e c t m e c h a n i s m , which r e f e r s to c o n v e c t i v e heat t r a n s f e r a c r o s s the g a s / l i q u i d m e t a l i n t e r f a c e , and the i n d i r e c t m e c h a n i s m , a complex p r o c e s s involving conduction and c o n v e c tion in a s e q u e n c e such a s liquid m e t a l - s o l i d p a c k i n g - g a s p h a s e . Above about 400~ a n o t h e r m e c h a n i s m , r a d i a t i o n heat t r a n s f e r between the liquid m e t a l and its e n v i r o n m e n t , is thought to b e c o m e s i g n i f i c a n t , but e x p e r i m e n t a l e r r o r s m a s k e d its detection in the p r e s e n t study.
A d e t a i l e d knowledge of m e t a l l u r g i c a l s m e l t i n g and r e f i n i n g o p e r a t i o n s d e m a n d s an a p p r e c i a t i o n of the n a t u r e and m a g n i t u d e of the heat t r a n s f e r p r o c e s s i n volved. Complete u n d e r s t a n d i n g of the heat t r a n s f e r m e c h a n i s m s within the r e a c t o r s in which t h e s e o p e r a t i o n s a r e conducted would lead to logical d e s i g n and conditions of o p e r a t i o n to e n s u r e a high efficiency of heat exchange. Also, heat t r a n s f e r r a t e s in high t e m p e r a t u r e m e t a l l u r g i c a l p r o c e s s e s , e.g., iron b l a s t f u r n a c e , I m p e r i a l Smelting F u r n a c e , and other new p r o c e s s d e v e l o p m e n t s , have r e l e v a n c e to the c h a r a c t e r i s t i c s of the m a s s t r a n s f e r f u n c t i o n s , so that heat t r a n s f e r data for t h e s e s y s t e m s would be d e s i r a b l e f r o m t h i s point of view a s well a s that c o n c e r n e d p u r e l y with the exchange of t h e r m a l e n e r g y . T h i s p a p e r d e s c r i b e s an i n v e s t i g a t i o n into the o p e r ation of a d i s p e r s e d liquid m e t a l - g a s , packed bed heat e x c h a n g e r . The liquid m e t a l is b r o u g h t into the d i s p e r s e d s t a t
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