Mass transfer from an oxygen jet to liquid silver
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the r e l a t i v e l y low m e l t i n g point of s i l v e r (961~ b) which a l l o w s the use of a N i m o n i c 75 v e s s e l and c o n v e n tional r e s i s t a n c e wound f u r n a c e s . M o r e o v e r , oxygen is highly soluble in s i l v e r (90 cu c m p e r cu c m of s i l v e r at 1020~ 7) and its c o n c e n t r a t i o n can be m e a s u r e d u si n g s o l i d e l e c t r o l y t e p r o b e s . 8'9 F u r t h e r m o r e , s i l v e r oxides a r e u n s t a b l e at the t e m p e r a t u r e s c o n s i d e r e d and no second p h ase is f o r m e d during blowing. D a t a on the p r o p e r t i e s of s i l v e r including the d i f f u s i v ity of oxygen in s i l v e r a r e a v a i l a b l e in the l i t e r a t u r e . 7'1~
EXPERIMENTAL Apparatus A photograph of the apparatus indicating the principal parts is shown in Fig. I. Pure oxygen from a bank of cylinders was delivered through a Rotameter to a lance, in which it was heated prior to its discharge through a quadrant-shaped converging nozzle (throat diameter 2.53 mm at room temperature*). The sub*The momentumof the .let was calculatedfrom the Rotameterreadingand the cross-secUonalarea of the nozzleallowingfor its expansionat the temperature of operation. The flowthrough the nozzleitselfwas assumedto be adlabaUcand the coefficxentof dischargewas taken as unity. sonic j e t ( m a x i m u m v e l o c i t y 0.8 Mach) i s s u i n g f r o m the n o z z l e was d i r e c t e d v e r t i c a l l y onto the s u r f a c e of m o l t e n s i l v e r contained in a N i m o n i e c r u c i b l e s i t u a t e d in a f u r n a c e . The l a n c e , F i g . 2, f a b r i c a t e d f r o m a N i m o n i c tube (5 c m ID by 55 cm ) contained two e l e c t r i c a l h e a t e r s : a p r i m a r y h e a t e r c o n s i s t i n g of a 1.3 kw C r u s i l i t e e l e m e n t and a 0.6 kw h e a t e r m a d e by winding 26 swg Kanthal w i r e o v e r an a l u m i n a tube. The pow e r input into e a c h h e a t e r was s e p a r a t e l y c o n t r o l l e d by variable transformers. Th e l a n c e , s u p p o r t e d on a r i g i d f r a m e w o r k was r a i s e d or l o w e r e d by a h y d r a u l i c a l l y o p e r a t e d r a m . T h e d i s t a n c e b e t w e e n the n o z z l e tip and the s u r f a c e of the s i l v e r was d e t e r m i n e d using a pointed N i m o n i c r od c o n n e c t e d in s e r i e s with a light bulb and one t e r m i n a l of a 4.5 V b a t t e r y . Th e o t h er t e r m i n a l was co nne c t e d to the N i m o n i c c r u c i b l e . At the s t a r t , the tip of the r o d w as on the s a m e h o r i z o n t a l plane as the n o z z l e e x i t , the rod w a s then l o w e r e d until c o n t a c t w a s m a d e with the s u r f a c e of the s i l v e r which was i n d i c a t e d by VOLUME 3, DECEMBER 1972-3167
Fig. 1--Experimental apparatus: (1) furnace containing silver, (2) preheating furnace, (3) Nimonic lance, (4) lance carriage, (5) hydraulic ram for raising and lowering the lance (partly visible), (6) s t
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