• To c o m p l e t e t h e S t o r y , there is another similar process which does not involve foam, but utilizes similar forces in separation. E m u l s i o n f r a c t i o n a t i o n operates through liquid-liquid interface tension. If an insoluble liquid is emulsified with water containing an interfacially active agent, and the emulsion is then partially broken, the remaining emulsion at the interface will be enriched with the active agent. This one has not been widely studied, as far as we know. It could remove
detergents from water solution, but cost would be even higher than for foam fractionation. As we see it, it could find use as part of existing or modified solvent extraction processes. Perhaps one ion could be m a d e surface-active selectively; then both an extraction separation and an emulsion fractionation could be carried out in one process. {For more long range trends turn to page 17 A)
on technical trends in this issue of I / E C / • You can find the answer to some of those vexing problems in d e s i g n a n d s c a l e - u p off e q u i p m e n t u s e d In s t i r r e d t a n k s for liquid extraction beginning on page 597. And you will also find an excellent rundown on the effect of operating variables here. Of course, m i x e r s t h e m s e l v e s p l a y a n i m p o r t a n t part in the effectiveness of separation. Several types are discussed along with the various equations for calculating power required. T o top it off, there are some 56 references you will want to have at your elbow for further study. Don't miss this one. • C r y s t a l l i z e r d e s i g n a n d o p e r a t i o n is to a great extent based on experience and know-how. But there are many factors involved in the many theories on crystallization that should be explored before attempting to design equipment (page 607). As many theories as there are, so also are there as many interpretations into good, practical design. But there are excellent guides for you in the article beginning on page 612. Good d e s i g n , b a s e d on sound theory, can lead to u s e f u l a p p l i c a t i o n · T h e third of our equipment selection group considers the problem of applying design information to actual equipment, and of operating the equipment once it is installed (page 623). • Controlled cycling can i m p r o v e v a r i o u s proce s s e s · This new approach to process control and improvement assumes that the time for each part of the cycle in a cyclic process or the amount of material moved in each part of the cycle can be controlled by automatic equipment. T w o e x a m p l e s a r e g i v e n : one on sieve and screen plate distillation equipment and one on packed-plate columns (page 629). • T h e present trend in nuclear reactor design is toward high temperatures, recirculating fluids, and high purity water. Ion e x c h a n g e r s a n d i o n e x c h a n g e r e s i n s play an important part in getting high purity water. T h e group of three articles beginning on page 635 looks at specific exchangers, continuous countercurrent solidliquid contactors, and quality control work on coolants.
• Liquid phase air o x i d a t i o n off isobutane in the absence of any solvent other than the oxidation products is the latest in converting gaseous and liquid hydrocarbons. At low conversion and with rigorous exclusion of metal ions is it possible to prepare tertbutyl hydroperoxide. At high conversion, a mixture of alcohol and peroxide is obtained. Y i e l d s a r e h i g h a n d t h e s y s t e m i s n o t c o r r o s i v e (page 655). • Mathematical derivations of expressions for the effectiveness factor of a catalyst particle often neglect the influence of heat generation on the reaction rate. Now the n o n l i n e a r d i f f e r e n t i a l e q u a t i o n s expressing the conservation of mass and energy for reactions in nonisothermal particle have been s o l v e d o n a n a n a l o g computer· Calculations are for first and second order irreversible reactions taking place in spherical particles. Solutions were also obtained for the case of a first order reaction taking place in a flat plate (page 663). • This month's A n n u a l R e v i e w s will get you abreast of the latest developments in E v a p o r a t i o n as a Unit Operation. P y r o l y s i s o f Coal a n d S h a l e points out the trends which will lead to better products from these materials. T h e r m a l a n d C a t a l y t i c D e c o m p o s i t i o n o f H y d r o c a r b o n s covers the developments in this widely used unit process (page 669). • Our Special Feature gives you m a n a g e m e n t p h i l o s o p h y in supervision and decision o n e q u i p m e n t s e l e c t i o n a n d b u y i n g · Crystallization equipment is the example used, but the principles expressed are quite applicable to problems faced by management in selecting any type of equipment (page 36 A). • Miss the S t a t i s t i c a l D e s i g n column? We miss our author too. Bill Connor has been under the weather for a spell and was not u p to doing his usually fine j o b on Statistics. We wish him a speedy recovery as we feel his readers do also. VOL. 53, N O . 8 ·
AUGUST 1961
15 A
