Scale removal with liquid membrane

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Patents to t h e b a s i c i n v e n t i o n i s to f l u s h the surface with hot water.

w h e r e Ar is: a n u n s u b s t i t u t e d or i n e r t l y s u b s t i t u t e d p h e n y l e n e or n a p h t h y l e n e , or:

Patent number: F R 2 6 5 3 6 7 9 Date: 3 r d M a y 1991 Inventor: D. W a t r e l o t

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Ma .etic liquid membrane

where the link L between the two r i n g s c a n b e a s i n g l e b o n d , a C I - C I s a l k y l c h a i n , a CI-C8 h a l o g e n a t e d a l k y l c h a i n , or -O-, -CO-, -S-, -SO-, -SO2- or -SS-, or: a d i v a l e n t b i s p h e n y l f l u o r e n y l or spiro indanyl radical.

A s u p p o r t e d Liquid m e m b r a n e contains finely divided magnetic p a r t i c l e s ( s u c h a s Fe304) c o a t e d with an inert material such as s i l i c a or a p o l y m e r i c m a t e r i a l . T h e membrane's properties can be altered by imposing a magnetic field o n it.

Patent number: J P 3 1 4 6 1 1 9 Date: 2 1 J u n e 1 9 9 1 Inventor: F. T a k a h a s h i Applicant: TDK C o r p o r a t i o n

Benzotrifluoride aryl ether polymer The a c t i v e l a y e r i n t h i s m e m b r a n e , w h i c h Is p a r t i c u l a r l y s u i t e d to separation and recycle of hydrogen in h y d r o c r a c k i n g , h y f l r o t r e a t i n g or c a t a l y t i c c r a c k i n g p r o c e s s e s , is a polymer with a backbone s t r u c t u r e of b e n z o t r i f l u o r i d e a n d aromatic residues connected by aryl ether linkages. The general f o r m u l a is:

CF,

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X a n d Y a r e h y d r o g e n , a CI-C4 g r o u p (with or w i t h o u t h a l o g e n s u b s t i t u t i o n ) or a h a l o g e n a t o m . P r e f e r r e d h a l o g e n i s fluorine. P r e f e r r e d v a l u e for n is 10-250, but should be such that the polymer has adequate physical strength. These polymers are prepared by condensing a benzotrlfluoride c o m p o u n d c o n t a i n i n g two dlsplaceable groups, such as f l u o r i n e or c h l o r i n e , w i t h a b i s p h e n o l i c c o m p o u n d in a n aprotlc solvent such as N - m e t h y l - 2 - p y r r o l i d i n o n e or N,N-dimethylacetamide in the p r e s e n c e of p o t a s s i u m c a r b o n a t e . The reaction takes place at 4 0 - 2 0 0 ° C u n d e r n i t r o g e n . The r e a c t i o n m i x t u r e is n e u t r a l i s e d a n d t h e p o l y m e r is p r e c i p i t a t e d b y c o n t a c t i n g t h e filtrate w i t h a n alcohol-water mixture.

Patent number: US 5 0 3 0 2 5 2 Date: 9 J u l y 1991 Inventors: E.S. S a n d e r s , T.L. P a r k e r Applicant: D o w C h e m i c a l Co.

Scale

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Many waters have high enough levels of a l k a l i n e e a r t h m e t a l i o n s to c a u s e scaling; t h o s e t h a t

c o n t a i n h i g h levels of b a r i u m present a particular problem, because conventional chemical descaling does not dissolve barium sulphate. These problems are e n c o u n t e r e d m o s t l y in s u b s u r f a c e water, p a r t i c u l a r l y t h a t a s s o c i a t e d w i t h oflflelds. T h e u s e of s e a w a t e r a s a n i n j e c U o n fluid to m a i n t a i n t h e p r e s s u r e in a n oflfleld c a u s e s p r o b l e m s , b e c a u s e of i t s s u l p h a t e content. Severely scaled e q u i p m e n t m a y h a v e to b e r e m o v e d m e c h a n i c a l l y or t h e e q u i p m e n t m a y e v e n h a v e to b e d i s c a r d e d . I n e x t r e m e c a s e s , a well m a y h a v e to b e a b a n d o n e d . Mobil Off h a s d e v e l o p e d a liquid membrane technique which removes scale more quickly than conventional treatments. An e m u l s i o n is u s e d (see F i g u r e ) in which the external and internal aqueous phases comprise an alkaline solution, preferably potassium hydroxide and with a p H of 12, w h i c h is m i x e d w i t h a c o m p l e x i n g a g e n t s u c h a s EDTA or d i e t h y l e n e t r i a m i n e p e n t a a c e tic a c i d (DTPA) a n d a s c a l e r e m o v a l c a t a l y s t , In t h i s c a s e o x a l a t e ion a t 0. I - 0 . 6 M. T h e l i q u i d m e m b r a n e p h a s e is a w a t e r - l m m i s c i b l e hydrocarbon, chlorinated h y d r o c a r b o n or e t h e r c o n t a i n i n g a complexing agent such as a tertiary alkyl amine. The m e c h a n i s m for s c a l e r e m o v a l is t h a t of a c h a i n of complexing agents: the tertiary a m i n e i n t h e h y d r o c a r b o n p h a s e is a s t r o n g e r c o m p l e x i n g a g e n t for the scale-forming ions than the o x a l a t e I o n s in t h e e x t e r n a l

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M e m b r a n e Technology

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Features a q u e o u s p h a s e : the EDTA or DTPA in the i n t e r n a l a q u e o u s p h a s e is stronger than the tertiary amine. So ions a r e initially d i s s o l v e d in the p o t a s s i u m h y d r o x l d e / E D T A / oxalate solution, a r e e x c h a n g e d into the h y d r o c a r b o n / t e r t i a r y a m i n e layer, a n d a r e finally c h e l a t e d b y t h e EDTA in the internal phase. Thls c a n n o t go on for ever" the i n t e r n a l p h a s e ' s c a p a c i t y is finite, so the e m u l s i o n m a y be b r o k e n a n d r e f o r m e d periodically. Thls is not u s u a l l y a n o p t i o n w h e n d e s c a l i n g well casing, where the e m u l s i o n is u s u a l l y c i r c u l a t e d for some h o u r s , s o m e t i m e s also b e i n g p u m p e d into t h e a d j a c e n t r o c k formation.

interfering c o m p o n e n t relative to a c o m p o n e n t of interest. It could also be u s e d in l a r g e - s c a l e chemical s y n t h e s i s , where s t e a d y - s t a t e diffusion of two components across a membrane d o e s not s e p a r a t e t h e m a d e q u a t e l y .

Patent number: EP 4 3 8 7 2 2 Date: 31 J u l y 1991 Inventors: P.F. D u p u i s , R.A. Bredeweg

AppllcanL. Dow C h e m i c a l Co.

Patent number: US 5 0 3 2 2 8 0 Date: 16 J u l y 1991 Inventors: J.M. Paul, R.L. Morris Applicant: Mobil Off Corp.

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M u l t i c o m p o n e n t fluid feeds c a n be separated using non-steady state c o n d i t i o n s s u c h t h a t the component which permeates at the f a s t e r r a t e is r e m o v e d from the p e r m e a t e side of a m e m b r a n e before t h e c o m p o n e n t w h i c h p e r m e a t e s a t a slower r a t e c a n r e a c h s t e a d y - s t a t e conditions. This is a c h i e v e d b y i n t e r m i t t e n t l y i n t e r r u p t i n g the feed to the m e m b r a n e , u s i n g the device s h o w n in Fig. 1. The p i s t o n is a c t u a t e d d o w n w a r d fron tlme to time, so t h a t it r e s t s on t h e m e m b r a n e which h a s a p o r o u s s u p p o r t u n d e r n e a t h it to p r e v e n t r u p t u r e or u n d u e s t r e t c h i n g . W i t h a p p r o p r i a t e valving, a p e r m e a t e s t r e m e n r i c h e d in the d e s i r e d c o m p o n e n t is collected. Fig. 2 s h o w s the degree of separation between components A a n d B w h i c h Is p o s s i b l e w h e n the a t t a i n m e n t of a s t e a d y s t a t e is i n t e r r u p t e d . An e x a m p l e of its u s e would be in m a s s s p e c t r o m e t r y , to m i n i m i s e t h e u p t a k e of a n

Membrane Technology

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