- Email: [email protected]
Filter press operation
@ INVENTIONSINFILTRATIONANDSEPARATION Abstracts of British Patents Filter press operation
Oecanter
In GB 2258621 E d w a r d s & J o n e s Ltd d e s c r i b e s a filter press. After f o r m i n g a filter cake in t h e c h a m b e r s of a filter press (by filtering under upstream pressure and then squeezing the cake u s i n g i n f l a t a b l e d i a p h r a g m s ) , t h e cake is f u r t h e r d r i e d by a p p l y i n g s u c t i o n to t h e f i l t r a t e o u t l e t ducts. T h e drying m a y b e e n h a n c e d by h e a t i n g t h e cake, p o s s i b l y by u s i n g h o t w a t e r to inflate d i a p h r a g m s , o r electrical o r fluid h e a t ing in t h e p r e s s p l a t e s , or r e s i d u a l h e a t from a p r e v i o u s w a s h i n g step. S o m e a i r m a y also b e bled into t h e c h a m b e r s through the slurry inlets and sucked t h r o u g h t h e cake.
In GB 2259460 B l a d e E n g i n e e r i n g Ltd d e s c r i b e s a d e c a n t e r for t h e s e p a r a t i o n of l i q u i d s o r solids from a s l u d g e or slurry, s u c h as sewage or p a p e r pulp. A t a n k of r e i n f o r c e d c o n c r e t e h a s a t o n e e n d a s l u d g e / s l u r r y inlet, a n d a t t h e o p p o s i n g e n d a liquid o u t l e t t h r o u g h which substantially clear liquid or w a t e r is to b e r e m o v e d . Two p e r f o r a t e d p l a t e s a r e a r r a n g e d close to t h e outlet, a n d a t a n a n g l e w i t h r e s p e c t to t h e outlet. In t h e p r e f e r r e d version, t h i s a n g l e is a p p r o x i m a t e l y 75 °. A c h a m b e r is f o r m e d by a g a p b e t w e e n t h e two p l a t e s to f o r m a ' t w o - s t a g e ' d e c a n t e r . It is p o s s i b l e to m o v e a t l e a s t t h e first p l a t e by sliding in a v e r t i c a l direction, in o r d e r to d i s t u r b t h e s l u r r y solid phase and cause further secondary decanting.
Ozone filter and method of production In GB 2258622 N i c h l a s C o r p o r a t i o n d e s c r i b e s a n o z o n e filter for d e c o m p o s ing o z o n e in t h e air. It c o m p r i s e s a c a r r i e r f o r m e d by a p a p e r m a d e from i n o r g a n i c fibres h a v i n g a p o r o s i t y of 7 0 - 9 5 % . The c a r r i e r is i m p r e g n a t e d w i t h a s o l u t i o n of fine p o w d e r - l i k e activated manganese dioxide, disp e r s e d in w a t e r a n d h a v i n g a p a r t i c l e size from 0.3 to 50 # m a n d a specific surface a r e a of n o t less t h a n 100 m 2 / g in a n a m o u n t of n o t less t h a n 40 g / m 2, o n a d r y w h i t e b a s e of a c t i v a t e d m a n g a n e s e dioxide. T h e b a s e is allowed to a d h e r e t o t h e carrier, a n d is then dried. The ozone filter thus p r o d u c e d is m o r e active a n d h a s a l o n g e r life w i t h a r e d u c e d p r e s s u r e loss t h a n c o n v e n t i o n a l o z o n e filters.
Multi-well filtration apparatus
Filter assembly
In GB 2 2 5 9 6 5 5 t h e 3M C o m p a n y d e s c r i b e s a multi-well f i l t r a t i o n a p p a r a t u s . It c o m p r i s e s a h o u s i n g a n d a m u l t i - w e l l f i l t r a t i o n p l a t e , w h i c h is i n s e r t e d into t h e h o u s i n g by p u s h i n g the plate downwards past springl o a d e d latches, u n t i l t h e l a t c h e s s n a p b a c k over e d g e s o n t h e plate. The p l a t e is r e l e a s e d by r o t a t i n g t h e r e s p e c t i v e l a t c h e s a b o u t t h e i r pivots, a n d lifting t h e p l a t e clear. A n o t h e r v e r s i o n u s e s only o n e s p r i n g - l o a d e d l a t c h a n d a fixed flange. The latches engage flanges halfway d o w n t h e wells in t h e plate; t h e h o u s i n g is in two pieces. E a c h well c o n t a i n s a filter t h r o u g h w h i c h f i l t r a t e is d r a w n i n t o a n a l i g n e d cell in t h e h o u s i n g by s u c t i o n a p p l i e d to t h e chamber.
In GB 2258828 BTR plc d e s c r i b e s a filter a s s e m b l y for r e m o v i n g p a r t i c u l a t e m a t t e r from gas. It c o m p r i s e s a collect i o n h o p p e r m o u n t e d b e n e a t h filter e l e m e n t s . A fan d r a w s gas t h r o u g h t h e f i l t e r e l e m e n t s , a n d is a r r a n g e d t o d i r e c t a flow of filtered gas to i m p i n g e o n a n e x t e r n a l surface of t h e c o l l e c t i o n hopper. This tends to vibrate the h o p p e r , a n d so p r o m o t e m o v e m e n t of p a r t i c u l a t e m a t t e r d o w n w a r d s over a n i n t e r n a l , i n c l i n e d surface of t h e h o p p e r to a n outlet. T h e fan a n d h o p p e r m a y b e e n c l o s e d by a c o u s t i c walls, w i t h t h e gas (air) e x i t i n g t h r o u g h a grille a n d a d o o r allowing a b i n to b e p l a c e d u n d e r t h e outlet. T h e filter e l e m e n t s a r e of t h e i n w a r d - f l o w type, f r o m w h i c h p a r t i c u l a t e s a r e r e m o v e d by reverse-flow j e t s or by m e c h a n i c a l v i b r a t i o n .
In GB 2259869 Pall C o r p o r a t i o n des c r i b e s a filter u n i t , w h i c h c o m p r i s e s a bowl enclosing a removable filter element and (demountably) attached to a h e a d , h a v i n g a n i n l e t a n d o u t l e t c o n n e c t e d via a b y p a s s valve. A n i n l e t valve c o n n e c t s t h e h e a d i n l e t t o t h e filter e l e m e n t via a space, a n d a n o n r e t u r n valve c o n n e c t s t h e d o w n s t r e a m side of t h e filter e l e m e n t to t h e outlet. W h e n t h e f i l t e r e l e m e n t is t o b e r e p l a c e d , t h e i n l e t valve is closed a n d t h e p a s s valve a u t o m a t i c a l l y o p e n s . T h e i n t e r i o r of t h e bowl is d e p r e s s u r i s e d by o p e n i n g a v e n t valve, a n d d r a i n e d by r e m o v i n g a plug. T h e bowl m a y t h e n b e r e m o v e d f r o m t h e h e a d . A f t e r t h e bowl h a s b e e n r e p l a c e d o n t h e h e a d , it is
Filtration & Separation
November 1993
Filter unit
r e p r e s s u r i s e d by o p e n i n g a n o t h e r valve c o n n e c t i n g t h e s p a c e w i t h t h e outlet, a n d fluid emerges. T h e valve is t h e n closed a n d t h e i n l e t valve is o p e n e d .
A p p a for r separating a t u s oil om an oil/water mixture
In GB 2260133 D o m n i c k H u n t e r Ltd d e s c r i b e s a n a p p a r a t u s for s e p a r a t i n g oil f r o m a n o i l / w a t e r m i x t u r e . I t c o m p r i s e s a n e n t r y p o r t into a gas release region, within a wall. An i m p e r m e a b l e liquid feed t u b e e x t e n d s from t h e i n t e r i o r of t h e gas r e l e a s e region, to o p e n into t h e lower p a r t of a separation chamber which has an o u t l e t only in its u p p e r p a r t . T h e o u t l e t opens into a settlement chamber, and a n oil o u t l e t o p e n s from a n u p p e r region of the settlement chamber a b o v e t h e level of t h e o u t l e t a n d b e l o w t h e level of t h e gas release region. A s o r b e n t b e d is c o n t a i n e d in a f u r t h e r separation chamber. A water outlet l e a d s f r o m a l o w e r r e g i o n of t h e settlement chamber, and water may flow t h r o u g h to t h e s o r b e n t bed. A final water outlet leads from the s o r b e n t b e d a t a level b e l o w t h e oil outlet.
Filter press cloth assembly I n GB 2 2 6 0 9 1 4 S c a p a G r o u p Plc d e s c r i b e s a filter c l o t h a s s e m b l y w h e r e two c l o t h s o n o p p o s i t e s i d e s of a filter p r e s s p l a t e are c o n n e c t e d by a t u b u l a r s e c t i o n e x t e n d i n g t h r o u g h a hole in t h e plate. The t u b u l a r s e c t i o n is m a d e from t h e two cloths, or f r o m s e p a r a t e pieces of t h e r m o p l a s t i c fabric which are s u b s e q u e n t l y a t t a c h e d to t h e cloths. A hole is m a d e in e a c h c l o t h o r fabric, a n d t h e m a t e r i a l a r o u n d t h e hole is h e a t e d a n d d e f o r m e d by a h e a t e d p l u g to f o r m a t u b u l a r p o r t i o n . T h e two p o r t i o n s a r e t e l e s c o p e d t o g e t h e r , a n d s e c u r e d by a d h e s i v e o r by welding. A f a s t - c u r e dispersion may be incorporated a r o u n d t h e r o o t s of t h e t u b u l a r portions, in o r d e r to stiffen t h e s e areas. T h e fabric is a p o r o u s filter m e d i u m , b u t it is r e n d e r e d i m p e r v i o u s by a l a t e x c o a t i n g or by m e a n s of a film w h i c h is m e l t e d o n t o it. T h e t u b u l a r p o r t i o n s m a y b e f o r m e d by v a c u u m or blow m o u l d i n g i n s t e a d of a plug.
[]
NPI THZ, UI~ 631
Oecanter
In GB 2258621 E d w a r d s & J o n e s Ltd d e s c r i b e s a filter press. After f o r m i n g a filter cake in t h e c h a m b e r s of a filter press (by filtering under upstream pressure and then squeezing the cake u s i n g i n f l a t a b l e d i a p h r a g m s ) , t h e cake is f u r t h e r d r i e d by a p p l y i n g s u c t i o n to t h e f i l t r a t e o u t l e t ducts. T h e drying m a y b e e n h a n c e d by h e a t i n g t h e cake, p o s s i b l y by u s i n g h o t w a t e r to inflate d i a p h r a g m s , o r electrical o r fluid h e a t ing in t h e p r e s s p l a t e s , or r e s i d u a l h e a t from a p r e v i o u s w a s h i n g step. S o m e a i r m a y also b e bled into t h e c h a m b e r s through the slurry inlets and sucked t h r o u g h t h e cake.
In GB 2259460 B l a d e E n g i n e e r i n g Ltd d e s c r i b e s a d e c a n t e r for t h e s e p a r a t i o n of l i q u i d s o r solids from a s l u d g e or slurry, s u c h as sewage or p a p e r pulp. A t a n k of r e i n f o r c e d c o n c r e t e h a s a t o n e e n d a s l u d g e / s l u r r y inlet, a n d a t t h e o p p o s i n g e n d a liquid o u t l e t t h r o u g h which substantially clear liquid or w a t e r is to b e r e m o v e d . Two p e r f o r a t e d p l a t e s a r e a r r a n g e d close to t h e outlet, a n d a t a n a n g l e w i t h r e s p e c t to t h e outlet. In t h e p r e f e r r e d version, t h i s a n g l e is a p p r o x i m a t e l y 75 °. A c h a m b e r is f o r m e d by a g a p b e t w e e n t h e two p l a t e s to f o r m a ' t w o - s t a g e ' d e c a n t e r . It is p o s s i b l e to m o v e a t l e a s t t h e first p l a t e by sliding in a v e r t i c a l direction, in o r d e r to d i s t u r b t h e s l u r r y solid phase and cause further secondary decanting.
Ozone filter and method of production In GB 2258622 N i c h l a s C o r p o r a t i o n d e s c r i b e s a n o z o n e filter for d e c o m p o s ing o z o n e in t h e air. It c o m p r i s e s a c a r r i e r f o r m e d by a p a p e r m a d e from i n o r g a n i c fibres h a v i n g a p o r o s i t y of 7 0 - 9 5 % . The c a r r i e r is i m p r e g n a t e d w i t h a s o l u t i o n of fine p o w d e r - l i k e activated manganese dioxide, disp e r s e d in w a t e r a n d h a v i n g a p a r t i c l e size from 0.3 to 50 # m a n d a specific surface a r e a of n o t less t h a n 100 m 2 / g in a n a m o u n t of n o t less t h a n 40 g / m 2, o n a d r y w h i t e b a s e of a c t i v a t e d m a n g a n e s e dioxide. T h e b a s e is allowed to a d h e r e t o t h e carrier, a n d is then dried. The ozone filter thus p r o d u c e d is m o r e active a n d h a s a l o n g e r life w i t h a r e d u c e d p r e s s u r e loss t h a n c o n v e n t i o n a l o z o n e filters.
Multi-well filtration apparatus
Filter assembly
In GB 2 2 5 9 6 5 5 t h e 3M C o m p a n y d e s c r i b e s a multi-well f i l t r a t i o n a p p a r a t u s . It c o m p r i s e s a h o u s i n g a n d a m u l t i - w e l l f i l t r a t i o n p l a t e , w h i c h is i n s e r t e d into t h e h o u s i n g by p u s h i n g the plate downwards past springl o a d e d latches, u n t i l t h e l a t c h e s s n a p b a c k over e d g e s o n t h e plate. The p l a t e is r e l e a s e d by r o t a t i n g t h e r e s p e c t i v e l a t c h e s a b o u t t h e i r pivots, a n d lifting t h e p l a t e clear. A n o t h e r v e r s i o n u s e s only o n e s p r i n g - l o a d e d l a t c h a n d a fixed flange. The latches engage flanges halfway d o w n t h e wells in t h e plate; t h e h o u s i n g is in two pieces. E a c h well c o n t a i n s a filter t h r o u g h w h i c h f i l t r a t e is d r a w n i n t o a n a l i g n e d cell in t h e h o u s i n g by s u c t i o n a p p l i e d to t h e chamber.
In GB 2258828 BTR plc d e s c r i b e s a filter a s s e m b l y for r e m o v i n g p a r t i c u l a t e m a t t e r from gas. It c o m p r i s e s a collect i o n h o p p e r m o u n t e d b e n e a t h filter e l e m e n t s . A fan d r a w s gas t h r o u g h t h e f i l t e r e l e m e n t s , a n d is a r r a n g e d t o d i r e c t a flow of filtered gas to i m p i n g e o n a n e x t e r n a l surface of t h e c o l l e c t i o n hopper. This tends to vibrate the h o p p e r , a n d so p r o m o t e m o v e m e n t of p a r t i c u l a t e m a t t e r d o w n w a r d s over a n i n t e r n a l , i n c l i n e d surface of t h e h o p p e r to a n outlet. T h e fan a n d h o p p e r m a y b e e n c l o s e d by a c o u s t i c walls, w i t h t h e gas (air) e x i t i n g t h r o u g h a grille a n d a d o o r allowing a b i n to b e p l a c e d u n d e r t h e outlet. T h e filter e l e m e n t s a r e of t h e i n w a r d - f l o w type, f r o m w h i c h p a r t i c u l a t e s a r e r e m o v e d by reverse-flow j e t s or by m e c h a n i c a l v i b r a t i o n .
In GB 2259869 Pall C o r p o r a t i o n des c r i b e s a filter u n i t , w h i c h c o m p r i s e s a bowl enclosing a removable filter element and (demountably) attached to a h e a d , h a v i n g a n i n l e t a n d o u t l e t c o n n e c t e d via a b y p a s s valve. A n i n l e t valve c o n n e c t s t h e h e a d i n l e t t o t h e filter e l e m e n t via a space, a n d a n o n r e t u r n valve c o n n e c t s t h e d o w n s t r e a m side of t h e filter e l e m e n t to t h e outlet. W h e n t h e f i l t e r e l e m e n t is t o b e r e p l a c e d , t h e i n l e t valve is closed a n d t h e p a s s valve a u t o m a t i c a l l y o p e n s . T h e i n t e r i o r of t h e bowl is d e p r e s s u r i s e d by o p e n i n g a v e n t valve, a n d d r a i n e d by r e m o v i n g a plug. T h e bowl m a y t h e n b e r e m o v e d f r o m t h e h e a d . A f t e r t h e bowl h a s b e e n r e p l a c e d o n t h e h e a d , it is
Filtration & Separation
November 1993
Filter unit
r e p r e s s u r i s e d by o p e n i n g a n o t h e r valve c o n n e c t i n g t h e s p a c e w i t h t h e outlet, a n d fluid emerges. T h e valve is t h e n closed a n d t h e i n l e t valve is o p e n e d .
A p p a for r separating a t u s oil om an oil/water mixture
In GB 2260133 D o m n i c k H u n t e r Ltd d e s c r i b e s a n a p p a r a t u s for s e p a r a t i n g oil f r o m a n o i l / w a t e r m i x t u r e . I t c o m p r i s e s a n e n t r y p o r t into a gas release region, within a wall. An i m p e r m e a b l e liquid feed t u b e e x t e n d s from t h e i n t e r i o r of t h e gas r e l e a s e region, to o p e n into t h e lower p a r t of a separation chamber which has an o u t l e t only in its u p p e r p a r t . T h e o u t l e t opens into a settlement chamber, and a n oil o u t l e t o p e n s from a n u p p e r region of the settlement chamber a b o v e t h e level of t h e o u t l e t a n d b e l o w t h e level of t h e gas release region. A s o r b e n t b e d is c o n t a i n e d in a f u r t h e r separation chamber. A water outlet l e a d s f r o m a l o w e r r e g i o n of t h e settlement chamber, and water may flow t h r o u g h to t h e s o r b e n t bed. A final water outlet leads from the s o r b e n t b e d a t a level b e l o w t h e oil outlet.
Filter press cloth assembly I n GB 2 2 6 0 9 1 4 S c a p a G r o u p Plc d e s c r i b e s a filter c l o t h a s s e m b l y w h e r e two c l o t h s o n o p p o s i t e s i d e s of a filter p r e s s p l a t e are c o n n e c t e d by a t u b u l a r s e c t i o n e x t e n d i n g t h r o u g h a hole in t h e plate. The t u b u l a r s e c t i o n is m a d e from t h e two cloths, or f r o m s e p a r a t e pieces of t h e r m o p l a s t i c fabric which are s u b s e q u e n t l y a t t a c h e d to t h e cloths. A hole is m a d e in e a c h c l o t h o r fabric, a n d t h e m a t e r i a l a r o u n d t h e hole is h e a t e d a n d d e f o r m e d by a h e a t e d p l u g to f o r m a t u b u l a r p o r t i o n . T h e two p o r t i o n s a r e t e l e s c o p e d t o g e t h e r , a n d s e c u r e d by a d h e s i v e o r by welding. A f a s t - c u r e dispersion may be incorporated a r o u n d t h e r o o t s of t h e t u b u l a r portions, in o r d e r to stiffen t h e s e areas. T h e fabric is a p o r o u s filter m e d i u m , b u t it is r e n d e r e d i m p e r v i o u s by a l a t e x c o a t i n g or by m e a n s of a film w h i c h is m e l t e d o n t o it. T h e t u b u l a r p o r t i o n s m a y b e f o r m e d by v a c u u m or blow m o u l d i n g i n s t e a d of a plug.
[]
NPI THZ, UI~ 631