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Setting new standards in water treatment technology
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S e t t i n g n e w s t a n d a r d s in water treatment technology D u r i n g the c o n s t r u c t i o n o f a r o a d t u n n e l in Bonn, engineers discot~ e r e d u n a c c e p t a b l y high levels o f p o l l u t a n t s in the g r o u n d w a t e r they h a d to p u m p away. Now the g r o u n ~ w a t e r is being p u r i f i e d in a new, purposc~ built w a t e r t r e a t m e n t p l a n t with a c a p a c i t y o f 5 4 0 0 n d / b m a k i n g it p r o b a b l y the largest p l a n t o f its k i n d ever to be c o m m i s s i o n e d in Europe. After j u s t eight weeks o f p l a n n i n g a n d c o n s t r u c t i o n , the p l a n t came into o p e r a t i o n on sch~ dule in D e c e m b e r 1994. When it is w o r k i n g a t f u l l capacity, with all 122 submersible p u m p s switched on a t once, p o w e r c o n s u m p t i o n rises to a staggering 1.2 megawatts. Clearly, this is no o r d i n a r y p l a n t .
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by Dipl.-Ing Thies Ehlers, Grundfos/ I Wahlstedt
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The e a r t h is full of surprises -- as Bonn's civil engineering i n s p e c t o r a t e discovered when the excavations for the c o n s t r u c t i o n of the p l a n n e d Bad Godesberg road t u n n e l revealed u n a c c e p t a bly high c o n c e n t r a t i o n s of h y d r o c a r b o n s in the groundwater. Analysis of s a m p l e s has so far established only t h a t the w a t e r is c o n t a m i n a t e d by chlorohydrocarbons; the source a n d e x t e n t of the c o n t a m i n a t i o n are still u n k n o w n . But one t h i n g is very clear: u n d e r existing e n v i r o n m e n t a l legislation the p o l l u t e d g r o u n d w a t e r m u s t be t r e a t e d before it is discharged at the outfall. F u r t h e r pressure for action has also come from local residents, who have c o m p l a i n e d a b o u t the u n p l e a s a n t smell given off by the c o n t a m i n a t e d water. The discovery of the g r o u n d w a t e r p o l l u t i o n created a n u n e x p e c t e d p r o b l e m for the city's civil e n g i n e e r i n g i n s p e c t o r a t e because the c o m p l e t i o n date for the entire t u n n e l project now h u n g in the balance. Unless a n early solution could be found to the p o l l u t i o n problem, delays were inevitable. Matters were m a d e worse by the late t i m i n g of the discovery in October, i m m e d i a t e l y before the Rhine reaches its peak flow levels in D e c e m b e r or J a n u a r y . So a p a r t from t h e formidable technical a n d financial difficulties, there was also a critical time factor to be considered.
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Figure 1. In order to complete the work of design and installation in just eight weeks, the whole project had to be planned with extreme precision.
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WORLD PUMPS APRIL 1995
Planning and installation completed in just eight weeks
It was time to call in the experts, a n d B o n n ' s city engineers soon came to a n a r r a n g e m e n t with FWS Filter- u n d Wassertechnik, a specialist c o m p a n y with experience in the t r e a t m e n t of air a n d soil p o l l u t i o n a n d the purification of c o n t a m i n a t e d g r o u n d w a t e r s . Since 1993 the c o m p a n y has been a m e m b e r of "RWE Entsor-
© 1995, Elsevier Science Ltd 0262 1762/95/$7.00
S gung", t h e e n v i r o n m e n t a l e n g i n e e r i n g g r o u p a s s o c i a t e d w i t h t h e regional electricity utility. FWS is e s s e n t i a l l y a s u p p l i e r to t h e industry, p r o v i d i n g e q u i p m e n t a n d e x p e r t i s e to c o m p a n i e s who c a r r y o u t t h e a c t u a l c l e a n - u p o p e r a t i o n on site. After an initial briefing, t h e engineers at FWS design p u t t o g e t h e r a c o m p l e t e p r o c e s s engineering p a c k a g e to d e a l w i t h t h e specific p r o b l e m . The c o m p a n y t h e n m a n u f a c t u r e d t h e n e c e s s a r y c o m p o n e n t s to do t h e job. It h a s b e c o m e m o r e a n d m o r e c o m m o n for FWS to t a k e the e q u i p m e n t u s e d b a c k w h e n a j o b is finished, as it generally m a k e s sense for t h e c l e a n - u p firm to hire r a t h e r t h a n p u r c h a s e t h e e q u i p m e n t for t h e r e l a t i v e l y s h o r t p e r i o d of t h e c o n t r a c t . C o n s e q u e n t l y FWS always h a s a s u b s t a n t i a l n u m b e r of c o m p o n e n t s a n d m o d u l e s available, which can quickly be m a d e u p into t a i l o r - m a d e i n s t a l l a t i o n s for specific needs. Every i n s t a l l a t i o n is different in t e r m s of t h e j o b it is r e q u i r e d to do, b u t e s s e n t i a l l y t h e y are all m a d e u p from t h e same basic components. B a s e d a t D u n n i n g e n - S e e d o r f d e e p in t h e S w a b i a n c o u n t r y s i d e , t h e c o m p a n y gave a n u n d e r t a k i n g to t h e a u t h o r i t i e s in Bonn to install a fully f u n c t i o n a l w a t e r t r e a t m e n t p l a n t of s u i t a b l e c a p a c i t y w i t h i n a very s h o r t s p a c e of time. The p l a n t t h a t was finally d e s i g n e d a n d i n s t a l l e d by FWS is p r o b a b l y u n i q u e n o t only in Europe, b u t in t h e entire world. C a p a c i t y is geared to the high water levels that are e n c o u n t e r e d in t h e D e c e m b e r / J a n u a r y period, a n d to t h e p r o j e c t e d p r o g r e s s on t h e t u n n e l c o n s t r u c t i o n project. If necessary, t h e p l a n t is c a p a b l e of t r e a t i n g 5400 m 3 of w a t e r an hour, u s i n g t h e c o m b i n e d lifting c a p a c i t y of 122 s u b m e r s i b l e p u m p s w i t h a t o t a l p o w e r requirem e n t of 1.2 m e g a w a t t s . To give s o m e i d e a of w h a t t h e s e figures mean: t h e p u m p s s u p p l i e d by D a n i s h m a n u f a c t u r e r Grundfos a r e c a p a b l e of filling m o r e t h a n four giant 50 m s w i m m i n g p o o l s e v e r y h o u r . In o r d e r to e n s u r e a n i n t e r r u p t e d p o w e r s u p p l y to t h e p u m p s , t h e designers of t h e p l a n t have i n c o r p o r a t e d a backup g e n e r a t o r system which cuts in a u t o m a t i c a l l y w i t h i n 20 s e c o n d s of a m a i n s p o w e r failure.
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A c t i v a t e d c h a r c o a l to neutralize harmful hydrocarbons
Analysis of t h e c o n t a m i n a t e d w a t e r revealed a c o n c e n t r a t i o n of 1500 m i c r o g r a m s of chlorohyd r o c a r b o n s p e r litre. The w a t e r m u s t be t r e a t e d u n t i l t h e level of p o l l u t i o n falls b e l o w t h e p e r m i t t e d m a x i m u m of 40 m i c r o g r a m s AOX p e r litre w h e n it can safely be d i s c h a r g e d into t h e p u b l i c d r a i n a g e system. A c t i v a t e d c h a r c o a l
h a s p r o v e d highly effective in t h e t r e a t m e n t of w a t e r c o n t a m i n a t e d by h a l o g e n a t e d hydrocarbons, foul-smelling or foul-tasting substances, chlorine and other undesirable constituents. T h a n k s to its large surface a r e a -- an a s t o n i s h ing 1400 m 2 for a single g r a m of a c t i v a t e d c h a r c o a l - it is c a p a b l e of o u t s t a n d i n g cleaning performance. F o r this r e a s o n w a t e r t r e a t m e n t p l a n t s b a s e d on a c t i v a t e d c h a r c o a l technology can function effectively with relatively c o m p a c t filter units, which n o n e t h e l e s s have an e x t r e m e l y long service life. The key to trouble-free a d s o r p tion is to ensure t h a t t h e w a t e r is u n c l o u d e d w h e n it r e a c h e s t h e c h a r c o a l filter. To t h a t end it is p r e t r e a t e d by p a s s i n g it t h r o u g h a m u l t i - l a y e r m e c h a n i c a l filter. The a d v a n t a g e of m e c h a n i c a l p r e f i l t r a t i o n is t h a t t h e full n e u t r a l i z i n g c a p a c i t y of t h e a c t i v a t e d c h a r c o a l can be b r o u g h t to b e a r on t h e t a r g e t e d p o l l u t a n t . At t h e s a m e t i m e t h e flow r e s i s t a n c e of t h e c h a r c o a l filter is signific a n t l y lowered, which m e a n s t h a t t h e p l a n t needs less p u m p i n g c a p a c i t y to o p e r a t e effectively. A d s o r p t i o n t a k e s p l a c e in large steel filter towers, which i n c o r p o r a t e a special d i s p e r s a l or d i s t r i b u t o r m e c h a n i s m to e n s u r e t h a t t h e incoming w a t e r is evenly d i s t r i b u t e d across t h e c h a r c o a l bed. Since this m e a n s t h a t all t h e activated charcoal adsorbs at approximately the s a m e rate, it is p o s s i b l e by r e g u l a r s a m p l i n g to e s t i m a t e the r e m a i n i n g c a p a c i t y of t h e c h a r c o a l with a fair degree of accuracy, so t h a t p r e p a r a tions for t h e e x c h a n g e of t h e filter bed can be m a d e in good time. F r e s h c h a r c o a l arrives by r o a d in special silo trucks, a n d t h e e x c h a n g e o p e r a t i o n obviously needs a certain a m o u n t of forward planning. FWS h a s d e v e l o p e d its own l o g i s t i c a l c h a i n for h a n d l i n g t h e a c t i v a t e d c h a r c o a l d u r i n g t h e e x c h a n g e a n d for reactivating t h e s p e n t filter material. This e n s u r e s t h a t t h e p o l l u t a n t s a d s o r b e d by the c h a r c o a l can be s e p a r a t e d o u t in t h e p r o p e r m a n n e r for f u r t h e r t r e a t m e n t . In effect, the whole p l a n t functions like a g i a n t c h l o r o h y d r o c a r b o n a c c u m u l a t o r , with the activated charcoal acting as the b a t t e r y . The c h a r c o a l a d s o r b s t h e c h e m i c a l p o l l u t a n t s , is s u b s e q u e n t l y r e m o v e d by suction, a n d t h e n r e a c t i v a t e d in a p u r p o s e - b u i l t plant. The p o l l u t a n t s go to a n o t h e r plant, specially licensed a n d a p p r o v e d u n d e r G e r m a n environm e n t a l legislation, w h e r e t h e y are d e s t r o y e d in a s o p h i s t i c a t e d p r o c e s s involving c o n d e n s a t i o n , i n c i n e r a t i o n a n d gas scrubbing. The r e a c t i v a t e d c h a r c o a l is t h e n r e t u r n e d to t h e filter tower, c o m p l e t i n g t h e cycle. The Bonn t r e a t m e n t p l a n t is e q u i p p e d with 28 a c t i v a t e d - c h a r c o a l filter units, h o u s e d in towers o r silos u p to eight m e t r e s in h e i g h t (see Figure 3). The e n g i n e e r in charge can switch in
WORLD PUMPS APRIL 1995
PECIAL FEATURE
Figure 2. SP45 pump
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any s u i t a b l e c o m b i n a t i o n of a d s o r b e r s , d e p e n d ing on t h e v o l u m e of w a t e r to be t r e a t e d a n d t h e level of c o n t a m i n a t i o n recorded. The t e c h n o l o g y is t r i e d a n d tested, a n d very s u i t a b l e for t h e large q u a n t i t i e s of w a t e r involved, t h e l i m i t e d t i m e available a n d t h e type of p o l l u t a n t s e n c o u n t e r e d .
Submersible pumps maximize use of space The p u m p s i n s t a l l e d to lower t h e g r o u n d w a t e r level t r a n s f e r t h e w a t e r first of all to a settling tank, w h e r e t h e space-saving s u b m e r s i b l e p u m p s s u p p l i e d by Grundfos are housed. When t h e c o a r s e r p a r t i c u l a t e m a t t e r h a s s u n k to t h e b o t t o m of t h e tank, t h e g r o u n d w a t e r is d r a w n o u t by t h e s e p u m p s a n d p i p e d to t h e activatedc h a r c o a l filters. To ensure an o p t i m u m r a t e of flow t h r o u g h t h e filter beds, t h e h y d r a u l i c c a p a c i t y of t h e p u m p s h a s to be finely a d j u s t e d by r e g u l a t i n g t h e r o t o r s p e e d ( r p m ) . E a c h filter tower is linked to a n u m b e r of p u m p s , including one reserve p u m p p e r filter, w h i c h c u t s in a u t o m a t i c a l l y if one of the o t h e r u n i t s fails. E a c h b a t t e r y of p u m p s is precisely " t u n e d " to t h e p a r t i c u l a r a d s o r b e r it supplies. One r e a s o n for specifying s u b m e r s i b l e p u m p s was t h e need to g u a r d a g a i n s t frost damage. If the p u m p s were i n s t a l l e d in t h e dry, each w o u l d need to be in c o n t i n u o u s o p e r a t i o n to p r e v e n t it from freezing up. T h a t risk can easily be o b v i a t e d by installing s u b m e r s i b l e p u m p s t h a t o p e r a t e u n d e r w a t e r a t all times. F u r t h e r m o r e , t h e entire p l a n t h a d to be c o n s t r u c t e d on a very confined site, w h e r e t h e r e was scarcely e n o u g h r o o m to i n s t a l l t h e p u m p s in t h e d r y a l o n g s i d e t h e settling tank. So t h e solution a d o p t e d is b o t h logical a n d elegant. The s p a c e o c c u p i e d by t h e
Figure 3. Site plan showing position of filter towers.
WORLD PUMPS APRIL 1995
settling t a n k - which h a d to be p r o v i d e d anyway is p u t to d u a l use, while t h e a d d i t i o n a l e x p e n s e of a p u m p h o u s e h a s been saved.
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Planned and commissioned in a r e c o r d e i g h t w e e k s
The c o n t r a c t o r s h a d j u s t e i g h t w e e k s from r e c e i p t of t h e o r d e r to c o m m i s s i o n i n g of t h e c o m p l e t e d plant. The r e a s o n for this p r e s s u r e was t h a t t h e t r e a t m e n t p l a n t h a d to be r u n n i n g before t h e w o r k of lowering t h e g r o u n d w a t e r level could continue. T h e t r e a t m e n t p l a n t is l i k e l y t o b e in o p e r a t i o n for a n o t h e r 15 m o n t h s , w h e n t h e t u n n e l c o n s t r u c t i o n p r o j e c t is s c h e d u l e d for c o m p l e t i o n -- at which p o i n t it will no longer be n e c e s s a r y to lower t h e g r o u n d w a t e r level. During this p e r i o d it s h o u l d be p o s s i b l e to e s t a b l i s h t h e source of t h e c o n t a m i n a t i o n a n d devise a p e r m a n e n t s o l u t i o n to t h e p r o b l e m -a s s u m i n g it h a s n o t a l r e a d y been d e a l t with by then. F o r such a large p r o j e c t involving so m a n y u n k n o w n s a n d s u c h t i g h t d e a d l i n e s , it is e s s e n t i a l to h a v e a c o m m i t t e d a n d h i g h l y m o t i v a t e d workforce. A t t h e s a m e t i m e it is i m p o r t a n t to have reliable e q u i p m e n t suppliers. The p r o j e c t engineer c a n n o t afford to s p e n d time weighing up t h e m e r i t s a n d s h o r t c o m i n g s of s o m e u n k n o w n p u m p supplier, for e x a m p l e . Having a l r e a d y c o l l a b o r a t e d with Grundfos on a n u m b e r of e a r l i e r projects, FWS knows e x a c t l y who it is d e a l i n g with a n d w h a t to expect. In t h e w o r d s of t h e t e c h n i c a l d i r e c t o r Schmied: "If we have to r e s p o n d quickly in an emergency, it's good to k n o w t h a t in Grundfos we have a s u p p l i e r we can d e p e n d on, who can r e s p o n d with s i m i l a r flexibility a n d deliver t h e goods fast." Grundfos was a s k e d to s u p p l y 122 of t h e i r Type SP45/6 p u m p s , t o g e t h e r with eight s m a l l e r s u b m e r s i b l e p u m p s , all a d a p t e d to t h e requirem e n t s of t h e i n d i v i d u a l adsorbers. The units in question are multi-stage submersible pumps m a n u f a c t u r e d from chrome-nickel steel ( m a t e rial n u m b e r 1.4301). This g r a d e of steel, which is r e s i s t a n t to a very b r o a d s p e c t r u m of corrosive media, is i n v a r i a b l y u s e d for t h e i m p e l l e r s as well. The b e a r i n g s a r e c o n t i n u o u s l y l u b r i c a t e d by t h e fluid m e d i u m , a n d t h e p u m p s a r e c a p a b l e of o p e r a t i n g at sub-zero t e m p e r a t u r e s . The shaft seals with integral grit deflectors a r e d e s i g n e d for a long service life. The p u m p s a r e a l l o c a t e d to t h e 28 a d s o r b e r s a c c o r d i n g to t h e i r t h r o u g h f l o w capacity. Thus t h e s m a l l e s t a d s o r b e r u n i t is s u p p l i e d by two p u m p s , while the larger u n i t s are s u p p l i e d by a
S Built and operated by the same company
battery of seven. In each case the o u t p u t of the battery of p u m p s is m a t c h e d to a specific v o l u m e of a c t i v a t e d c h a r c o a l . To t a k e a c o n c r e t e e x a m p l e : if an a d s o r b e r has a c a p a c i t y of 50 m a, the p u m p s supplying it m u s t be able to deliver 200 m 3 of w a t e r an hour. Wherever c o n d i t i o n s allow, FWS always uses s u b m e r s i b l e p u m p s s u p p l i e d by Grundfos. With their all-stainless steel construction, metal impellers and integral n o n - r e t u r n flaps, they are highly rated by t h e c o m p a n y ' s engineers. One of t h e i r engineers, Dieter Hoffmann, e x p l a i n s the advantages: "When I p u t in an o r d e r for p u m p s it's nice to know t h a t I d o n ' t have to worry a b o u t w h e t h e r the i m p e l l e r is r e s i s t a n t to solvents, or w h e t h e r it is going to react with the w a t e r we are dealing with. Stainless steel behaves essentially like an inert m a t e r i a l w h e n it comes into c o n t a c t with m o s t of the m e d i a we encounter." 90% of the p u m p s used by FW8 are of the s u b m e r s i b l e type, while t h e rest c o n s i s t of stainless-steel CR/CRN units installed in the dry. In the p l a n t engineering business it is also i m p o r t a n t to have a reliable source of spare p a r t s -- a n d to d a t e t h e D a n i s h p u m p m a n u f a c t u r e r has p r o v e d e x t r e m e l y reliable. They carry large stocks of spares, and can supply m o s t parts within 24 hours.
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A n o t h e r u n u s u a l feature of this p r o j e c t is the o n g o i n g i n v o l v e m e n t of FWS, w h o n o t only designed and built the p l a n t but have also, at the client's request, taken on the day-to-day responsibility for r u n n i n g it. The city a u t h o r i t i e s in Bonn have set certain limits on discharges, s t i p u l a t i n g t h a t p o l l u t i o n levels m u s t be guara n t e e d not to e x c e e d 40 m i c r o g r a m s AOX per litre. It is t h e n the job of the p l a n t o p e r a t o r to design and c o n s t r u c t a technical i n s t a l l a t i o n t h a t can deliver t h o s e values, including the i n f r a s t r u c t u r e for t h e supply, r e c o v e r y a n d r e g e n e r a t i o n of the activated charcoal, a d e q u a t e power supplies (plus e m e r g e n c y back-up), and a 24 h o u r o p e r a t i n g guarantee. When the w a t e r c l e a n - u p o p e r a t i o n is c o m p l e t e d , FWS will d i s m a n t l e the entire p l a n t and use the individual c o m p o n e n t s , such as the filter towers and pumps, for future e n v i r o n m e n t a l projects. In effect they recycle t h e i r own plants. So for an agreed price Bonn's city a u t h o r i t i e s are getting a " c o m p l e t e s o l u t i o n " to t h e i r p r o b l e m and for once t h a t r a t h e r overworked e x p r e s s i o n m e a n s exactly w h a t it says. •
Profile Contents include:
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Structure of the Industry Mergers & Acquisitions Technological Trends and Review of Applications Production and Trade Figures Market Statistics: Figures and Forecasts to 1999 Top 2{~ European Manuf~cturers of Electrical Motors and Drives • Comprehensive l)irecto W of European Manufacturers around 300 major companies VITAL INFORMATION FOR . . . manufacturers
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APRIL 1995
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FEATURE
PECIAL FEATURE
S e t t i n g n e w s t a n d a r d s in water treatment technology D u r i n g the c o n s t r u c t i o n o f a r o a d t u n n e l in Bonn, engineers discot~ e r e d u n a c c e p t a b l y high levels o f p o l l u t a n t s in the g r o u n d w a t e r they h a d to p u m p away. Now the g r o u n ~ w a t e r is being p u r i f i e d in a new, purposc~ built w a t e r t r e a t m e n t p l a n t with a c a p a c i t y o f 5 4 0 0 n d / b m a k i n g it p r o b a b l y the largest p l a n t o f its k i n d ever to be c o m m i s s i o n e d in Europe. After j u s t eight weeks o f p l a n n i n g a n d c o n s t r u c t i o n , the p l a n t came into o p e r a t i o n on sch~ dule in D e c e m b e r 1994. When it is w o r k i n g a t f u l l capacity, with all 122 submersible p u m p s switched on a t once, p o w e r c o n s u m p t i o n rises to a staggering 1.2 megawatts. Clearly, this is no o r d i n a r y p l a n t .
I
by Dipl.-Ing Thies Ehlers, Grundfos/ I Wahlstedt
I
The e a r t h is full of surprises -- as Bonn's civil engineering i n s p e c t o r a t e discovered when the excavations for the c o n s t r u c t i o n of the p l a n n e d Bad Godesberg road t u n n e l revealed u n a c c e p t a bly high c o n c e n t r a t i o n s of h y d r o c a r b o n s in the groundwater. Analysis of s a m p l e s has so far established only t h a t the w a t e r is c o n t a m i n a t e d by chlorohydrocarbons; the source a n d e x t e n t of the c o n t a m i n a t i o n are still u n k n o w n . But one t h i n g is very clear: u n d e r existing e n v i r o n m e n t a l legislation the p o l l u t e d g r o u n d w a t e r m u s t be t r e a t e d before it is discharged at the outfall. F u r t h e r pressure for action has also come from local residents, who have c o m p l a i n e d a b o u t the u n p l e a s a n t smell given off by the c o n t a m i n a t e d water. The discovery of the g r o u n d w a t e r p o l l u t i o n created a n u n e x p e c t e d p r o b l e m for the city's civil e n g i n e e r i n g i n s p e c t o r a t e because the c o m p l e t i o n date for the entire t u n n e l project now h u n g in the balance. Unless a n early solution could be found to the p o l l u t i o n problem, delays were inevitable. Matters were m a d e worse by the late t i m i n g of the discovery in October, i m m e d i a t e l y before the Rhine reaches its peak flow levels in D e c e m b e r or J a n u a r y . So a p a r t from t h e formidable technical a n d financial difficulties, there was also a critical time factor to be considered.
B
Figure 1. In order to complete the work of design and installation in just eight weeks, the whole project had to be planned with extreme precision.
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WORLD PUMPS APRIL 1995
Planning and installation completed in just eight weeks
It was time to call in the experts, a n d B o n n ' s city engineers soon came to a n a r r a n g e m e n t with FWS Filter- u n d Wassertechnik, a specialist c o m p a n y with experience in the t r e a t m e n t of air a n d soil p o l l u t i o n a n d the purification of c o n t a m i n a t e d g r o u n d w a t e r s . Since 1993 the c o m p a n y has been a m e m b e r of "RWE Entsor-
© 1995, Elsevier Science Ltd 0262 1762/95/$7.00
S gung", t h e e n v i r o n m e n t a l e n g i n e e r i n g g r o u p a s s o c i a t e d w i t h t h e regional electricity utility. FWS is e s s e n t i a l l y a s u p p l i e r to t h e industry, p r o v i d i n g e q u i p m e n t a n d e x p e r t i s e to c o m p a n i e s who c a r r y o u t t h e a c t u a l c l e a n - u p o p e r a t i o n on site. After an initial briefing, t h e engineers at FWS design p u t t o g e t h e r a c o m p l e t e p r o c e s s engineering p a c k a g e to d e a l w i t h t h e specific p r o b l e m . The c o m p a n y t h e n m a n u f a c t u r e d t h e n e c e s s a r y c o m p o n e n t s to do t h e job. It h a s b e c o m e m o r e a n d m o r e c o m m o n for FWS to t a k e the e q u i p m e n t u s e d b a c k w h e n a j o b is finished, as it generally m a k e s sense for t h e c l e a n - u p firm to hire r a t h e r t h a n p u r c h a s e t h e e q u i p m e n t for t h e r e l a t i v e l y s h o r t p e r i o d of t h e c o n t r a c t . C o n s e q u e n t l y FWS always h a s a s u b s t a n t i a l n u m b e r of c o m p o n e n t s a n d m o d u l e s available, which can quickly be m a d e u p into t a i l o r - m a d e i n s t a l l a t i o n s for specific needs. Every i n s t a l l a t i o n is different in t e r m s of t h e j o b it is r e q u i r e d to do, b u t e s s e n t i a l l y t h e y are all m a d e u p from t h e same basic components. B a s e d a t D u n n i n g e n - S e e d o r f d e e p in t h e S w a b i a n c o u n t r y s i d e , t h e c o m p a n y gave a n u n d e r t a k i n g to t h e a u t h o r i t i e s in Bonn to install a fully f u n c t i o n a l w a t e r t r e a t m e n t p l a n t of s u i t a b l e c a p a c i t y w i t h i n a very s h o r t s p a c e of time. The p l a n t t h a t was finally d e s i g n e d a n d i n s t a l l e d by FWS is p r o b a b l y u n i q u e n o t only in Europe, b u t in t h e entire world. C a p a c i t y is geared to the high water levels that are e n c o u n t e r e d in t h e D e c e m b e r / J a n u a r y period, a n d to t h e p r o j e c t e d p r o g r e s s on t h e t u n n e l c o n s t r u c t i o n project. If necessary, t h e p l a n t is c a p a b l e of t r e a t i n g 5400 m 3 of w a t e r an hour, u s i n g t h e c o m b i n e d lifting c a p a c i t y of 122 s u b m e r s i b l e p u m p s w i t h a t o t a l p o w e r requirem e n t of 1.2 m e g a w a t t s . To give s o m e i d e a of w h a t t h e s e figures mean: t h e p u m p s s u p p l i e d by D a n i s h m a n u f a c t u r e r Grundfos a r e c a p a b l e of filling m o r e t h a n four giant 50 m s w i m m i n g p o o l s e v e r y h o u r . In o r d e r to e n s u r e a n i n t e r r u p t e d p o w e r s u p p l y to t h e p u m p s , t h e designers of t h e p l a n t have i n c o r p o r a t e d a backup g e n e r a t o r system which cuts in a u t o m a t i c a l l y w i t h i n 20 s e c o n d s of a m a i n s p o w e r failure.
m
A c t i v a t e d c h a r c o a l to neutralize harmful hydrocarbons
Analysis of t h e c o n t a m i n a t e d w a t e r revealed a c o n c e n t r a t i o n of 1500 m i c r o g r a m s of chlorohyd r o c a r b o n s p e r litre. The w a t e r m u s t be t r e a t e d u n t i l t h e level of p o l l u t i o n falls b e l o w t h e p e r m i t t e d m a x i m u m of 40 m i c r o g r a m s AOX p e r litre w h e n it can safely be d i s c h a r g e d into t h e p u b l i c d r a i n a g e system. A c t i v a t e d c h a r c o a l
h a s p r o v e d highly effective in t h e t r e a t m e n t of w a t e r c o n t a m i n a t e d by h a l o g e n a t e d hydrocarbons, foul-smelling or foul-tasting substances, chlorine and other undesirable constituents. T h a n k s to its large surface a r e a -- an a s t o n i s h ing 1400 m 2 for a single g r a m of a c t i v a t e d c h a r c o a l - it is c a p a b l e of o u t s t a n d i n g cleaning performance. F o r this r e a s o n w a t e r t r e a t m e n t p l a n t s b a s e d on a c t i v a t e d c h a r c o a l technology can function effectively with relatively c o m p a c t filter units, which n o n e t h e l e s s have an e x t r e m e l y long service life. The key to trouble-free a d s o r p tion is to ensure t h a t t h e w a t e r is u n c l o u d e d w h e n it r e a c h e s t h e c h a r c o a l filter. To t h a t end it is p r e t r e a t e d by p a s s i n g it t h r o u g h a m u l t i - l a y e r m e c h a n i c a l filter. The a d v a n t a g e of m e c h a n i c a l p r e f i l t r a t i o n is t h a t t h e full n e u t r a l i z i n g c a p a c i t y of t h e a c t i v a t e d c h a r c o a l can be b r o u g h t to b e a r on t h e t a r g e t e d p o l l u t a n t . At t h e s a m e t i m e t h e flow r e s i s t a n c e of t h e c h a r c o a l filter is signific a n t l y lowered, which m e a n s t h a t t h e p l a n t needs less p u m p i n g c a p a c i t y to o p e r a t e effectively. A d s o r p t i o n t a k e s p l a c e in large steel filter towers, which i n c o r p o r a t e a special d i s p e r s a l or d i s t r i b u t o r m e c h a n i s m to e n s u r e t h a t t h e incoming w a t e r is evenly d i s t r i b u t e d across t h e c h a r c o a l bed. Since this m e a n s t h a t all t h e activated charcoal adsorbs at approximately the s a m e rate, it is p o s s i b l e by r e g u l a r s a m p l i n g to e s t i m a t e the r e m a i n i n g c a p a c i t y of t h e c h a r c o a l with a fair degree of accuracy, so t h a t p r e p a r a tions for t h e e x c h a n g e of t h e filter bed can be m a d e in good time. F r e s h c h a r c o a l arrives by r o a d in special silo trucks, a n d t h e e x c h a n g e o p e r a t i o n obviously needs a certain a m o u n t of forward planning. FWS h a s d e v e l o p e d its own l o g i s t i c a l c h a i n for h a n d l i n g t h e a c t i v a t e d c h a r c o a l d u r i n g t h e e x c h a n g e a n d for reactivating t h e s p e n t filter material. This e n s u r e s t h a t t h e p o l l u t a n t s a d s o r b e d by the c h a r c o a l can be s e p a r a t e d o u t in t h e p r o p e r m a n n e r for f u r t h e r t r e a t m e n t . In effect, the whole p l a n t functions like a g i a n t c h l o r o h y d r o c a r b o n a c c u m u l a t o r , with the activated charcoal acting as the b a t t e r y . The c h a r c o a l a d s o r b s t h e c h e m i c a l p o l l u t a n t s , is s u b s e q u e n t l y r e m o v e d by suction, a n d t h e n r e a c t i v a t e d in a p u r p o s e - b u i l t plant. The p o l l u t a n t s go to a n o t h e r plant, specially licensed a n d a p p r o v e d u n d e r G e r m a n environm e n t a l legislation, w h e r e t h e y are d e s t r o y e d in a s o p h i s t i c a t e d p r o c e s s involving c o n d e n s a t i o n , i n c i n e r a t i o n a n d gas scrubbing. The r e a c t i v a t e d c h a r c o a l is t h e n r e t u r n e d to t h e filter tower, c o m p l e t i n g t h e cycle. The Bonn t r e a t m e n t p l a n t is e q u i p p e d with 28 a c t i v a t e d - c h a r c o a l filter units, h o u s e d in towers o r silos u p to eight m e t r e s in h e i g h t (see Figure 3). The e n g i n e e r in charge can switch in
WORLD PUMPS APRIL 1995
PECIAL FEATURE
Figure 2. SP45 pump
S
PECIAL FEATURE
any s u i t a b l e c o m b i n a t i o n of a d s o r b e r s , d e p e n d ing on t h e v o l u m e of w a t e r to be t r e a t e d a n d t h e level of c o n t a m i n a t i o n recorded. The t e c h n o l o g y is t r i e d a n d tested, a n d very s u i t a b l e for t h e large q u a n t i t i e s of w a t e r involved, t h e l i m i t e d t i m e available a n d t h e type of p o l l u t a n t s e n c o u n t e r e d .
Submersible pumps maximize use of space The p u m p s i n s t a l l e d to lower t h e g r o u n d w a t e r level t r a n s f e r t h e w a t e r first of all to a settling tank, w h e r e t h e space-saving s u b m e r s i b l e p u m p s s u p p l i e d by Grundfos are housed. When t h e c o a r s e r p a r t i c u l a t e m a t t e r h a s s u n k to t h e b o t t o m of t h e tank, t h e g r o u n d w a t e r is d r a w n o u t by t h e s e p u m p s a n d p i p e d to t h e activatedc h a r c o a l filters. To ensure an o p t i m u m r a t e of flow t h r o u g h t h e filter beds, t h e h y d r a u l i c c a p a c i t y of t h e p u m p s h a s to be finely a d j u s t e d by r e g u l a t i n g t h e r o t o r s p e e d ( r p m ) . E a c h filter tower is linked to a n u m b e r of p u m p s , including one reserve p u m p p e r filter, w h i c h c u t s in a u t o m a t i c a l l y if one of the o t h e r u n i t s fails. E a c h b a t t e r y of p u m p s is precisely " t u n e d " to t h e p a r t i c u l a r a d s o r b e r it supplies. One r e a s o n for specifying s u b m e r s i b l e p u m p s was t h e need to g u a r d a g a i n s t frost damage. If the p u m p s were i n s t a l l e d in t h e dry, each w o u l d need to be in c o n t i n u o u s o p e r a t i o n to p r e v e n t it from freezing up. T h a t risk can easily be o b v i a t e d by installing s u b m e r s i b l e p u m p s t h a t o p e r a t e u n d e r w a t e r a t all times. F u r t h e r m o r e , t h e entire p l a n t h a d to be c o n s t r u c t e d on a very confined site, w h e r e t h e r e was scarcely e n o u g h r o o m to i n s t a l l t h e p u m p s in t h e d r y a l o n g s i d e t h e settling tank. So t h e solution a d o p t e d is b o t h logical a n d elegant. The s p a c e o c c u p i e d by t h e
Figure 3. Site plan showing position of filter towers.
WORLD PUMPS APRIL 1995
settling t a n k - which h a d to be p r o v i d e d anyway is p u t to d u a l use, while t h e a d d i t i o n a l e x p e n s e of a p u m p h o u s e h a s been saved.
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Planned and commissioned in a r e c o r d e i g h t w e e k s
The c o n t r a c t o r s h a d j u s t e i g h t w e e k s from r e c e i p t of t h e o r d e r to c o m m i s s i o n i n g of t h e c o m p l e t e d plant. The r e a s o n for this p r e s s u r e was t h a t t h e t r e a t m e n t p l a n t h a d to be r u n n i n g before t h e w o r k of lowering t h e g r o u n d w a t e r level could continue. T h e t r e a t m e n t p l a n t is l i k e l y t o b e in o p e r a t i o n for a n o t h e r 15 m o n t h s , w h e n t h e t u n n e l c o n s t r u c t i o n p r o j e c t is s c h e d u l e d for c o m p l e t i o n -- at which p o i n t it will no longer be n e c e s s a r y to lower t h e g r o u n d w a t e r level. During this p e r i o d it s h o u l d be p o s s i b l e to e s t a b l i s h t h e source of t h e c o n t a m i n a t i o n a n d devise a p e r m a n e n t s o l u t i o n to t h e p r o b l e m -a s s u m i n g it h a s n o t a l r e a d y been d e a l t with by then. F o r such a large p r o j e c t involving so m a n y u n k n o w n s a n d s u c h t i g h t d e a d l i n e s , it is e s s e n t i a l to h a v e a c o m m i t t e d a n d h i g h l y m o t i v a t e d workforce. A t t h e s a m e t i m e it is i m p o r t a n t to have reliable e q u i p m e n t suppliers. The p r o j e c t engineer c a n n o t afford to s p e n d time weighing up t h e m e r i t s a n d s h o r t c o m i n g s of s o m e u n k n o w n p u m p supplier, for e x a m p l e . Having a l r e a d y c o l l a b o r a t e d with Grundfos on a n u m b e r of e a r l i e r projects, FWS knows e x a c t l y who it is d e a l i n g with a n d w h a t to expect. In t h e w o r d s of t h e t e c h n i c a l d i r e c t o r Schmied: "If we have to r e s p o n d quickly in an emergency, it's good to k n o w t h a t in Grundfos we have a s u p p l i e r we can d e p e n d on, who can r e s p o n d with s i m i l a r flexibility a n d deliver t h e goods fast." Grundfos was a s k e d to s u p p l y 122 of t h e i r Type SP45/6 p u m p s , t o g e t h e r with eight s m a l l e r s u b m e r s i b l e p u m p s , all a d a p t e d to t h e requirem e n t s of t h e i n d i v i d u a l adsorbers. The units in question are multi-stage submersible pumps m a n u f a c t u r e d from chrome-nickel steel ( m a t e rial n u m b e r 1.4301). This g r a d e of steel, which is r e s i s t a n t to a very b r o a d s p e c t r u m of corrosive media, is i n v a r i a b l y u s e d for t h e i m p e l l e r s as well. The b e a r i n g s a r e c o n t i n u o u s l y l u b r i c a t e d by t h e fluid m e d i u m , a n d t h e p u m p s a r e c a p a b l e of o p e r a t i n g at sub-zero t e m p e r a t u r e s . The shaft seals with integral grit deflectors a r e d e s i g n e d for a long service life. The p u m p s a r e a l l o c a t e d to t h e 28 a d s o r b e r s a c c o r d i n g to t h e i r t h r o u g h f l o w capacity. Thus t h e s m a l l e s t a d s o r b e r u n i t is s u p p l i e d by two p u m p s , while the larger u n i t s are s u p p l i e d by a
S Built and operated by the same company
battery of seven. In each case the o u t p u t of the battery of p u m p s is m a t c h e d to a specific v o l u m e of a c t i v a t e d c h a r c o a l . To t a k e a c o n c r e t e e x a m p l e : if an a d s o r b e r has a c a p a c i t y of 50 m a, the p u m p s supplying it m u s t be able to deliver 200 m 3 of w a t e r an hour. Wherever c o n d i t i o n s allow, FWS always uses s u b m e r s i b l e p u m p s s u p p l i e d by Grundfos. With their all-stainless steel construction, metal impellers and integral n o n - r e t u r n flaps, they are highly rated by t h e c o m p a n y ' s engineers. One of t h e i r engineers, Dieter Hoffmann, e x p l a i n s the advantages: "When I p u t in an o r d e r for p u m p s it's nice to know t h a t I d o n ' t have to worry a b o u t w h e t h e r the i m p e l l e r is r e s i s t a n t to solvents, or w h e t h e r it is going to react with the w a t e r we are dealing with. Stainless steel behaves essentially like an inert m a t e r i a l w h e n it comes into c o n t a c t with m o s t of the m e d i a we encounter." 90% of the p u m p s used by FW8 are of the s u b m e r s i b l e type, while t h e rest c o n s i s t of stainless-steel CR/CRN units installed in the dry. In the p l a n t engineering business it is also i m p o r t a n t to have a reliable source of spare p a r t s -- a n d to d a t e t h e D a n i s h p u m p m a n u f a c t u r e r has p r o v e d e x t r e m e l y reliable. They carry large stocks of spares, and can supply m o s t parts within 24 hours.
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CountD, Tel: Nature of Business
A n o t h e r u n u s u a l feature of this p r o j e c t is the o n g o i n g i n v o l v e m e n t of FWS, w h o n o t only designed and built the p l a n t but have also, at the client's request, taken on the day-to-day responsibility for r u n n i n g it. The city a u t h o r i t i e s in Bonn have set certain limits on discharges, s t i p u l a t i n g t h a t p o l l u t i o n levels m u s t be guara n t e e d not to e x c e e d 40 m i c r o g r a m s AOX per litre. It is t h e n the job of the p l a n t o p e r a t o r to design and c o n s t r u c t a technical i n s t a l l a t i o n t h a t can deliver t h o s e values, including the i n f r a s t r u c t u r e for t h e supply, r e c o v e r y a n d r e g e n e r a t i o n of the activated charcoal, a d e q u a t e power supplies (plus e m e r g e n c y back-up), and a 24 h o u r o p e r a t i n g guarantee. When the w a t e r c l e a n - u p o p e r a t i o n is c o m p l e t e d , FWS will d i s m a n t l e the entire p l a n t and use the individual c o m p o n e n t s , such as the filter towers and pumps, for future e n v i r o n m e n t a l projects. In effect they recycle t h e i r own plants. So for an agreed price Bonn's city a u t h o r i t i e s are getting a " c o m p l e t e s o l u t i o n " to t h e i r p r o b l e m and for once t h a t r a t h e r overworked e x p r e s s i o n m e a n s exactly w h a t it says. •
Profile Contents include:
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Structure of the Industry Mergers & Acquisitions Technological Trends and Review of Applications Production and Trade Figures Market Statistics: Figures and Forecasts to 1999 Top 2{~ European Manuf~cturers of Electrical Motors and Drives • Comprehensive l)irecto W of European Manufacturers around 300 major companies VITAL INFORMATION FOR . . . manufacturers
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& drives
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WORLD PUMPS
APRIL 1995
PECIAL
FEATURE