Klapsis 1984 Aquacultural-Engineering

7/28/2019 Klapsis 1984 Aquacultural-Engineering

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Aqua c u l tu ra l Eng ine er ing 3 ( I 984) 103-118

F l o w D i s t r i b u t i o n S t u d i e s in F i s h R e a r i n g T a n k s . P a r t 1- D e s i g n C o n s t r a i n t s

A. Klaps i s and R. Burley

D epa rtm ent o f Chem ical and Process Engineering, Heriot-W att University,Chambers Street , Edinburgh EH1 IHX , UK

A B S T R A C T

T he hy drau l i c be hav iour o f any f i sh - c on ta in ing tank , po nd or si lo i s o fcentra l imp ortan ce to a ll aspects o f in tens ive f i sh rear ing . Th e re t icu la t iono f f lu id and local f lu id ve loc it ie s in par ticu lar sys tems wi l l d irec t ly andindirec t ly a f fec t f i sh phys io logy and me tabol ic ra tes in the in tens iverearing process. I t is also recognised that th e f lu id also has an im po rta ntrole t o p lay in foo d and he a t d i s t r ibu t ion and re mov a l o f w as te so lidmaterial.

This paper there fore rev iews the des ign cons tra in ts p laced upon suchsy s t e ms in the c on te x t o f p rev ious s tud ie s a s an ind ic a tor a s to how tom ake the m ost e f f ic ien t use o f square tank s fo r in tens ive f i sh rear ing ,which is the sub jec t o f Par t 2 o f the pape r {Klapsis and Bur ley , 1984) .

I N T R O D U C T I O NT h e d e s ig n c o n s t r a i n t s o n f i s h r e a ri n g t a n k s , p o n d s , e t c . , a r e se v e ra l.T h e m o s t i m p o r t a n t o f t h e se is c l e ar ly t o e n s u r e th a t t h e e q u i p m e n t i sd e s ig n e d f o r e f f i c i e n t u s e a n d t h e p r o f i t a b i l i t y p e r u n i t v o l u m e ism a x i m i s e d t h r o u g h o u t t h e eq u i p m e n t .

S u c h a m a i n o b j e c t i v e r e q u i r e s a c l e ar u n d e r s t a n d i n g o f h o w f l u id sb e h a v e w h e n e i t h e r i n j e c t e d i n to o r r e m o v e d f r o m l a rg e h o l d in g103


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104 A. Klaps i s , R . Bur leyv o l u m e s a n d w h a t t h e e f f e c t o f t h e h y d r a u l i c c h a r a c t e ri s ti c s w i ll b e o np a r a m e t e r s s u c h a s, f o r e x a m p l e , o x y g e n , flu id v e l o c i t y a n d t e m p e r a t u r ele v el s, d e t r i t u s r e m o v a l a n d f o o d d i s t r i b u t i o n . T h e s e v a r ia b le s ar e a lli n t e r l in k e d t h r o u g h b o t h t h e g e n e r a l f lo w a n d t h e p a r ti c u la r lo c alc o n d i t i o n s t h a t p e r t a i n t o g i ve n fis h re a ri ng m e t h o d s .

I n t h is c o n t e x t i t is in s t r u c t i v e t o l o o k a t p r e v i o u s d e s i g n h i s t o ri e sa n d o b s e rv e t h e p r e v i o u s d e v e l o p m e n t s in r e s p o n s e to d e m a n d f o ri n c r e as i n g p r o d u c t i o n o f i n t e n s i v e l y r e a r e d f is h .

N O T E O N T E R M I N O L O G YI n v ie w o f t h e w i d e r a n ge o f e q u i p m e n t d e v e l o p e d b y t h e i n d u s t ry , i t isu s e f u l t o d e f i n e s o m e o f t h e t e r m s t h a t w i ll b e u s e d l a t e r o n i n th e t e x t .I n t h i s c o n t e x t ' t a n k ' r e f e r s t o p o r t a b l e o r s e m i p o r t a b l e u n i t s u p t o3 . 5 m i n d i a m e t e r , w h i l e ' p o n d ' o r ' p o o l ' re f e r s t o p e r m a n e n t l y i n s ta l le du n i t s u p t o 12 m in d i a m e t e r . T h e p o n d s o r t a n k s c a n h a v e d i f f e r e n tg e o m e t r i e s ; d i a g r a m s o f d i f f e r e n t d e s ig n s a r e p r e s e n t e d i n F ig . 1.

I odPLAN PLAN

I

SECTION ~ RACEWAY SECTONCIRCULAR POND

FOSTER LUCASCROSS- CROSS-SECTION S LO SECTIONFig. l . Diagram of different po nd /tank designs.


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Flow distriburion srudier in fish rearing ranks - I 105HISTORIC DEVELOPMENT OF TANKS/PONDS

Hydraulic characteristics - circular systemsCobb and Titcomb (1930) reported that as early as 1904 Mayhall hadused circular shaped rearing ponds with a central outlet for salmonidhusbandry at the State Hatcheries in Washington State, USA.The pond used by Mayhall was fitted with a water supply from aperforated pipe extending across the middle of the pond, as shown inFig. 2, arranged so as to jet water to try to ensure a clockwise flow of

CENTRE WASTEPIPE

WATERINJECTION

--iiFiO WASTEFig. 2. Diagram of pond used by Mayhall. (See Cobb and Titcomb, 1930.)


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106 A. Klapsgs , R. Bur leywater in the pond with evenly distributed velocity across the radius.The original tanks were 5 ft in diameter and 18 in in depth, but laterdevelopments increased the size to 25, 50 and 100 ft diameter. Theoutlet was a central concrete base into which were set two elbows, oneto take the normal overflow, the other to allow siphoning of f of theaccumulated solids.

This design was later modified by Cobb and Titcomb, replacing theradial pipe with a single tangential pipe at the surface of the water,nearly parallel with the bank at water level.

Surber (1933) also used circular pools with central outlets. A cylin-drical metal leaf screen was placed around the central standpipe whoseupper part lay above the water level whilst its base lay close to thebottom of the pool. Between the base of the central standpipe, whichscrewed into a sleeve in the foundation, and the outer cylinder, metalleaves were arranged to permit the removal of detritus whilst preventingthe passage of fish. This design was found to increase the self-cleaningaction because the water was forced to pass under the screen at arelatively increased velocity thus carrying away the majority of thewaste materials produced from the intensive fish rearing.Burrows and Chenoweth (1955) were the first to report studies inflow pat terns for three model fish holding facilities, namely the circularpond, the Foster gucas and the raceway (Fig. 1).

This was the first detailed study of local velocities for the circularpond as a function of position, albeit for a fixed flowrate/depth con-figuration (Fig. 3).

Burrows and Chenoweth also introduced tracer methods for theanalysis of fluid-based phenomena, such as mixing, by-passing and deadvolumes, which need to be quantified in any real system and scaled-upfrom model studies.

These dye studies showed up areas of poor water interchange causedby the short circuiting (Fig. 4).

The short circuiting effect did, however, encourage movement overthe base of the tank transferring the waste material, settled in the deadareas, to the centre screen.

Studies on the flow patterns of the Foster Lucas and raceway ponds(Fig. 5) showed up similar short circuiting and dead zones of poorwater exchange.

Looking at what are now termed 'Exit Age' distribution responsecurves, we can see some indicat ion of the short circuiting that occurs in


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F l o w d i s t r i b u t i o n s t u d i e s i n f i s h r e ar in g r a n k s - 1 107

~ P r o f o f y p e\~" Qi" ~upwoJ'd s p i r a li d - d e p f h

B) . FLOW PATTERN

3 s - / ~ . , #

A}. PLAN VIEW OFCRCULARPOND CI.NOZZLEVERY LOW VELOCITY

D E A D A R E AHIGH 318" LOPE

I F IM E D I U M V E L O C I T Y

2 ' - 6 "

B " S t d . P I P E O U T L E T

0 ) . S E C T I O N O F C I R C U L A R P O N O

F i g . 3 . D i a g r a m o f c i r c u l a r p o n d .


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1 0 8 A. Klapsis , R. Burley

Fig. 4.SHORTLY AFTE R DYE kS MINUT ES AFT ER DYE

INJECTION INJECTIONDiagram of f low patterns and dead areas c a u s e d b y s h o r t c i r c u i t i n g .

2 9 ' - 6 " 2 7 ' - 0 "I n f t u e n t o r i f i c e s \ -J - ,Sc r eens *ou t l e t p ipe - "

A) GENERAL FLOW PATTERN IN FOSTER LUCA S POND

~ ' I I [ r r l - r ~ . . I E II d y e c r y s t o t s p l a c e d in. . . . . . . . . . . - - . . . , $ ' f f I I t~ystnts ' in"S nr ea ~+ _ \ \

y e c r y s t d s J . , p ' i ,/,/o n b a t, to m - - ' f . ~B) SOME FLOW PATT ERN DE TAILS IN FO STER LUCAS POND

Bend Area70 60 50 t~0 / 30 20 10 0

' - " ~ ' ~ " - . . ' ~ . F ~ - - -~ . , C ~ 2 - 7 - " > b ~ : m I. ~ _ ~ . . . . a : . : : " . ~ _ .. ,~ .. ~ .. . t ~ ~ - - I" - - - - ~ " : - - ~ - ' - ~ -~-S~ ~ = ~ ~ , ~ ~ - - - - - " ; IE) FLOW PATTERN IN A RACEWAY PON0

Fig . 5 . Diagramof Foster Lucas and raceway ponds.

a l l t h e s e p o n d s ( F i g . 6 ) , a n d a s e x p e c t e d t h e r a c e w a y p o n d h a d t h e' b e s t ' o v e ra l l p e r f o r m a n c e . A f u l l e x p l a n a t i o n o f r e sp o n s e c u r ve a n a ly s isis g i ve n i n t h e A p p e n d i x .

L a r m o y e a u x e t a l . ( 1 9 7 3 ) , i n t h e i r s t u d y o f ta n k f l o w b e h a v io u r ,d e s c r i b e d t h e f l o w p a t t e r n s f o r v a r i o u s ( d i a m e t e r / d e p t h ) r a t i o s , g i v e n


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F l o w d i s t r i b u t i o n s t u d i e s in f i s h r e a r in g t a n k s - 1 109

F i g . 6 .

, e , - ~

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~lt~ f,,"/C RCU AR

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0"5 1"0 1"5 2-0 2"5RATIO OF ACTU ALTIHETO THEORETICAL ETENTION THEDiagram showing 'E' curves in al l three model ponds of Burrows and

Chenoweth (1955) .

in F i gs 7 an d 8 . T h e s e s t u d ie s r e v ea l e d t h a t t h e v o l u m e o f t h e w a t e r w a sd i v i d e d i n to f o u r z o n e s, w i t h i n t e r- z o n e v a r i a t i o n b e i ng c r e a t e d b ya n gl in g t h e w a t e r i n l e t j e t s , w h i c h w e r e o f d i f f e r e n t d i a m e t e r s .S i l o sT u r n i n g t o d e e p e r c i r c u l a r t a n k s , i . e . s i l o s , B u s s e t a l . ( 1 9 7 0 ) w e r e t h ef i rs t t o r e p o r t t h e u s e o f v e r t i c a l c y l i n d r i c a l s i lo s f o r i n t e n s i v e fi s hr e a ri n g w i t h a le n g t h - t o - d i a m e t e r r a t i o o f 3 : 1.

L a t e r B u s s ( 1 9 7 5 , 1 9 7 6 ) p a t e n t e d a n d d i sc u s s e d t h e u s e o f s il os i nw h i c h o x y g e n w a s i n t r o d u c e d a t t h e b o t t o m o f th e s i lo t h r o u g h as i m p l e s p a r g e r , a s s h o w n i n F i g . 9 .

T h e f l o w o f w a t e r w i t h i n t h e si lo w a s , a s s h o w n , f r o m t h e b o t t o mt o t h e t o p , s o t h a t f is h w a s t e p r o d u c t s , b o t h s o li d a n d d i s s o l v e d , t e n d e dt o b e c a r r ie d u p w a r d s a n d r e m o v e d f r o m t h e w a t e r a s i t p a s se d f r o mo n e t a n k t o t h e n e x t i n a c a s c a d e s y s te m . M a c V a n e ( 1 9 7 9 ) u s e d a s il ow h e r e t h e w a t e r e n t e r e d t a n g e n t i a l l y a n d d e v e l o p e d a n a s c e n d i n g v o r t e xf l o w .

T h i s s pi ra l a c t i o n , a s si st ed b y t h e sw i m m i n g m o v e m e n t o f th e fi sh ,c a u s e d s o l i d s t o g r a v i t a t e t o w a r d s t h e c e n t r e o f t h e t a n k , fa c i l it a t in gs el f- cl ea n in g o f t h e e q u i p m e n t . T h e b o t t o m o f th e t a n k w a s sh a p e d a sa n i n v e r t e d o b t u s e c o n e w i t h a d r a i n a t t h e c e n t r e . F i n g e r ( 1 9 7 4 ) a l so


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1 1 0 A . K I a p s is , R . B u r l e y

f / ~ ./ A N O .r , \/ \

e ~ ; ~ . - - " T - . I O U T L E T \

~ 1 , ~ I ,_ ; ( ) ~ 1 II \ ~ . ~ e 7 " / I\ \ ~ /

\,,. >NOZZLES / /" I / /

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F i g . 7 .Flow

I I K . . I NL E( ~ . N O Z Z L E S

SECTIONFlow patterns for diameter to depth ratios of 3:1 and less. (After

Larmoyeux e t a l . . 1973.)

pate nted a silo which con tained a perforated water circulating tubewhich ext end ed d ownw ard s along the greater part of its length. A waterheater was used to regulate the water temperature and an air heater wasused to heat the air above the water surface.

Fr uch tni cht (1975) used a silo having a tangentially directed sprinklerfor a water inlet, whilst an evacuation orifice in the base was covered


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Flow distribution studies in fish rearing tanks - 1 111

I NLET

0 NOZZLES

-SECTI ON

Fig. 8. Flow patterns for diameter to depth ratios of 5: 1Larmoyeux et al., 1973.)and 10: 1. (After

by a high removable latticed dome. The water volume was divided byseveral removable floors to form a multistorey tank. Moore (1977) usedconcentrically arranged tanks, of an appropriate volume, to provide anoptimum rate of growth for fish in each stage of their life.


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I 1 2 A . K l a p s i s , R . B u r l e y

I

/W a f e rOuf lei"

I I , 1 W c t e rI n te rq~--- O i f f us e r

Fig. 9 . S i lo due to Bu ss(197 5) .

P r e v o s t ( 1 9 4 0 ) h a d p r e v i o u s l y a l s o u s e d a v e r t i c a l a s s e m b l y o f fi ves u p e r i m p o s e d t a n ks , f r o m w h i c h t h e o u t l e t o f o n e t a n k w a s u s ed as t h ei n l e t t o t h e n e x t .

W h i ls t a l t e r in g t h e d e p t h t o w i d t h r a t i o in o n e s e n s e i n t e n s if i e s t h eo p e r a t i o n , it d o e s n o t o v e r c o m e t h e b a s i c p r o b l e m s o f in t e n si v e f is hr e a ri n g r e f e r r e d t o p r e v i o u s ly , a l t h o u g h i t d o e s h a v e t h e o b v i o u sa d v a n t a g e o f m o r e u s a b l e v o l u m e p e r u n i t a re a o f f l o o r sp a c e .

O x y g e n a v a i l a b i l i t yA s m e n t i o n e d in t h e I n t r o d u c t i o n t h e h y d r a u l i c c ha r a c te r is t i c s o f a n yf is h r e a ri n g t a n k d e s ig n i m p i n g e o n a ll t h e p r o c e s s e s w h i c h o c c u r w i t h int h a t t a n k . F r o m t h is c o n s i d e r a t i o n w e c a n s e e t h a t it is i m p o r t a n t t oh a v e f u l ly o x y g e n a t e d w a t e r in e v e r y p a r t o f th e ta n k , w i t h n o d e a da re as , a n d a m i n i m u m d i ss o lv e d o x y g e n c o n c e n t r a t i o n b e in g m a i n t a in e d .E l li s a n d W a s tf a ll ( 1 9 4 6 ) h a v e s t a t e d t h i s t o b e 5 p p m ( o r m g l i t e r - l ) ;h o w e v e r , t h i s is s p e c i e s s p e c i fi c .

S t u d i e s b y P r e v o s t ( 1 9 4 0 ) , D a v is ( 1 9 4 6 ) a s w e l l a s B u r r o w s a n dC h e n o w e t h ( 1 9 5 5 ) h a v e s h o w n t h a t e ve n d i s t r i b u t i o n o f t h e f i s h w i t h int h e t a n k h e l p s o x y g e n d i s t ri b u t i o n . T h e i n s t a n t a n e o u s l oc a l o x y g e nc o n c e n t r a t io n is d e p e n d e n t o n b o t h t h e ra te o f o x y g e n c o n s u m p t i o n


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F l o w d i s t r i b u t i o n s t u d i e s i n f i s h r e a r in g r a n k s - 1 1 13a n d o x y g e n i n p u t , w h i c h i n h y d r a u l i c te r m s m e a n s th e r at e o f ar riv alo f o x y g e n a t e d w a te r .

T h u s a n i m p o r t a n t e n g in e e ri n g h y d r o d y n a m i c d e sig n p a r a m e t e r ist o m a i n t a i n t h e d i s s o lv e d o x y g e n av a il ab i li ty t h r o u g h o u t th e ta n k .T h i s c a n b e d o n e b y : ( 1 ) i n c r e a s in g t h e w a t e r f lo w r a t e ; ( 2 ) i n t r o d u c i n go x y g e n o r a i r ( M i t ch e l l, 1 9 7 6 ; B O C , 1 9 7 6 ) ; ( 3 ) r e d e s ig n i n g t h e w a t e ri n je c t io n s y s te m ( L a r m o y e u x e t a l . , 1 9 7 3 ) .

M e c h a n i c a l c l e a n i n g d e v i ce sM o s t f is h t a n k d e s ig n s r e ly o n t h e i n tr i n s ic fl o w p a t t e r n s t o c a r r y a w a yu n e a t e n f o o d a n d s o li d w a s t e p r o d u c t s . O n t h e o t h e r h a n d , r e la t iv e l yf e w d e v ic e s h av e b e e n d e v e l o p e d , s o m e o f t h e m m e c h a n i c a l , f o r t h iss p e c if i c p u r p o s e .

S m i t h a n d J o n e s ( 1 9 7 0 ) d e v e l o p e d a b r u s h t h a t c l e a n e d t h e t u r n i n gv a n e s u s e d i n a r a c e w a y p o n d f o r d i r e c t i n g t h e f lo w o f w a t e r a r o u n dt h e c o r n e r .

M a c V a n e ( 1 9 7 9 ) d e s c ri b e d t w o m e t h o d s f o r c le a n in g s h a ll o w c yli n-d r ic a l t a n k s s u c h as m a n u a l v a c u u m i n g a n d l o w e r in g t h e - w a t e r le ve lw h i l e d e v e l o p i n g a c e n t r a l v o r t e x , i.e . f l u sh i n g . H a y n e s ( 1 9 7 5 ) u s e dt u r n i n g b r u s h e s a t t h e b o t t o m o f t h e t a n k t o s ti r u p t h e w a s t e m a t e r i a lsa n d k e e p t h e f is h o f f t h e b o t t o m , w h il st B o l t o n ( 1 9 5 7 ) h a d p r e v io u s l ye m p l o y e d a f l o o r s c ra p e r t o c le a r u p t h e b o t t o m o f a s e d i m e n t a t i o nt a n k .

I n o r d e r t o o b t a i n s e lf - cl e an i n g a c t i o n , th e m i n i m u m w a t e r c ir c ul a-t i o n v e l o c i t y a t a ll c r o s s - s e ct io n s o f t h e t a n k m u s t b e o f t h e o r d e r o f0 -2 f t s - l ( B u r r o w s a n d C h e n o w e t h , 1 9 7 0) .I m p o r t a n c e o f v e l o c i ty l e ve lsT h e l o c a l f l u id v e l o c i t y m u s t b e s u f f i c i e n t l y h i g h t o i n d u c e a s e lf -c l e a n i n g a c t i o n , b u t n o t t o o h i g h t o c a u s e s tr e s s i n t h e f is h ( B u r r o w sa n d C h e n o w e t h , 1 9 7 0 ). B u r r o w s h a s s t at e d t h a t t h e o p t i m u m v e l o c it yw i l l be s i ze and spec i e s spec i f i c .

T h e f lu i d v e l o c i t y a ls o a f f e c t s m e t a b o l i s m ; f o r e x a m p l e , p h y s i c a l l yc o n d i t i o n e d f i s h w e r e m o r e e f f i c i e n t f o o d c o n v e r t e r s t h a n s t o c k n o te x e r c i s e d ( P o s t o n e t a l . , 1 9 6 9) . O p t i m u m s w i m m i n g v e l o c it y fo rb e t t e r f o o d c o n v e r s i o n w a s i n v e s ti g a te d b y K u i p e r s (1 9 8 3 ) .


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t 14 A. Klaps is , R. Bur leyBurrows and Chenoweth (1955) highlighted the importance of

efficient food distribution in the fish rearing tank. They stated thatfood distribution was primarily a function of fluid velocity. The fluidvelocity is used to distribute food pellets throughout the tank/pond andinduce a rolling action on the pellets over the base of the tank suitablefor bottom-feeding fish. Suitable trea tment of certain feeds allows themto stay in the upper region of the water column for a longer period oftime but the unnecessary accumulation of food and waste productswill cause a further drain on the available oxygen. This emphasizes theimportance of designing a flow system which enhances the removal ofdetritus and uneaten tbod, whilst maintaining an acceptable level ofoxygen supply throughout the tank.

CONCLUSIONSIt may be observed that many problems arise from trying to simul-taneously satisfy several criteria.

The main problem in present fish rearing tanks lies in impropermixing and short circuiting with irregular flow patterns. From thisproblem others arise: the local depletion of oxygen in certain areas,for example, with a simultaneous build-up of ammonia and insufficientself-cleaning action for det ritus removal.Origin of problems

As described earlier, many types of fish tank exist, such as the circulartank, the raceway type, the Foster Lucas, the silo, etc. Many of thesetanks have been constructed in their particular geometry due to con-siderations of space utilization without taking into account any of theproblems previously mentioned.

Having decided the geometry of the tank that will be used, the waterinlet/outlet configuration design is the next step to be determined.Again, this decision may have been taken not on the basis of previousresearch or experimental work but for reasons of simplicity, expediencyand lack of understanding.

Thus, imperfect mixing and subsequent problems may easily occurdirectly as a result of the geometry of the tank and its incorrect inlet/outlet design.


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Fl ow dist ribu tio n studie s in f~sh rearing tanks - 1 1 15

Fig. 10.

WATERJINJECTON

4 I m . m- - I~ dlcxmOVERFLOW

FLUID DEPTH DEPENDS ON LENGTH OFCENTRAL STANDPIPE OF 10,15,25cms

Square f ish rearing tank outl ine d ue to Klapsis (198 3).

A n a l y s i s o f a s p e c i f i c p r o b l e m w i t h r e s p e c t t o a s q u a r e t a n kA s an e x a m p l e , a fi sh re a ri n g t a n k 1 m s q u a r e w i t h r o u n d e d c o m e r sa n d a c e n tr a l o u t l e t w a s i n v e st i g a te d f r o m t h e p o i n t o f v i e w o f f l o w ,m i x i n g a n d d i s t r i b u t i o n o f lo c a l f l u id v e l o c i ti e s . S u c h a t a n k s h a p e iss h o w n i n F i g . 1 0 .

F r o m t h e c o m m e r c i a l p o i n t o f v i ew th is p a r t ic u l a r g e o m e t r y g iv es a2 1 % i n c r e a s e o n u s a b l e s u r f a c e a r e a o v e r i ts c i r c u l a r c o u n t e r p a r t , b u t a tt h e e x p e n s e o f i n c re a s e d p r o b l e m s o f d es ig n f o r u n i f o r m c i r c u l a t i o n ,m i x i n g a n d d e t r i t u s r e m o v a l .

T h e w a t e r in l et d e si g n t h a t h a d b e e n u s e d p r e v i o u s l y a l lo w e d w a t e rt o e n t e r t h e ta n k a s y m m e t r i c a l ly a b o v e t h e s u r f a c e n o r m a l l y n e a r o n ec o m e r . T h i s p a r t i c u l a r w a t e r i n l e t d e si g n , i n c o n j u n c t i o n w i t h th es q u a r e s h a p e o f t h e t a n k , m e a n t t h a t t h e f r e s h w a t e r c o u l d n o t p o s s i b l yr e a c h a ll th e p a r t s o f th e t a n k , g i v in g g o o d m i x i n g a n d o x y g e n a t i o n ;i n d e e d , th e o p p o s i t e w a s b o u n d t o o c c u r.

D u e t o t h e l a rg e r f l u id d r a g f o r c e s n e a r t h e t a n k w a l l s a n d t h e b a s e o ft h e t a n k , t h e c l e a n in g e f f i c i e n c y w a s n o t v e r y g o o d , i.e . u n e a t e n f o o dp a r t i c le s a n d e x c r e m e n t w e r e n o t e a s il y t r a n s p o r t e d t o t h e o u t l e t . T om a x i m i z e t h e d r a g f o r c e s a t t h e b a s e , i t is n e c e s s a r y t o i n c r e a s e t h ev e l o c i t y g r a d i e n t a t t h e b a s e o f t h e t a n k s o t h a t t h e d r a g f o r c e s a re


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1 1 6 A. Klapsis . R. Burleysufficient to remove the majority of the faeces and uneaten food.In order to achieve this the single outlet was changed to a new outletwith four submerged pipes, one at each corner, discharging water atseveral depths from small orifices.

The standpipe and screen were modified so that they would encour-age the vortex flow patte rn developed by the new inlets.

The operational behaviour of this design of tank is the subject ofPart 2 of this study (Klapsis and Burley, 1984), the first part havingidentified the important parameters and their interrelationships asfar as intensive fish rearing are concerned.

APPENDIXResponse curve analysisResponse curve analysis is an important tool used in the hydraulicanalysis of flow and mixing in vessels used throughout the chemicaland process industries. Basically a stimulus, usually in the form of animpulse or step change in the fluid concentration, is applied at theinlet and at some point later the response of the system is recordedin the form of curves shaped for an input delta function, as we cansee in Fig. 6. Full details of the appropriate analysis are given byDanckwerts (1953) and Levenspiel (1966).

The curves shown in Fig. 6 due to Burrows and Chenoweth (1955)are not in the standard form of properly scaled variables as can beseen from a concentration maximum greater than unity. The generalshape of the response curves, however, do permit some qualitativeanalysis.

The curves show an early peak, which indicates by-passing, and along tail, which indicates dead water regions or regions of poor mixing.Of the three traces presented there is little to choose between FosterLucas and circular ponds, whilst the raceway pond, as might beexpected, shows enhanced mixing characteristics. The offset at zerotime indicates the relative velocities for a given holding value, but needsto be interpreted within the context of the particular vessel geometry.In terms of the mean residence time the fluid on average spent longerin the raceway, whilst Foster Lucas and circular ponds show a long tailin their exit age distribution curves.


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Flo w d is t r ibu t io n s tud ies in f i sh rearing tanks - 1 117A f u l l a n a l y s i s o f f l o w a n d m i x i n g in t e r m s o f b y - p a s s i n g , d e a d

v o l u m e s a n d w e l l m i x e d v o l u m e s i s g iv e n b y C h o l e t t e a n d C l o u t i e r( 1 9 5 9 ) , s u c h a n a l y si s b e i n g a p p r o p r i a t e f o r t h e q u a n t i t a t i v e e s t i m a t i o no f fi sh r e a ri n g t a n k f l u id b e h a v i o u r .

A C K N O W L E D G E M E N T ST h e c o n t r i b u t i o n o f M r A . R . O s b o r n e a n d M r B . T . L i n f o o t , D e p a r t -m e n t o f C i vi l E n g in e e r in g , H e r i o t - W a t t U n i v e r si ty , is g r a t e f u l l y a c k n o w -l e d g ed , as a re t h e H e r i o t - W a t t U n i v e r s i t y f u n d s w h i c h s u p p o r t e d t h isr e s e a rc h ; a l s o t h e a u t h o r s w i s h t o t h a n k M r D . K l a p si s w h o p r o v i d e da b u r s a r y f o r th e w o r k t o b e c ar r ie d o u t .

R E F E R E N C E S

BOC (1976) . Treatm ent of l iquid . U K P a t e n t 1 , 4 5 5 ,5 6 7 .Botton, J . (195 7). Improvem ents in or relating to scraping and scum ming apparatusfor sedimentation tanks. UK Pa te n t Spe c i f ic a t ion 782357 .Burrows, R. & Chenoweth, H. (1955). Evaluation of three types of f ish rearingponds . US De pa rtm ent o f th e In ter ior Fish an d Wi ld li fe Serv ice, ResearchR e p o r t 3 9.Burrows, R. & Chenoweth, H. (1970). The rectangular circulating rearing pond.The Progressive Fish Cu lturist , April, 167 -8 t .Buss, K., Graft, D. & Miller, E. (197 0). T rou t cultu re in vertical units. The Pro-gressive Fish Culturist , October , t87 -91 .Buss, K. (1975). Fish husbandry system. U S P a t e n t 3 , 91 6 ,8 3 4 .

Buss, K. (197 6). Fish husband ry sy stem. U S P a t e n t s 3 , 9 8 1 , 2 7 3 a n d 3 , 9 9 6 , 8 3 9 .Co bb, E. & Titco m b, J . (193 0). A circular pon d w ith central outle t for rearing fryand fingerlings of the salmonidae. American Fisher ies Soc . , 60, 121-3.Ch olette, A. & Cloutier , L. (195 9). M ixing eff iciency determ ination for con tinuo us

flow systems. Can. J . C hem. En g. , 37 , 105.Davis , H. S. (194 6). C are and diseases of trou t . U S D e p a r t m e n t o f t h e I n t e r i o r

Fish an d Wi ld li fe Service , Research Re po r t 1ZDanckwerts, P. V. (1953). Chem. Eng. Sci. , 2 ( I ) , 1 .Ellis, M. M. & Wastfall, B. A. (19 46 ). Determination o f w ater qu ality. US D e par t-

m en t o f the In ter ior Fish an d Wi ld li fe Service , R esearch Re po r t 9 .Finger, J . (1974). Vertical fish farm. U S P a t e n t 3 , 8 0 4 ,0 6 3 .Fruch tnicht , E. (1975 ). Fish growing tank. U S P a t e n t 3 , 8 7 0 ,0 1 8 .


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118 A. Klapsis, R. BurleyHaynes, R. (19 75 ). R ecirculation fish raising tank w ith cleanable filter. US Patent

3,886,902.Klapsis, A. (19 83 ). Investigation o f flow and m ixing effe cts in fish rearing tanks.MSc Thesis, Department of Chemical & Process Engineering, Heriot-Watt Uni-

versity, Edinburgh.Klapsis , A. & Burtey, R . (1984 ). Flow dis tr ibution s tudies in f ish rea ring tanks.Part 2.

Kuipers, J . (19 83 ). Increase in gro w th rate in Atlantic Salmon b y sustained exercise.Unpublished report.La rm oye ux, J . , Piper , R. & Ch enow eth, H. (197 3). Evaluation o f circular tanks forSalmonid product ion . The Progressive Fish Culturist, 35 (3) , 121-31.Levenspiel, O. (1966). Chemical Reaction Engineering. W iley , New York andLondon .

MacVane, T. (197 9). Fish culture tank. USPatenr 4,141,318.M itchell, R. (19 76 ). Performance characteristics o f po nd aeration devices. Proc. 7th

Annual Meeting ~orld Mariculture Society. 25-29 January , pp . 561-81.Moore, J . (1977). Fish growing tank and method. USPatent 4,003,337.Poston, H. , McCartney, T. & Pyle, E. (1969). The effect of physical condit ioning

upo n the growth , s tamina and carbohy drate metabolism on brook t rout . NewYork Conservation Department Fisheries Research Bulletin No. 31, pp . 25 -31 .(Cortland Hatchery Report No. 36.)

Prevost , G. (1940 ). A m etho d for increasing the capac ity o f trou t hatchery. TheProgressive Fish Culturist, 7 0 , 430-5 .

Smith, Q. & Jones, 1. (1970). Turning-vane brush for recirculating ponds. TheProgressive Fish Culturist, April , 119-20.

Surber , E. (1933). Observations on circular pool management. Trans. Amer. Fish.Soc., 63 , 139-43 .

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Klapsis 1984 Aquacultural-Engineering

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