CA1043273A - Fish removal screen for intake channel - Google Patents

Abstract

ABSTRACT

A traveling water screen includes rotating sprockets elevated above a water intake channel. An endless series of screens and intermediate elongated water-tight buckets hang downwardly in the channel and operate over the rotating sprockets. The screens intercept the fish in the channel and the buckets elevate the fish which are dumped from the buckets as they pass over the sprockets. Water sprays are provided to push the fish toward a receiving trough by which the fish may be conveyed to a holding pond or returned to the stream or body of water.

Description

This inventi~n relates to separating means placed in a channel confining a flowing stream to prevent fish from passing downstream in which the strainer is a movable end-less foraminous belt (21~-160).
Water intake systems for electric power generating plants and other industrial purposes generally include a series of bars forming a grate which first excludes large objects, timbers and the like; this grate may be followed by a bar screen which is mechanically cleaned to remove debris of a smaller size; the flow is then usually passed through a final screen of a mesh opening of only 3/8" or possibly 1/4". This screen is cleaned with a backwash spray and is generally of the type referred to as a traveling water screen. These units are particularly adapted for use where the level of the intake flow varies considerably due to natural causes.
Such a unit comprises a series of rectangular screens which form an endless loop hanging in the intake channel from an upper housing. Such units are shown for example in United States Patent Nos. 1,593,169; 1,781,223; 1,910,860;
and 1,942,381.
These units are generally operated intermittently.
Tha~ is, between cleaning cycles, the screens remain station-ary in the channel. As the screens are blinded by the accumulated debris, the level of the flow downstream of the unit is lowered until a predetermined time has elapsed or a given reduced level is reached. The screens are then rotated in the sense that the already cleaned screens are placed forwardly and the blinded screens are elevated into the spray housing for cleaning. The debris to be removed is ~, ~43Z73 essentially that which is "plastered" against the screens and whatever remains on the ledges of the screen frames.
United States Patent Nos. 2,804,209 and 2,851,162 show traveling water screen units which include trays or troughs specifically for removing or elevating fish from the flow.
The fish are flushed into a lower fish-receiving trough and the upward moving screens are then backwashed into an upper debris-receiving trough. Such removal of the fish from the ;, upward moving buckets is believed to be unreliable and dama--ing to the fish and is particularly inefficient if the units are to be operated continuously. That is, they cannot operate intermittently if any fish are in the trays or troughs and survival of the fish is the objective. It shou7d also be mentioned that the drive means of such units generaily ;~
elevate the screens in the order of 10 feet per minute.
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Having in mind that the fish are generally exhausted in the-r attempting to avoid the apparatus, it will be understood th--~
their environment between the time they leave the water and reach the receiving trough affects their survival.
The use of inclined screen belts or rotary drum screer~
have also been proposed for fish removal but such proposals j have not given full consideration to the condition and `!
activity of the fish in front of the screen. It should be emphasized that the fish when first encountering the screer.
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;are fully able to escape even the upward moving buckets. ~-Generally only the fish which are fully exhausted will be removed from the stream and when they find themselves out o water, they may die of shock or, with a last burst of ener~y, flip themselves back into the stream and eventually die after this sequence is repeated some number of times. It is thus .. . .

2 -~43;~73 necessary th.at ~uckets be provided and designed to catch the f~sh ~e,ore the~ are exhausted.
Because the fish can swim in and out of the buckets , movin,g upwardly in the flow, they are generally only caught .:
~y the buckets as th,ey emerge rom the flow. However, with their last burst of energy, they can flip out of the buckets, .. :
an.d a sufficiently high for~ard lip is thus required. Some ; , ~ater must be caxried by the buckets to a depth which allows ., - th.e fis~ to survive, and this requtres that the lip extend well above this ~ater level. However, this high lip makes it difficult to flush the fish from the buckets as suggested by ;.
the PrLor art, at least without damage to the fish. The prior , ~ '~
art ~as no Provision for these requirements. " .
. The invention in one aspect comprehends the method of : .
nondestxuctively removin~ fi.sh rom the 10w in a channel wh.~ch'~ncludes. moving an endless serieS of alternately arranged .~' scree~$ ~nd ~uckets in the ch.annel so that th.e ish are intex- . ~
cepted ~y upwardly moving screens and are removed from the ~ -, cha~nel flo~ b~ the buckets, inverting the buckets above the 2a channel so t,hat th.e ~ish tumble over the preceding downwardly ;.
mo~n~ ~creen~, Providin~ a receiving trough above the channel ~,~;-' adiacent to th.e path of the dow,nward moviny screens to catch such'fis~ and providin~ a flo~ o~ ~ater in the trough. for -, immed~atel~ transporti,ng the fish. toward their intended rece~v~n~'~eans~ ' -',~ The inventio~ in another aspect comprehends an apparatus :~
fox t~e ~ondestructive removal o~ the fish from the flow. of wa~er .
', in a ch~nnel~ the apparatus as installed havin~ an upstream ~ront side and a downstream rear side and comprisin~ rotational ~' dri~e'~ea,ns elevated above t~e channel, A lower return means , is at the b9ttom of the channel, and spaced vertical front ~'.
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~ gu~de~ ~re at each side of the channel, A series of spaced :

., : ~ ~ater-tight Puckets and intermediate rectangular screens are . : :
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~ 3 _ ~3~3 together pivotally in-terconnected to Eorm an endless loop extending over the upper drive means and beneath the lower return means. The buckets and screens are supported by the drive means and are disposed so that the buckets and intermediate screens move upwardly between the front guides with the buckets upright - ;
and the buckets and intermediate screens move downwardly at the rear of the apparatus with the buckets inverted. A fish-receiving trough extends over and across the channel at the rear of the apparatus and is disposed to receive the fish which are emptied from the buckets as they are inverted over the drive means and which fall over and past the screens at the rear of the apparatus.
More particularly, the fish removal screen unit of the invention is intended or adapted for continuous operation and includes water tight buckets. As the buckets pass over the upper drive sprockets the fish are dumped therefrom and tumble downwardly over the inclined screen and directly into the fish-receiving trough. A low-pressure flow of water may be provided to flush the fish from the underside of the inverted buckets or screen frame members with some impetus so that they are certain to fall into the fish-receiving trough.
The screen is intended for continuous operation, that is, while ~
any number of fish are in the intake flow and require removal. ;
The screen unit may also include a lower spray and receiving trough for the debris. This spray would be generally a high pressure spray to assure full cleaning of the screens.
FIGURE 1 is a side elevation of the fish removal unit in a channel. Portions of both are broken away and sectioned to ., , ~ .

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~43Z73 show details of the unit.
FIGURE 2 is an enlarged section of the fish~receiving trough deflectox plate and of an approaching inverted ~ucket.
FIGU'RE 3 is a view of the rear of the unit which is set in the channel shown in section. Portions of the housing are broken away and sectioned to show the upper and lower fish-receiving and debris-receiving troughs.
FIGURE 4 is an enlarged side elevation of one of the two upper sprockets and shows in section details of the screens and their supporting frames and the upper spray apparatus for assisting the fish into the fish-receiving trough.
The concrete channel showr, includes the vertical side- ~ -walls ll and bottom l2. ~he frame of the apparatus as installed in the cnann~l includes ~he 1 3WG~ rcturn s~ction 13 which rests on bottom 12. The front and rear posts or vertical guides 14 and 15 disposed at each side of the ! channel extend from lower section 13 upwardly into the open-ing in the concrete slab 16 which extends over the channel.
The upper frame includes the intermediate section 17 sup-ported by the guides~14 and 15 and the upper drive section 18.
; ~ The threaded rod l9 and capstan 20 at each side of the drive section 17 provides the vertically adjustable support of the bearings 21 in wh~ich the drive shaft 22~is turnable. Two spaced sprockets including the sprocket 24 shown in FIGURE 4 are fixed on shaft 22 which is driYen by the motor 25 and l ~ - . . ..
reducer 26 through a chain and sprocket drive, not shown.
The 1ower return section 13 includes a spaced pair of hexagonal wheels including ~he wheel 27, which are turnable ,., ~ . ~: .
l~ 30~ on the~shaft 28. Endless chains, not shown, for the support -., .

~ iO913273 of the screen frames 30 are trained over the corresponding sprockets 24 and wheels 27. The chain at each side of the apparatus includes an upward run which operates in front guides 14 and a rearward downward run which operates in the rear guides 15. United States Patent No. 2,428,757 shows a particularly suitable means of securing each end of frame 30 to the respective link of the chain so that each two adjacent frames are pivotally interconnected.
Frames 30 carry the buckets 31 and support the screens 32. Each frame 30 includes the upper and lower crossmembers 33 and 34 and the curved plates 35 which join the correspond-ing ends of the crossmembers. As shown in FIGURE 4, the lower member 34 includes a trailing flange 34a ~hich extends in front of the upper member 33 of the following frame 30. The small gap therebetween is in alignment with tne axes articulation of the respective links to which the frames are connected so that the width of the gap is substantially un-.
changed by the relative pivotal movement of the frames.
The woven wire screens 32 are stretched across their frames~30 and secured thereto in any suitable manner. Asshown, the lower margin of each screen 32 may extend behind the bucket which is supported by its frame. The bolts 36 shown ~or securing the buc~ets to frames 30 may, of course, require sealing to prevent the loss of water from the buckets.
n the~operation of the apparatus, the water in thè
channel~passes through the scxeens 32 which are moving up-ward bett.een guides 14. Minimum clearances are provided so !
that there is no appreciable flow around the upward moving ~;
:
iscreens or through the lower frame section 13. Where the A 30 rear guides 15 are not required, the clean flow may pass ,~ ' , . ' .

- ` 1¢)43~73 around as well as through the downward moving screens at the xear of the apparatus.
The debris which is intercepted hy the up~ard moving screens 30 is held against the screens by the flow there-through until the screens move upwardly out of the water.
As the screens move out of the water, the debris rem;ins attached to the screens although some amount will drop into the buckets 31. However, substantially all of the fish pushed against the screens, fall and remain in the buckets, excepting the very active fish which might flip themselves back into the flow for the time being. That is, the mesh o~
the screens should be small so that very few fish become lodged in the screens. --As the screens 32 and buckets 31 move upwardly over spr~ck~s 2~,- 2a~h 'uc~et ls turned and emptied of water.
Some number of seconds thereafter, the bucket, having passed over shaft 22, is inverted to dump the fish onto the screen over which the fish may tumble over the screen and into the receiving trough 41 at the rear of the apparatus.
Additionally, a low-pressure water supply line 45 controlled by valve 46 may be connected to the header 47 which extends between sprockets 24. The header 47 is fitted - -with~a~series of nozzles 48 and deflector 49 which direct a -spray or flow of water through the downward moving screens 32 to dislodge any fish on the underside of the inverted buckets 31 or strips S0. The reference here to the undersi~e ~ -, ~ ~ of a bucket includes also the overlying projecting portion of lower member 34.
The use of spray nozzles 48 may be required only unde~
some conditions, such as where many smaller fish are -:

~ 6143~73 encountered. Further, and except as will be described, spray from nozzles 48 should dislodge a minimum of debris into trough 41 so that conveying or sluicing the fish from trough 41 into a suitable holding pond or tank or back to their natural habitat is rela~ively simplified.
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It is recognized that construction of the frames 30 as shown is such that the fish tumbling over the screen may be caught in the gap between frames on the inverted adjoin-ing crossmembers. Accordingly, the strip 50 are attached to the undersides of each crossmember 33 to shield the gaps.
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The deflector plate 52 extends from one side of trough 41 and may include or be provided with a resilient strip 52a which :-forms the lip of the plate. Strip 52a is adjustable so that the lip may be located in close alignment with the downward lip of the invert~d buckets.
The sareens 30 which have passed trough 41 are then cleaned of debris by high pressure sprays. The debris-receiving trough 53 is provided to receive such debris and includes a similar deflector plate 54O Preferably two headers 55 and 56 are similarly provided with spray nozæles and are -indivi~dually controlled by the valves 57 and 58. The two . . .. .
! ~ : headers are spaced so that when both valves are open, and although the spray from one header may be blocked by a bucket 31 or by crossmembers 33 and 34, the spray from the other~ header will not be blocked. This assures that de~ris ., , .. ~ , which; might~fall past or between the deflector plate 52 and a screen 30 will be deflected by such spray from either .~ header 55 or 56 and will not be allowed to fall past de-flector plate 54 and into the screened flow behind the 30 ; apparatus.

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1~43Z73~
It should be understood that the present invention includes the apparatus shown and described but including only the upper trough 41 for receiving the fish where separate debris removal is not required. That is, lower trough 53 and the intermediate section 17 with spray headers 55 and 56 could be omitted. The drive section 18 would then, of course, rest directly on the posts or guides 14 and 15.
The high pressure spray required for the effective xemoval of debris must generally be over 80 psi and may be as high as 120 psi in some installations. In contrast, the low pressure spray for the removal of the fish must be in the order of 10-20 psi. However, it is noted again that most if not all of the fish will fall by gravity into their -~
re~eiving trough 41.
It is also i~por~ant to nvte that tne appara~us as described is entirely adapted for the continuous operation which is required for effective fish removal. In particular, . . . . , - . .
for example, it is not required that the high or low pressure -sprays be turned on and off by valves or that any other mechanisms be provided to operate in time relation to the movement of the screens. - -The high pressure spray operating continuously while the ~creens are moving provide the water in trough 53 for carry~
ing the de~ris to wherever it 1s to be transported. However, a minimum water depth is required in trough 41 for the fish at -all times and the water spray from nozæles 48 may provide some of the water necessary to maintain the depth refe~red to.
Alternatively, a considerable flow of water from nozzles 48 ~ -could provlde the entire water supply needed for transporting the fish in trough 41 and might be preferable so as to '.' i ., ~, 9 -- . .

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~V4~73 : -gently flush the fish from the inverted buckets as described.

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Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Apparatus for the nondestructive removal of the fish from the flow of water in a channel, said apparatus as installed having an upstream front side and a downstream rear side and comprising rotational drive means elevated above the channel, a lower return means at the bottom of the channel, spaced vertical front guides at each side of the channel, a series of spaced water-tight buckets and intermediate rectangular screens which are together pivotally interconnected to form an endless loop extending over said upper drive means and beneath said lower return means, said buckets and screens being supported by said drive means and disposed so that the buckets and intermediate screens move upwardly between said front guides with the buckets upright and the buckets and intermediate screens move downwardly at the rear of the apparatus with the buckets inverted, and a fish-receiving trough extending over and across the channel at the rear of the apparatus and disposed to receive the fish which are emptied from the buckets as they are inverted over the drive means and which fall over and past the screens at the rear of the apparatus.

2. The apparatus of claim 1 which further includes an inclined deflector plate extending upwardly from said trough and having an upper lip extending alongside the downward path of the buckets.

3. The apparatus of claim 2 wherein the portion of said deflector plate which includes said upper lip of the plate is of a flexible material.

4. The apparatus of claim l which includes water supply means located above the trough and disposed to direct a flow of water through the downward moving screens and over the underside of the inverted buckets so as to flush gently any fish lodged thereon into said trough.

5. The apparatus of Claim 1 wherein each of said screens includes a rectangular frame member and wherein the adjacent members of adjacent screens have operating gaps therebetween, and each such frame includes a strip which projects such that the several strips extend under the gaps between the screens moving upwardly and over the gaps between the screens moving downwardly to prevent the fish from becoming entrapped therein.

6. The apparatus of Claim 5 which includes water supply means located above the trough and disposed to direct a flow of water through the downward moving screens and over said strips and the undersides of the inverted buckets.

7. The apparatus of Claim 4, 5 or 6 which includes a trash-receiving trough extending over and across the channel at the rear of the apparatus and below the fish-receiving trough and which apparatus further includes spray means adapted to be connected to a supply of water under high pressure and located below said fish-receiving trough and disposed to direct a spray of water through the screens to push trash from the screens Whereby said trash falls into said trash-receiving trough.

8. The apparatus of Claim 1, 2 or 3 which includes a trash receiving trough extending over and across the channel at the rear of the apparatus and below the fish receiving trough and which apparatus further includes spray means adapted to be connected to a supply of water under high pressure and located below said fish receiving trough and disposed to direct a spray of water through the screens to push trash from the screens whereby said trash falls into said trash receiving trough, the arrangement being such that any debris falling past the fish receiving trough will be diverted by said high pressure spray means into the trash receiving trough.

9. The method of nondestructively removing fish from the flow in a channel which includes moving an endless series of alternately arranged screens and buckets in the channel 50 that the fish are intercepted by upwardly moving screens and are removed from the channel flow by the buckets, inverting the buckets above the channel so that the fish tumble over the preceding downwardly moving screens, providing a receiving trough above the channel adjacent to the path of the downward moving screens to catch such fish and providing a flow of water in the trough for immediately transporting the fish toward their intended receiving means.

10. The method of Claim 9 which includes directing a flow of water through the downward moving screens to push the fish well over the gap between the trough and downward moving screens.