Fishway system with turbine

Hydraulic and earth engineering – Fluid control – treatment – or containment – Flow control

Reexamination Certificate

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Details

C405S080000, C405S083000, C119S219000

Reexamination Certificate

active

06325570

ABSTRACT:

FIELD OF THE INVENTION
The invention is related to a fishway system and, especially, to a fishway system which includes a lock-type fishway.
DESCRIPTION OF THE RELATED ART
The main use of the fishways is to enable emigrating fish to pass over the barriers, normally power plant dams, and to rise upstream in a river system. Generally, there are two types of fishways. A fish ladder attempts to mimic a natural fishway. A fish ladder is difficult to be carried out if the height of fall is great. Then, a fish ladder will be a long, complicated, and expensive construction. Moreover, the implementation of a fish ladder is quite complicated for lower heights, too, and careful design is always required. A simpler solution is a lock-type fishway, the most common implementation of which is also known as the Borland fishway. An advantage thereof, in comparison with the ladder-type fishway, is that it is structurally much more simpler and may be implemented within a remarkably smaller space. The lock-type fishway is also more suitable to be applied on higher power plant dams.
In Finland, most of the river systems dammed up and equipped for production of electric power, are still lacking fishways, and the main reason for this are the expenses which the building of the fishways would result in. In addition to the design and building costs of the fishways the energy company also loses a remarkable amount of water-power, because the water discharge of the fishway is reduced from the electric power production. Accordingly, the operating expenses of the fishways are quite high. If a fishway is built, the aim is often to keep the flow rate of the fishway as low as possible, which makes the operation of the fishway less satisfactory. Obviously, the fishways were much more attractive for the energy companies, if an essential reduction in the loss of the electric power could be provided. An object of the invention is to provide a solution achieving such a reduction.
A starting point in the invention is the lock-type fishway, and therefore a simplified description of such a fishway, the operation of which is similar to the operation of a canal provided with locks, is presented in the following with reference to
FIGS. 1 and 2
. The fishway, which is located in connection with a dam structure
3
, includes a first part
9
from which a connection, opening
12
, leads to lower water
2
. The opening is provided with a gate
13
. A second part
4
is connected to upper water
1
via an opening
6
in a wall
5
. The second part
4
is separated from the upper water by a gate
7
, by means of which water flow to the fishway may be regulated. A rising pipe
8
connects the first part
9
to the second part
4
. The first part
9
is advantageously container-like, closed by walls
10
,
11
from every side, and the second part
4
is basin-like, as is shown by the schematic sectional drawings of FIG.
1
. In operation, water is discharged via the first part
9
to the lower water
2
for luring fishes from the lower water through the opening
12
to the container-like part
9
. Water may be discharged directly from the upper water by suitably adjusting the gate
7
(
FIG. 1
) or, for example, brought by pumping from the lower water. When a long enough time is spent for luring fishes to the container
9
, the opening
12
is closed by the gate
13
, as is seen in FIG.
2
. At the same time the gate
7
is opened, whereby first the container
9
and then the pipe
8
are filled with water. Fishes, which are accustomed to swim under a small pressure close to the water surface, like to keep themselves close to the water surface and thereby rise via the pipe
8
to the basin
4
from which they are able to pass to the upper water. The operation cycle of this type of fishway may be 1 to 4 hours, for example.
Several problems are encountered also when accomplishing a lock-type fishway. For example, if the height of fall is great, a disadvantageously forcible and turbulent flow is caused in the lower part of the fishway when the water is discharged from the fishway. To overcome this problem, the use of energy absorbing or dispersing diffusor means in the flow openings of the fishway is proposed in SE 467216 B. In FI patent 55071 a solution is presented in which the water of the basin to which the fishes have been lured is forced to be transferred, by pumping or air pressure, to the upper water the fishes being transferred therewith. However, no fishway solution is presented in above documents or elsewhere which would be able to essentially reduce the water-power loss caused by the outcoming flow of water great enough for luring fishes effectively to the fishway.
SUMMARY OF THE INVENTION
For realizing the above and other objects of the invention, the fishway system of the invention is characterized in what is claimed in claim
1
of the attached claims. Other claims define different embodiments of the invention.
The main advantage of the invention is that the discharge of water needed for luring fishes to the fishway is continuously producing energy, and so the loss of water-power is kept low. Remarkably great discharges of water may be used in the fishway and the performance of the fishway may thereby be improved without raising the operational expenses unacceptably. At the same time the structural simplicity of the lock-type fishway may be maintained. The outcoming openings of the fishway are advantageously vertical and are easily found. The fishes must not search for an opening at a certain depth of water. The fishes find also the rising channel easily, and the risk of remaining under high pressure is small. Especially, if the rising pipe is steep, a lot of light is got to the pressure chamber, which makes the rising of the fishes easier.


REFERENCES:
patent: 3038760 (1962-06-01), Crooke
patent: 3232060 (1966-02-01), Windle
patent: 3293862 (1966-12-01), Harding
patent: 3772891 (1973-11-01), Raistakka
patent: 4437431 (1984-03-01), Kock
patent: 5673449 (1997-10-01), Henriksson et al.
patent: 6155746 (2000-12-01), Peters
patent: 55071 (1979-05-01), None
patent: 4149306-A (1992-05-01), None
patent: 4182504-A (1992-06-01), None
patent: 427 941 (1983-05-01), None
patent: 467 216 (1992-06-01), None

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