Note: Descriptions are shown in the official language in which they were submitted.
lX90~
FLOATING TIDAL POWER STATION FOR PLACING IN SEA AND
RIVER CURRENTS FOR GAINING ENERGY
The invention relates to a floating tidal power
station for placing in sea and river currents for
gaining energy and is of the type described in the
introduGtion to claim 1.
There are known various types of power stations
utilising sea currents, river currents and tides by
applying turbines placed in the water current.
Utilisation of the energy in flowing sea or river
water or in tides requires a power station which is
arranged in such a manner that it will automatically
adapt itself to the changing direction and speed of
the water current and which will moreover operate
satisfactorily even if there are great variations in
the depth of water due to the tide and weather
conditions in general. Furthermore, the station
should be dependent on the depth of water so that it
may find use within a depth range of 6 metres to 4
kilometres.
It is the ob~ect of the invention to provide such a
floating power station affording a very substantial
energy take-up and whlch will always adapt itself to
the water flow and to the turn of the tide and which
is designed in such a manner that it is particularly
simple to maintain and repair.
This is achieved by designing the tidal power station
according to the invention as disclosed in the
characterising part of claim l. By inspection, repair
~k
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work or replacement of one or more of the turbines,
the entire turbine formation is pulled up into the
water surface within the area limited by the ring
pontoon where the waves are substantially calmed by
the ring pontoon which for example obviates the need
for awaiting calm weather before doing repair work.
Furthermore, the ring pontoon surrounding all the
turbines offers favourable working conditions so that
it is not necessary to sail an auxiliary vessel or a
barge crane out to the power station in order to be
capable of commencing repair work or inspection.
Optimum utilisation of the ring pontoon is achieved
by designing the power station according to the
invention as disclosed in the characterising part of
claim 2. It is possible to mount a great number of
turbine units in the power station thereby providing
a substantial power take-up and so running the
station profitably. The shape of the ring pontoon
means that the rear part may serve as a suspension
for the turbine formation which is almost weightless
in the water; the front part serves as a mooring part
and the sides serve to be capable of supporting the
swung up turbine formation during towing and
serviclng.
To ensure that the ring pontoon is correctly
positioned in the water so that the propeller plane
of the turbines is always at right angles to the
direction of the water current the power station
according to the invention is preferably designed as
disclosed in the characterising part of claim 3. It
is thus possible to have an anchor point far below
the water level and all forces directly to the anchor
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point around which the entire power station may
swing. The result is that the ring pontoon will not
take a lopsided position in the water even by a very
substantial energy take-up in a strong water current
such as a tidal current between high and low tide.
The power cable is carried down through the bitt
from slip-ring contacts at the top. When connecting
and disconnecting the wire assembly means, a wedge
arrangement retaining the wire assembly means may be
manoeuvred from inside the mooring bitt.
Additional stability towards powerful changes in
current etc. is achieved by designing the power
station according to the invention as disclosed in
the characterising part of claim 4. In this manner
all tractive forces are transmitted to the anchor
warp without problems and the power station will
always rest quietly and stably with the ring pontoon
planely in the water surface.
By designing the securing of the internal warps as
disclosed in the characterising part of claim 5, a
simple way of mooring the power station to the
mooring bitt is obtained.
By designing the power station according to the
invention as disclosed ln the characterising part of
claim 6, it is possible in a simple manner to place
the entire turbine formation in a position permitting
service and repair work to be done and back again in
its operational position using quite simple means. It
is possible to carry out all these operations from
the power station without any help from auxiliary
vessels, barge cranes etc. and without any
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significant change of the stability of the floating
power station.
By designing the power station according to the
invention as disclosed in the characterising part of
claim 7, it is possible to achieve an arrangement of
the turbines on the central beam which is correct
relative to power and moment, Connection and
disconnection of the turbines powerwise should take
place in pairs but purely physical replacement of for
example a damaged turbine may without problems take
place separately.
Preferably the power station according to the
invention is designed as disclosed in the
characterising part of claim 8. It is thereby
possible to locate all auxiliary equipment and
service equipment on and inside the ring pontoon. It
is possible to carry out any form of repair work or
maintenance on site without any outside help. The
ins$de of the ring pontoon serves as a housing and as
a transport route for installations and equipment.
The purpose of the crane is to lift and mount the
internal ring assembly of the anchor warps over the
mooring oitt and to service and replace the turbine
units which are almost weightless in the water, and
moreover to operate as lifting gear for spares and
other appliances.
The invention will now be further explained with
reference to the drawing showing a preferred
embodiment of the invention wherein
Fig. l is an inclined top view of the aggregate
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hydroelectric power station and in its
operational position when producing
electricity,
Fig. 2 is a vertical plane section of the power
station along the line II-II in Fig. 3,
Fig. 3 is a top view of the power station and
with the entire turbine formation in
position for repairs and/or maintenance,
Fig. 4 is a partial section on a large scale
along the line IV-IV in Fig. 3, and
Fig. 5 is a detailed view of the wire connecting
means at the lower end of the mooring
bitt.
The drawing shows the floating power station anchored
to two anchors 1 which are preferably aligned
parallelly to the main direction of the current so
that in general only one of the anchors will hold the
power station up against the current.
The anchor warps 2 are connected to a mooring bitt or
upright buoy 5 containing air chambers for buoyancy.
Between the warps 2 there is provided an auxiliary
warp 32 preventing the slack warp from hitting the
turbines due to the action of the current. At its
lower end on a level with the turbine beam 11 the
bitt 5 has a wire connecting link 6 with a nylon
~ournal bearing so as to permit the entire power
station to swing around the bitt 5 and as will be
further explained in connection with Fig. 5.
1 2~0~1
The power station comprises a rectangular ring-shaped
floating pontoon 3 which via a front pontoon 9 and an
anchoring means 24 is anchored to the bitt 5. In
front of the bitt 5 there may be arranged an
independently floating buoyancy pontoon 18 which by
solid struts 14 is secured to the front pontoon 9 on
either side of the bitt 5. A steel wire 31 extends
from the buoyancy pontoon 18 to the connecting link 6
from which steel wires 7 as strapping warps extend to
the ring pontoon 3 and from which further steel wires
16 as tension distributing warps extend to the
central beam 11 in the turbine formation.
The turbine formation itself comprises a number of
preferably uniform water power turbines or propeller
driven generators 21 which by means of turbine guides
10 are arranged for example in pairs on either side
of a common central and hollow beam 11. The beam 11
is suspended in upright columns 13 which by means of
hinges 30 are suspended in the long side of the ring
pontoon 3 situated opposite the mooring side.
For securing and for relieving pressure on the
turbine beam there is moreover provided a main beam
in a common turbine lattice beam, transverse
struts 12, for example in the form of steel wires,
lattice diagonals 22 and inclined columns 17.
Fig. 2 shows how the mechanical power is transferred
directly from the central beam 11 via the tension
distributing warps 16 to the anchor point 6 at the
lower end of the bitt 5.
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The ring pontoon 3 is furthermore provided with a
crane track or rails 19 for a mobile crane 8, an
inner circumferential catwalk 20 with fender and
outer fenders and mooring means 23.
Fig. 1 shows how the power cable 4 extends down and
out through the bottom of the bitt 5 at the top of
which there may be designed sliding contacts or
similar contact means so that the cable 4 between the
bottom 36 of the mooring bitt and the power station
is not twisted with the changes of current and other
manoeuvring of the power station.
Fig. 1 shows the station in its normal position
producing electricity on all turbines, in the shown
example twelve turbines. In case of repair or
maintenance work the entire turbine formation is
swung up as shown by a broken line in Fig. 2 or by a
solid line in Fig. 3~ This manoeuvring is performed
by first feathering and stopping all propellers, then
air is blown into buoyancy chambers in the beam 11
whereafter it is possible by pulling wires in a
generally known manner to swing the turbine formation
in its hinges 30 to the shown position whereupon the
beam 11 is locked at both ends to the ring pontoon 3
by means of the locking means 25.
The detailed view in Fig. 4 shows the operation of
the service crane 4 on the ring pontoon 3. The ~ib 26
of the crane has a supporting leg 27 which by means
of a locklng mechanism 29 may rest on the turbine
guide of the turbine to be repaired or replaced. It
is then possible by means of the crane having two
crabs 28 to replace the turbine 21 by the spare
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turbine 21'. Cable ~oints etc. from the turbine unit
to the power station are disconnected and the turbine
21 is released and lifted a short distance by means
of the crane. The top or the bottom of the unit 21 is
connected to the crab on the ~ib 26 outside the ring
pontoon and by slackening and lifting the unit 21 is
carried outside the ring pontoon 3 in a movement down
below the pontoon. The same operation is carried out
with the spare turbine 21' but in reverse order when
same is arranged in its place.
The mooring to and the connection of the internal
warps to the mooring bitt 5 will now be further
described in the following with reference to Fig. 5
of the drawing. The mooring bitt is provided with a
ring-shaped bottom 36 to which the anchor warps 2 are
secured. Before placing a power station in the water
current, the anchors 1, the warps 2 and the hollow
vertically floating bitt 5 are first arranged.
When a power station is to be towed out to the
mooring bitt 5, this is done with the turbine
formation in its llfted and locked position. All
internal warps, i.e. the warps 7 and 16, are in
beforehand secured to the cylindrical wire connecting
means 6 which during the towing rests on the front
pontoon 9. By means of the crane 8 the cylinder 6 is
lifted e.g. by hooking on the vacant fitting 35. When
the power station has been towed in place, the wire
connecting means 6 is slid down over the bitt 5 until
it rests on the bottom part 36 whereupon a solid
steel ring 34 is lowered and locked to the bitt 5,
e.g. by an extending wedge arrangement 33 which can
be operated from within 5. The means 6 can now freely
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turn relative to the bitt 5 because there are
arranged nylon ~ournal bearings and discs between the
means 6 and the bitt 5.
Then the fittings 24 are connected to the top of the
bitt 5 together with the internal cable 4' and the
entire floating power station is now anchored and
connected in such a manner that it freely swings
according to the direction of the water current.
By disconnecting the power station from the bitt 5
the above measures are taken in reverse order but not
till the turbine formation has been swung up and
secured to the locking means 25 and the cable
connection 4' to the top of the bitt 5 has been
disconnected.
A statlon according to the invention may for example
have the following dimensions:
Anchors: Reinforcèd concrete caissons 30 x 15 x 7 m,
weight approx. 18,000 tons.
Ring pontoon: Diametre 4 m. External measurements:
50 x 150 m.
Turbines: 12 asynchronous generators of 740 kW each.
Propeller: Diametre 18 m.
Presupposing a tidal mean flow rate of 1.3 - 1.9
m/sec and an energy gain of 44% of the energy in the
water current during working time, the station will
be capable of supplying 33 mill. kWh/year.
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Depending on the water depth, the turbine formation
may have one or two rows of turbines. By low current
depths between 6-25 m one row of turbines will be
most advantageous. The turbines shown on the drawing
are upstream turbines but there is of course nothing
to prevent the use of downstream turbines.
