The invention relates to a tidal-driven seawater pump, in accordance with the preamble of claim 1.

Background

The invention is related to a tidal-driven seawater pump which utilizes the energy in tidal water. The height difference between hight tide and low tide vary substantially between different geographic locations. In the Oslo fjord, for example, the difference between high tide and low tide is less than one meter, whereas the difference in Vadso is less than four meters. At other locations in the world, the difference is substantially higher, such as 16 meters in Nova Scotia. The tide represents a large energy resource which is being utilized to a low degree, but there are both electric power plants and seawater pumps that is utilizing the tide.

CN Patent publication no. 103397996 discloses a tidal-driven seawater pump, arranged to pump seawater to a position higher than the sealevel at falling tide. The tidal-driven seawater pump comprises a large byouyance tank moored to the seabed by rope through connectors. At the upper end, a water-filled hollow buoy is arranged, connected to a piston. However, the tidal-driven pump only operates during falling tide.

US Patent 8,105,052 describes a pump mechanism utilizing wave and tide energy to, among other things, pump water to desert areeas, produce power and remove pollution from the sea. The pump mechanism comprises a buoy attached through a chain or cable to a piston accomodated in a cylinder. During rising tide, the cavity in the cylinder under the piston is filled by seawater through non-return valve. During falling tide, seawater is guided in the cylinder out through outlet non return valve. This pump as well only operates during falling tide.

WO 2008/090302 A1 describes a water pump operated by wave energy. The water pump does in one embodiment consist of a column 22 piled down into a seabed 31. A pipe cylinder 9 is mounted atop the cylinder 22 and exhibits upper 7 and lower 14 inlet valves to suck water into the pipe cylinder by power driven by vertically oscillating movement of a buoyance means 2 having weight means 3. Water is forced out of the pump 9 through an upper outlet valve 8 or a lower outlet valve 13 and out through outlet pipe 17. In an alternative embodiment, the column is replaced by a socket 29 of metal or concrete having a buoyance body 21. The arrangement of the upper and lower inlet and outlet valves makes the pump to work in a double-acting manner. The embodiments in the figures 2A-6A show a column attached to socket 29 by cettle 28 or a schackle connection 30. An arrangement of this type subjects the water pump to large forces from waves and current, and will hardly survive in rough sea. Another disadvantage is piston 12 stroke in the pipe cylinder 9 cannot be dimensioned for optimal operation in areas having large tide level variations. A similar challenge arises if the water pump is to be used in different locations having varying tide differences.

Object An object of the invention is to provide an improved tidal-driven seawater pump, where the seawater pump can operate in rough sea with a lot of waves. Another object of the invention is to provide such a seawater pump that can be adapted to different tidal differences.

The invention

This object is achieved by a tidal-driven seawater pump in accordance with the characterizing part of claim 1. Additional advantageous features appear from the dependent claims.

The invention is related to a tidal-driven seawater pump having a socket arranged to rest upon the seabed. The seawater pump comprises: a buoyance means connected to a piston through a substantially vertically extending stiff connection means, wherein the piston is accomodated slidably in a closed cylinder having a top wall and defining a closed compartment, wherein a seal is provided along the periphery of the piston and the cylinder wall, and wherein the cylinder at its ouside exhibits an inlet for supply of seawater from the environments to either an upper inlet valve at the top wall or a lower inlet valve and further to the internal closed compartment, and an outlet to allow seawater accommodated within the internal compartment of the cylinder to be pumped to a reception onshore or at the sea surface, either through an upper outlet valve or a lower outlet valve.

In accordance with the invention, the buoyance means is accommodated slidably within a substantially vertically extending elongate protective housing having an upper compartment with an upper open end, and having a lower end delimited by the top wall of the cylinder. The protective housing is provided with a number of flow apertures to allow exchange of seawater between the environments and the internal compartment of the protective housing. The buoyance means is formed of a solid material with negative buoyancy and having a recess in the underside of the buoyance means defining a cavity with means for supplying or evacuating air from the cavity when the buoyance means is submerged. The buoyance means is preferably formed of concrete. The top wall of the cylinder is preferably arranged movable in the axial direction inside the cylinder, and exhibits means for locking or releasing the top wall at desired elevation inside the cylinder.

The cylinder does advantageously exhibit a number of additional inlet valves distributed at a mutual distance in the height direction, and a number of additional outlet valves mutually distributed at a distance in the height direction. The inlet valve is preferably a non-return valve preventing seawater to flow out from the lower compartment in the cylinder, and the outlet valve is preferably a non-return valve which prevents seawater from flowing into the lower compartment of the cylinder.

Detailed description

In the following, the invention is described in further details by means of drawings, where: Fig. 1 shows a vertical cross-section through a seawater pump in accordance with the invention,

Fig. 2 shows a side view of the seawater pump in accordance with the invention,

Fig. 3 shows a cross-section through the seawater pump in accordance with the invention in operation during falling tide, and

Fig. 4 is a drawing similar to Fig. 3, in operation at rising tide. Now referring to Fig. 1, a tidal-driven seawater pump is shown, denoted generally by reference numeral 100. The seawater pump comprises a buoyance means 101 connected to a piston 102 through a rigid substantially vertically extending connector means 103, e.g. in the form of a strut or pipe. The piston 102 is accommodated slidably in a cylinder 108 and is located in a sealed manner adjacent to the cylinder wall by a seal 113. The cylinder 108 is in the upper end delimited by a top wall 112 and is at the lower end delimited by a socket 111. The socket is arranged to be located on the seabed and is typically a concrete socket or concrete plate. The connector means 103 is guided through the top wall 112 and is sealed by means of a stuffing box 111. The cylinder 108 does in this way form a lower compartment 109. An inlet manifold 104 is arranged to supply seawater to the lower compartment 109 in the cylinder 108, and exhibits an upper inlet valve 106A arranged at upper part of the lower compartment 109, and a lower inlet valve 106B arranged in the wall of the cylinder 108 at lower part of the same at the socket 111. The valves 106A and 106B are non-return valves preventing seawater from flowing back from the lower compartment 109 to the surrounding sea. Moreover, the seawater pump is provided with an outlet manifold 105 having an upper outlet valve 107A arranged in upper part of the lower compartment 109 and a lower outlet valve 107B arranged in the wall of the cylinder 108 at lower part of the same at the socket 111, corresponding to the inlet valves. The outlet manifold is connected by a conduit in flow connection with a reception onshore or at the sea surface.

Fig. 2 illustrates the tidal-driven seawater pump 100 in a side-view, wherein the piston 102, top wall 112 with stuffing box 111, and the buoyance means 101 are indicated by dotted lines. Moreover, a recess 114 is provided in the underside of the buoyance means 101, defining a cavity in the underside which in a controllable manner can be provided with air to control the buoyancy of the buoyance means 101. A water surface within the recess 114 is indicated by reference numeral 116 in the recess 114.

Still referring to Fig. 2, the buoyance means 101 is accommodated slidably in a protective housing 110 provided with numerous flow apertures, slots or similar 115 and having an open top 110A. The apertures 115 allow seawater in the upper compartment 117 between the buoyance means 101 and top wall 112 to flow out to the surrounding sea during falling tide, wherein the buoyance means 101 floating in the sea surface moves downward together with the descending water surface 118 in the sea surface. In a similar manner, the apertures 115 allow seawater to flow from surrounding sea and into the upper compartment 117 in the buoyance means since an underpressure is created by the buoyance means 101 moving in direction upward during rising tide. This arrangement has the advantage that the tidal-driven seawater pump 100 can be placed even in areas with a lot of waves and is only affected by tidal water and not by waves.

Fig. 3 shows the tidal-driven seawater pump in accordance with the invention during operation during falling tide. The arrow at the connector means 103 shows the direction of movement of the buoyance means 101 and the piston 102 in direction downwards. Seawater flows into upper inlet valve 106A into the lower compartment 109 and out through lower outlet valve 107B to manifold 105 and further to a reception (not illustrated) onshore or at the sea surface.

Fig. 4 shows the tidal-driven seawater pump in accordance with the invention during operation at rising tide. The arrow at the connector means 103 shows the direction of movement of the buoyance means 101 and the piston 102 in direction upwards. Seawater flow into lower inlet valve 106B into the lower compartment 109 and out through upper outlet valve 107A to manifold 105 and further to a not illustrated reception onshore or at the sea surface.

Still with reference to Fig. 4, additional outlet valves are indicated by dotted lines with reference numerals 107 A' and 107 A" and additional inlet valves 106A' and 106A". Moreover, the top wall 112 is adjustable in the height direction (not illustrated). These additional outlet valves and inlet valves combined with the height-adjustable top wall enables control of the volume of the lower compartment between the socket 111 and top wall 112, thus by simple means adapting the tidal- driven seawater pump to different tide differences.

The cylinder 108 does preferably have a low relation H/D, between height H and diameter D, typically from about 2/1 to 1/1. However, the buoyance means 101 with its recess 114 must be dimensioned in accordance with the relation H/D. A low H/D provides high pumping capacity.

Whereas the invention has been described with an inlet manifold 104 and an outlet manifold 105, this is not to be interpreted as obligatory. The respective valves 106A and 106B, and 107A and 107B can operate independently from each other with respect to flow.