Movable underwater pump for wave-actuated desalination with sliding positioning anchor

Abstract

The present invention relates to an underwater pumping device and method capable of moving over the seabed and of converting wave energy into high-pressure seawater pumping action for reverse osmosis desalination. The invention makes it possible to transform wave motion into linear motion by means of surface floats and an underwater float oscillating with the waves. The floats drive pistons that draw in, filter, and compress seawater. The movable pumping device is capable of positioning itself in synchronisation with the period and celerity of the waves by sliding by means of an anchoring system rolling on a conveying pipeline that carries the pumped water directly to a reverse osmosis station. The pipeline is anchored to the seabed by means of a series of deadman anchors. The sliding mechanism makes it possible to retrieve and remove the pumping device from the water for weather-risk prevention and for cleaning and maintenance.

Description

[0001] Description of the invention

[0002] Title of the invention: Wave-powered mobile underwater desalination pump with sliding positioning anchor

[0003] General description

[0004] The present invention relates more particularly to a device for high-pressure seawater pumping. The mechanism is characterized by a piston pump capable of sliding along the seabed, which combines the suction and compression actions of a fluid such as seawater. The underwater pump consists of a set of floats connected in a loop, each with a different volume: a hydrodynamically shaped surface float that captures the wave motion, and two underwater floats that act as tensioning and regenerative devices for the pistons. The two floats are connected to the pump pistons via a free-swinging pulley. The surface float has a larger volume than the two underwater floats combined, and therefore its reaction to waves is greater than that of the underwater floats.The floats and piston are connected by two sliding cables that run through a series of free-swimming pulleys attached to the pump body. The pump contains a twin-cylinder mechanism housing the pistons. The pistons draw in and compress seawater. Compression is achieved by transferring the force generated by the waves on the surface float to the underwater pump located on the seabed. This energy transfer is accomplished by a set of cables attached at one end to the two hydrodynamic faces of the surface float and at the other end to the pistons, which are themselves attached to the underwater recovery float. These cables slide within the pump mechanism, actuating the pistons alternately or in parallel using wave force. In this configuration, the cables act as anchor lines for the surface float.The cable slides within the underwater pump via a free-swinging pulley towards the underwater float, which is attached to the pump piston. This float exerts a constant underwater buoyant force on the piston. In this configuration, we have a series of floats with different buoyancy in different environments. The surface float oscillates with the waves, causing the underwater float to move in the opposite direction. Being in a constant aquatic environment, the underwater float attached to the piston exerts a constant force that keeps the underwater cable taut regardless of the piston's position within the cylinder. In this configuration, the pumping device acts as an anchor point to the seabed.The surface float pulls the cable, which exerts a compressive force on the hydraulic cylinder. This compression is equal to the buoyant force generated by the volume of the surface float minus the volume of the second underwater float attached to the piston. This configuration allows the free pulley to reverse the pulling motion of the surface float towards the float connected to the piston. The upward movement of the surface float is transformed into a downward pulling motion, thus pulling the underwater float downwards. The cable exerts a downward compressive force on an external rod attached to the piston via the free pulley, while the float is pulled upwards by the waves. The piston is fixed at its upper end to an underwater float; this float is attached to the piston and maintains constant tension on the cable.This arrangement allows the piston to rise in the cylinder due to the buoyant force exerted by the underwater float. This action draws seawater into the cylinder through a self-supporting filter. The energy required to fill the cylinder with seawater is solely due to the underwater float (tensioner). This combination allows for three distinct actions: maintaining the cable connecting the float to the pump under tension, allowing the cylinder to fill by drawing seawater into it, and automatically adjusting the tension of the traction cable to the tide height. The length of the cylinder represents the maximum range of motion within which the float can move according to the swell and the tide.The piston is attached to a bored rod that slides tightly within the cylinder. The rod is fixed to the traction cable and aligned with the free pulley. In this configuration, the piston rod maintains perfect linearity, preventing it from twisting under lateral forces. The pumped water is recirculated through manifold blocks containing pipeline inlet valves. Each manifold block is fixed to a deadweight by means of mounting arms. The piston block is attached to a sliding block on a pipeline via a universal joint, allowing the piston block some freedom of movement relative to the sliding block. Because the piston block is massive, it tends to sag laterally due to a lack of buoyancy; therefore, lateral float blocks are attached to the piston block to provide slightly positive buoyancy.The sliding block connects the pump valve to the pipeline valves, directing the pressurized pumped water to the shore. The pipeline is anchored to the seabed, fixed to a series of concrete blocks acting as moorings. In this configuration, the pumping system consists of a seawater pumping and compression unit and a sliding unit connected by a universal joint and a flexible hose. The sliding block moves along the pipeline on convex rollers that conform to its cylindrical shape. This configuration allows the sliding block to remain firmly held in a vertical plane to resist the vertical thrust of the floats while remaining mobile in a horizontal plane. The sliding unit includes a telescopic quick-connect valve for easy connection to the pipeline.

[0005] The pump is moved using a tug that slides along a rack rail fixed parallel to the pipeline and anchored to the same deadweights. The rack rail itself contains a series of teeth that allow the underwater tug to move. The tug is motorized, either autonomous or remotely controlled, and slides along the rack rail.

[0006] The subsea tug includes a telescopic arm that attaches to the pump via a guide cone, actuates the telescopic quick-connect valve that links the mobile pump to the pipeline, and serves as a towing point. The arm retracts as the tug moves along the rack rail; once aligned with the pump's sliding block, the arm telescopes and engages with the guide cone. The tug also includes guide rollers that allow it to slide linearly while maintaining resistance to vertical forces. The flexible pipeline includes a series of ports: a debris removal port located downstream, a connection port to the desalination plant for pressurized water supply located upstream, a port connected to a bladder to stabilize the flow within the plant, and a lateral port for cleaning and internal pipeline maintenance.The handling port allows the insertion of a cleaning and inspection device the size of the pipeline's internal cross-section. This device moves within the pipeline from the upstream port to the downstream port, scraping and pushing away debris and other impurities. History of the reinvention.

[0007] The present invention belongs to the family of wave energy capture devices for high-pressure pumping of seawater for desalination by reverse osmosis. Given that our planet is undergoing advanced warming, the supply of fresh water has become an existential question for humankind. The depletion of freshwater sources such as lakes and aquifers has led the international community to focus on research and development of technologies and to develop processes and mechanisms for recovering or generating fresh water in various ways. One of the technologies that represents the greatest potential in the short and medium term, and also the most widespread in recent years, is seawater desalination by the reverse osmosis process.Although several desalination technologies exist, such as staged distillation or retectrodialysis, reverse osmosis technology represents a true revolution since the advent of osmotic membranes in the 1960s and their industrialization in the 1980s. These membranes, with their mesh structure, allow the H2O molecule to pass through while blocking other particles, particularly salt. That said, the reverse osmosis desalination process requires specific operating conditions. The first is high water quality; it must be free of particles, microorganisms, and sand to preserve the polyurethane membranes. This requires pre-filtering the pumped water. The second is high water pressure at the inlet of the membrane tubes. This pressure varies between 50 and 80 bar.Such pressure, combined with a water flow sufficient to supply habitable areas, requires considerable high-pressure pumping energy. In a standard reverse osmosis seawater desalination plant, approximately 2 kWh per cubic meter is needed. The question of energy availability then becomes crucial, compounded by the importance of reducing reliance on fossil fuels as much as possible. It is therefore essential to adapt green and renewable energy technologies to the reverse osmosis desalination process. Desalination plants currently exist that operate using solar or wind power; in both cases, the goal is to generate electricity to power the multi-stage centrifugal pumps required for pumping and compressing the seawater.In terms of efficiency, the step of converting solar or wind energy into electricity to power the pumps represents a major loss of performance. In our case, wave and swell energy is an alternative to solar and wind power due to its consistency, predictability, and especially its density. That said, despite the advantages of wave energy over the most widespread renewable energies, the wave energy technologies available on the market, while varied and efficient in some cases, have not yet allowed this technology to reach sufficient maturity for large-scale use. Many wave energy projects are isolated, consisting of small, mostly experimental units.The difficulty in implementing this marine energy capture process lies primarily in the nature of the extraction environment. The marine environment is extremely abrasive due to sand suspended in the water, corrosive due to salt and ions, and subject to high mechanical stresses from constant swells. Furthermore, the marine environment contains a multitude of living organisms, both microscopic (bacteria, fungi) and macroscopic (algae, barnacles), which colonize any submerged object, affecting its hydrodynamics and moving mechanical parts. This series of constraints represents a major design challenge, as well as a challenge in the deployment and on-site implementation of these very expensive technologies. Maintaining the various devices in the marine environment presents a significant challenge for these technologies, far more so than the mechanical efficiency of the capture devices themselves.The material and human intervention costs in marine areas are high due to their safety standards and the scarcity of equipment and resources authorized for this type of intervention. Since wave energy is renewable and readily available, its profitability lies solely in the operating cost. Several patents address the subject of seawater pressurization using wave energy, notably patents WO 2017 / 21088A1, WO 2009 / 055884 AI (published May 7, 2009), WO 2014 / 100674 AI (published June 26, 2014), and CN103214063B. Having listed the various constraints and issues that impact the cost of these systems, making them more expensive than the device itself and less profitable in terms of cost per kWh, the remaining factors are significant. Our answer to this problem lies in a device and a process capable of pumping seawater at high pressure using wave energy.The device supplies pre-filtered seawater to a reverse osmosis desalination plant. The invention also addresses the issue of the device's resistance to seawater by enabling automated movement of the pump along the seabed for optimal positioning in the face of swells, and a process for automatically returning the pumps to the breakwater for maintenance and protection against heavy swells and storms. Detailed description of the invention.

[0008] A device and method for a submersible pump sliding on the seabed, comprising a submersible pump (1) containing a surface float (2) composed of two hydrodynamic faces (21) and (22), and a pump body (3) containing two twin pumping mechanisms, left and right, comprising pumping cylinders (4) and (44) containing internal pistons (5) and (55) fixed to piston rods (500) and (500). !The entire assembly is secured to recovery tensioning floats (6) and (66). The float, piston, and piston rod assembly is connected by two cables (7) and (77), respectively attached to the surface floats (2) at the hydrodynamic faces (21) for cable (7) and (22) for cable (77). These cables pass through alignment and guide pulleys (8) and (88) and angle transfer pulleys (90) and (91). The pump body (3) contains lateral floating plates (333) that allow it to maintain positive buoyancy. The pump body (3) is attached to a hinged gimbal (9), which is attached to a rolling frame (10) sliding on a pipeline. The pipeline (11) is towed by a submersible tug (12) using a telescopic arm (98) that connects to the tug via a guide cone (99). The tug (12) moves along a rack rail (112). The pipeline (11) contains regularly spaced quick-connect valves (111) that connect to the submersible pump (1). The pipeline (11) is held submerged by deadweights (13) using height-adjustable mounting arms (131).

[0009] In an improved embodiment of the invention, the surface float (2) of the submersible pump (1) reacts to the swell H. The swell H moving in the direction S3 over an amplitude (maximum) H1; H2 and over a swell period P1; P2 in a general water volume governed by the tidal height (minimum) M1; M2,

[0010] The cylindrical float (2) is positioned to receive the swell head-on at its hydrodynamic faces (21) or (22). Facing the swell in the S3 direction, the surface float (2) reacts at face (21) and, thanks to the Archimedes' principle, is lifted from position H2 to position H1. This displacement represents the movement of part (21) of the float (2) from the trough to the crest of the wave, while face (22) moves in the opposite direction from H1 to H2, from the crest to the trough of the wave. This configuration allows the device to simultaneously actuate pistons (5) and (55) by oscillation, in opposite, alternating, or parallel directions. In all configurations, the displacement vector H is always opposite to the displacement vector D.The displacement from H1 to H2 of the face (21) of the float (2) exerts a force V1 in the vertical direction S1 on the cable (7). The cable is guided from its attachment to the face (21) of the float (2) to the body of the pump (3) through the alignment and guide pulley (8), which allows it to engage correctly in the body of the pump (3). The cable (7) runs the entire length of the body of the pump (3), a length which represents the length of the cylinder added to the length of the piston and its piston rod in its maximum extension D1. The cable (7) moves 180 degrees around the angle transfer pulley (88) and pulls in the vertical direction S2 on the piston (5). The piston compresses the water contained in the cylinder (4). Under the action v1, the piston (5) moves in the cylinder in an amplitude (max-min) D1; D2 which is equal to H1 and H2.The suction of seawater into the cylinder (4) is done by means of the force generated by the Archimedes' thrust of the recovery float (6) fixed to the piston (5) which rises in the direction S2 while the surface float (2) in its face (21) is in downward movement S1 the admission of seawater into the cylinder (4) is done by the inlet valves (51) the seawater is filtered by a self-cleaning rotating primary inlet filter (52) by means of the centrifugal force which expels the particles fixed on the grids (522) of the filter.The rotary primary filter (52) is actuated by the movable rack rod (53) which moves vertically on the gear (522) itself actuated in an upward manner by means of the Archimedes' thrust by its attachment to the float (5) and downward by gravity by means of the hydrodynamic mass (523) respectively in an alternating or parallel manner the aspiration of seawater into the left cylinder (44) is done by means of the force generated by the Archimedes' thrust of the recovery float (66) attached to the piston (55) which rises in the direction S2 while the surface float (2) in its face (22) is in downward movement S1 the admission of seawater into the cylinder (44) is done by the inlet valves (5) the seawater is filtered by a rotary primary inlet filter (52').

[0011] After its alternating or simultaneous admission into the cylinders (4) and (44), the pre-filtered seawater is forced into the orifice of the non-return valves (53) and (53 !) through the filters (533) and (533') by the movement of the pistons (5) and (55) from levels DI to D2.

[0012] Upon reaching the end of the stroke from position D2' to D2, the remaining seawater in the cylinder sections is laden with particles. The accumulated microparticles are retained in the cylinders by the filters (533). They are discharged via an expulsion channel (501) through the discharge ports 01 and 02 located on the piston rod (500). Rotating blade scrapers (502), driven by a helical guide screw (503) actuated during the stroke from D2' to D2, scrape and clean the filter (533) and expel the particle-laden sludge under high pressure through the expulsion channel (501). The seawater, filtered a second time at the outlet of the non-return valve (53), is conveyed through rigid conduits (101) fixed to the pump body (3) to the manifold (122). A flexible conduit (132) capable of oscillating with the cardan joint (9) allows for a flexible connection with the quick connector (102) fixed to the sliding chassis (10).The quick connector (102) connects to the quick connector (111) and supplies the pipeline (11) with pressurized seawater. The quick valves are connected, and the marine pump (1) is pulled by means of the telescopic arm (88) attached to the underwater tractor (12), which clips onto the guide ball joint (99) fixed to the sliding frame (10). The movement of the underwater pump (1) along the pipeline is achieved by motorized sliding on the rack rail (112) of the tug (10). The tug contains an electric traction motor that grips the rack rail (112). The motor (55) is controlled and electrically powered by the self-floating umbilical (606), which is kept in positive buoyancy by means of the floats (607). The self-floating cable (606) is guided on the rack rail (112) by means of the cable guides (608).In an improved application of the method, the tugboat (10) allows one or more pumps (1) to be moved along the rail (11), and connected to and disconnected from the pipeline (11). The semi-rigidity of the pipe (11) provides it with a degree of flexibility, enabling it to be moved up a dike (1121). By this method, the tugboat can bring all the pumps (1) sliding along the pipeline and the surface floats (2) back onto the dike (1121). In an improved use of the invention, the pumps (1) and the floats (2) are stored on the dike using the handling crane (1117). The pipeline is flexible. includes a debris discharge port (1111) located downstream, a connection port (1112) to the desalination plant for pressurized water supply located upstream, a port (1113) connected to a bladder (1115) for flow stabilization located in the desalination plant, and a lateral port (1114) for internal cleaning and handling of the pipeline (11). The handling port (1114) allows the introduction of a cleaning and inspection device (1116) the size of the internal cross-section of the pipeline (11), which moves within the pipeline from the upstream port in position E1 to the downstream port in position E2, scraping and pushing away particles, algae, and residues in order to discharge them through the port (1111).

[0013] Image description

[0014] Other features and advantages will become clearer from the following description, which is purely illustrative and not exhaustive and should be read in conjunction with the attached figures, including:

[0015] Figure 1: Schematic representation of a perspective of the device.

[0016] Figure 2: Schematic representations of a perspective of the device deployment process.

[0017] Figure 3: Schematic representations of the pipeline and dead bodies. Figure 4: Schematic representation of a cross-section of the device.

[0018] Figure 5: Schematic representation of a cross-section of the device.

[0019] Figure 6: Schematic representations of a perspective of the device.

[0020] Figure 7A and 7B: Schematic representations.

[0021] Figure 8: Schematic representations of a cross-section. Figures 9A and 9B: Schematic representations.

Claims

AMENDED CLAIMS received by the International Bureau on February 4, 2025 (04.02.2025) Demands Claim 1: A subsea device intended for use with a flexible subsea pipeline, comprising: • a trolley (10) equipped with rollers (97) which ensure sliding on the pipeline (11), the rollers conforming to the shape of the pipeline (11) • an articulated cardan joint (9) which fixes and orients an underwater pump (1) on the trolley (10) • Surface floats (2) located on the water's surface, designed to capture the force of the swell and power the pump through their movement • a series of mooring blocks (13) which hold the pipeline (11) to the seabed each mooring block being connected to the pipeline by a fixing arm (131) one side of the arm being integral with the mooring block and the other side being fixed to a junction section of the pipeline (11) • a quick-connect valve (111) located on the pipe (11) which allows the pump (1) to connect in a watertight manner and inject pressurized water into the pipe (11) • a rack rail (112) arranged parallel to the pipeline (11) which is used by a motorized underwater tug (12) to move parallel to the pipeline and connect the sliding devices to the connecting valves (111) located on the pipeline (11) using a telescopic arm (98) Characterized in that the sliding devices include a wave-driven underwater pump (1) and a series of connections for transferring pressurized water into the pipeline (11). Claim 2: Device according to claim 1 characterized in that several trolleys (10) and pumps (1) are installed at intervals corresponding to the period of the swell which allows each float (2) to capture the energy of the waves and generate continuous and synchronized pumping. Claim 3: Device according to claim 1 characterized in that the floats (2) are arranged so as to exploit the vertical movement of the swell activating the submerged pumps (1) and ensuring the injection of pressurized water into the pipeline (11) at optimal times depending on the period of the swell. Claim 4: Device according to claim 1 characterized in that the self-floating umbilical (606) consists of submerged floats (607) which keep the cable on the surface of the water ensuring a continuous supply of power and communication between the tug (12) and the rest of the device. Claim 5: Device according to claim 1 characterized in that the underwater pipeline (11) and the rack rail (112) are fixed to the seabed by means of fixing arms (131) common to the moorings (13) thus forming a stable and parallel assembly which allows the motorized underwater tug (12) to move along the rack rail (112) with precision and which ensures the efficient connection between the telescopic arm (98) and the guide ball (99) of the trolley (10) thus facilitating the connection with the valve (111) of the pipeline (11). Claim 6: Device according to claim 1 characterized in that the motorized underwater tug (12) is electrically powered by a self-floating umbilical (606) comprising several submerged floats (607) distributed over the entire length of the cable, thus allowing the cable to move freely while being guided on the rack rail (112) by slides (608) and to stretch or retract depending on the distance between the tug (12) and the shore. Claim 7: Device according to claim 1 characterized in that the self-floating cable (606) is guided on the rack rail (112) by slides (608) fixed at regular intervals on the cable these slides ensuring the tracking of the movement of the tug (12) thus maintaining a constant tension and a stable trajectory while ensuring optimal cable management according to the position of the tug. Claim 8: Device according to claim 1 characterized in that the telescopic arm (98) of the underwater tug (12) allows the trolley (10) containing the pump (1) to be fixed and moved along the pipe (11) and to mechanically introduce the pump into the connection valve (111) of the pipe (11) ensuring the tight connection between the pump (1) and the pipe (11) by means of tenons (88) which fit into the lateral openings of the conical receiver of the guide ball joint (99) of the carriage (10). Claim 9: Device according to claim 1 characterized in that several sliding devices are installed on the same pipeline (11) each device being designed to be operated independently of the others which allows parallel or sequential operation of several pumps (1) on the same pipeline as required. Claim 10: Device according to claim 1 characterized in that the subsea tug (12) and trolley (10) are designed to operate manually and autonomously by means of operators or integrated electrical and mechanical systems allowing each device to move and make connections autonomously along the pipeline (11) and allowing adjustment and connection of the sliding devices to each connecting valve (111) as required.

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