Systems and methods for desalination of water

Abstract

A system for producing desalinated water from seawater or other salt water, comprising the following equipment arrangements or items of equipment in the direction of flow: a subsea seawater inlet and a subsea pre-treatment stage including at least one or more of a subsea filter and / or a subsea seawater pre-treatment unit and / or a subsea coarse screen unit and / or a hydrocyclone, and a subsea feed pump, the subsea feed pump being fluidly connected to a subsea RO unit, a subsea production pump being fluidly connected to the RO unit production outlet, a production line being fluidly connected to the subsea production pump and a subsea feed pump being fluidly connected to the RO unit waste outlet, which is preferably connected to a waste line. The system is characterized in that the subsea seawater inlet is at a depth below or within the thermocline of seawater, i.e. below the surface water layer or as close as practicable if the local depth is insufficient to reach the thermocline, and the system is preferably without any barrier fluid supply to the subsea pump.

Description

Technical Field

[0001] The present invention relates to the production of demineralized water or purified water or fresh water, that is, water with a salt content of less than 0.3%. Such water is produced from salt water, that is, water with a salt content of 3 to 5%, typically from water in the salt sea, ocean, or fjord or bay, or from brackish water, that is, water with a salt content of 0.3% to a maximum of 3%, or alternatively from contaminated water. The present invention relates to a system or plant for such production, a method for installation, and the operation and / or maintenance inspection of the system of the present invention.

Background Art

[0002] Fresh water is a limited resource and can be a major source of contention. In the United Nations Sustainable Development Goal 6, it is explicitly stated that "Water is at the heart of the 2030 Agenda for Sustainable Development. Water underpins our lives, our health, our environment, and our economies. Managing water sustainably is an investment in the future not only of the current generation but of all generations to come. This aim is essential to ensure the availability and sustainable management of water and sanitation for all people and to shift the world onto a resilient path that leaves no one behind."

[0003] Less than 1% of all water is fresh water readily available from surface or underground water sources, and approximately 70% of that is used in agriculture. In contrast, approximately 97% of all water is salt water.

[0004] Desalination is the process of reducing the content of dissolved salts in salt water or brackish water. In recent decades, reverse osmosis has become the most suitable method for desalination mainly due to significant cost reduction resulting from the introduction of more effective reverse osmosis membranes and more effective energy recovery.

[0005] Reverse osmosis is the diffusion of water molecules from the salt side of a reverse osmosis membrane to the semipermeable membrane, the side with a lower salt concentration, achieved by pressurizing the fluid on the salt side to a pressure exceeding the osmotic pressure head. The semipermeable membrane allows water molecules to pass through and diffuse, but not larger molecules or ions that aggregate or have other characteristics that prevent them from diffusing through the semipermeable membrane. The basic design of a reverse osmosis membrane is described and illustrated in U.S. Patent Publication No. 4277344. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Patent Publication No. 4277344 [Non-patent literature]

[0007] [Non-Patent Document 1] Published December 30, 2011, Journal of Geophysical Research, Vol. 116, "Production and fate of transparent exopolymer particles in the ocean." [Non-Patent Document 2] https: / / www.nature.com / scitable / knowledge / library / the-biological-productivity-of-the-ocean-70631104 / [Non-Patent Document 3] https: / / www.sciencedirect.com / topics / chemistry / osmotic-pressure [Overview of the project] [Problems that the invention aims to solve]

[0008] Despite years of comprehensive efforts and improvements, there is still a demand for improved systems and methods for the production of fresh water by reverse osmosis, as well as for methods of operating and using reverse osmosis products. Challenges involving water intake, corrosion, high power consumption, large area requirements, high operating and maintenance costs, high labor requirements, and a lack of operational stability are some of the areas where improvement is possible. The object of the present invention is to satisfy this demand by providing a structure, method, and / or use that has a positive effect on one or more of these areas where improvement is possible. [Means for solving the problem]

[0009] The present invention relates to a system for producing desalinated water from seawater or other brine, and in a typical flow direction, the following equipment mechanism or equipment items: Underwater seawater inlet, An underwater pretreatment stage comprising at least one or more of the following: an underwater filter and / or an underwater seawater pretreatment unit and / or an underwater coarse screen unit and / or a hydrocyclone, It is an underwater water supply pump, Underwater RO unit, A submersible production pump fluidly coupled to the RO unit's production outlet. A production line fluid-coupled to an underwater production pump, and Preferably, the RO unit waste outlet is connected to the waste line. A submersible water supply pump that is fluidly coupled to it We provide a system that includes the following features.

[0010] The system is The underwater inlet is located below or within the thermocline of the seawater, that is, below the surface layer, or as close as possible if the local depth is insufficient to reach the thermocline. The system preferably does not involve any barrier fluid supply to the submersible pump. This is its distinguishing feature.

[0011] Preferably, the system is The system comprises one or more underwater treatment pods located below or within the thermocline of seawater, i.e., below the surface seawater layer, or as close as feasible if the local depth is insufficient to reach the thermocline. The underwater processing pod includes equipment items selected from at least the equipment items or equipment mechanisms defined above and arranged in an operational manner. The processing pod is recoverable.

[0012] Preferably, the system does not involve any external barrier fluid supply to the submerged pump, and the pump simply requires the process train fluid to enter, process train fluid to exit, and power and control to be operational. Therefore, in addition to the incoming and outgoing process train fluid (pre-treated seawater, or permeate / freshwater, which is the product), the coupling required for the operational pump consists of power and control, and barrier fluid supply is not required, even if it is not a production pump. This significantly reduces the overall system requirements and infrastructure and greatly simplifies the required operation. Furthermore, contamination of the product from the pump and the produced freshwater is eliminated.

[0013] In this context, a processing pod refers to a frame structure, cage structure, or support structure that supports one or more equipment items of a system, and the entire processing pod is recoverable in a single operation. Typically, the multiple equipment items placed on the processing pod are recoverable in a single operation and can be installed in a single operation. Typically, one or two flowline coupling components are included, one of which is for power or a combination of power and control for each processing pod. The coupling components are preferably remotely operable by a coupling operation during installation and / or by an ROV (Remotely Operable Vehicle) or ROT (Remotely Operable Tool). The processing pod may include recoverable and therefore individually replaceable equipment items. Each processing pod is placed on a more permanent foundation base on the seabed.

[0014] The system preferably comprises a processing pod with recoverable equipment mechanisms operably positioned on the processing pod. Preferably, at least the pre-processing unit equipment is recoverable without recovering the entire processing pod. Preferably, all equipment mechanisms that do not face high pressure, up to the inlet to the submarine production pump, may be recoverable in some embodiments. However, even in many embodiments, the submarine production pump is recoverable.

[0015] The system preferably includes submersible fluid connectors, which are clamped or not clamped submersible flowline connectors for horizontally and / or vertically oriented flowline or pipe portions, such as submersible hose connectors, at least one of the arrangements of the ends of each processing pod downstream of the processing pod or the submersible inlet. Commercial suppliers of submersible flowline connectors include DESTEC, Oilstates, Baker Hughes, Oceaneering, and OneSubsea.

[0016] The system preferably comprises a light work-class ROV-operable underwater connector for joining and separating flow line joints, preferably by a light work-class ROV. The light work-class ROV, a remotely operated vehicle, is an ROV class that lies between an observation-class ROV and a heavy work-class ROV. The light work-class ROV preferably comprises at least one manipulator function for valve operation and / or torque tool operation in addition to a camera function, for example, a manipulator arm that can bend at least ±90° to open or close a clamp connector.

[0017] Preferably, all manipulation-operable operations for the light work-class ROV are performed only from one or two sides of the processing pod of the system of the present invention. Preferably, a docking structure for eliminating reaction force and facilitating the operation of the light work-class ROV is provided on the processing pod. The light work-class ROV available from most ROV providers can be deployed from a light seagoing vessel without a heavy cage around the ROV, enabling a lighter intervention vessel or seagoing vessel to undertake the operation. When the ROV is pushed forward with complementary-shaped structures abutting within the docking structure, the reaction force is eliminated and the positioning of the structure to be operated by the ROV on the processing pod is fixed. The system preferably comprises a control panel, which is accompanied by an integrated docking structure for an ROV such as a light work-class ROV, and preferably includes a control device for most or all of the underwater operation tasks operable by the light work-class ROV, including connection and disconnection of equipment items from the processing pod and / or the underwater processing pod.

[0018] The system preferably has a stub in the junction between the pre-filter unit equipment mechanism and the processing pod. The stub in the junction is a connection that does not require rotation for joining. The stub in the connection is balanced, that is, the flow port directions of the male and female parts are oriented 90° apart, and thus preferably eliminates reaction forces. The stub in the junction is preferably a junction of one or two holes with inlet and outlet flow holes.

[0019] The system preferably has a processing pod frame over some or all of the processing pods, which is a structure for lifting the processing pods for recovery and installation, a structure for protecting the equipment mechanism from impact through the splash zone during deployment and recovery, and also a troll protection and fishing net protection when on the seabed.

[0020] The frame and / or processing pod preferably include tanks for ballasting and de-ballasting, which are arranged at higher locations of the frame and / or processing pod, preferably for hydrodynamic stability, to facilitate installation and recovery.

[0021] The system preferably has a transponder or similar device for positioning, which is arranged on the guide post, guide post ventilation duct, coupling parts, and / or other equipment items. The system also preferably has a camera and lighting on the equipment items and / or processing pod, which are coupled to the control system and can be monitored and controlled from the control room of a ship or other location for installation and / or maintenance inspection. Thereby, installation and recovery are facilitated.

[0022] The present invention also provides a method for the installation, operation, and / or maintenance inspection of the system of the present invention. The method has, in any combination, the following features: The step of towing the processing pod to a location on water or transporting it by other means, A step of installing a processing pod with an air-filled or vacuum ballast tank, thereby continuously emptying the ballast tank until negative buoyancy reaches a suitable level, and thereafter deploying the processing pod to a location, preferably using a transponder and / or camera for positioning control, and installing the processing pod with foam buoyancy elements such as syntactic foam buoyancy elements. The process involves using one or more ROV-free connections that can be joined by a light work-class ROV when connecting the processing pod to a more permanent structure on the seabed, The process involves using one or more ROV-free joints that can be joined by a light work-class ROV when detaching the processing pod from a more permanent structure on the seabed, When installing or retrieving pre-processing unit equipment items, the steps involve using ROV-free coupling or uncoupling. It comprises one or more of the following.

[0023] This method, During operation for reverse osmosis, the feed pump is used at a lower differential pressure than normal operation, typically 0.7 to 1 bar (70 kPa to 100 kPa), and preferably, on the other hand, the differential pressure is periodically increased, typically to 1 to 2 bar (100 kPa to 200 kPa), thereby leading the waste with significant pressure to the filter backflushing and the hydrocyclone of the pretreatment unit. Steps to operate the system: 15-70% of the maximum recommended recovery rate of the RO unit on land, preferably a lower recovery rate of approximately 20-40% or approximately 30% of the maximum recommended recovery rate. It further includes the following, which may provide operation with increased service or replacement intervals.

[0024] The processing pods of the present invention are most preferably placed at depths below where photosynthesis and mixing with surface water occur. This means depths below or within the thermocline. Seawater below or within the thermocline has a higher salinity and is far more nutrient-rich than the lighter and warmer surface water because there is no photosynthesis that consumes nutrients.

[0025] To our great surprise, by placing many, or most preferably all, of the system's treatment pods below or inside the thermocline, rather than just the seawater inlet, the requirements for pretreatment, the long-term operation of the RO unit, marine product adhesion, and scaling of equipment and treatment pods are significantly reduced.

[0026] To be observed from a location on land or above the sea surface, the system of the present invention preferably comprises a single umbilical for power and control from the surface location and a flow line of product freshwater connecting the underwater component of the system to the component above the sea surface.

[0027] Surprisingly, by having the seawater inlet below or within the thermocline, a reduction of approximately 40–80% or more in pretreatment requirements can be achieved. Surprisingly, placing the treatment pod, along with all equipment items, in the sea at depths below or within the thermocline is advantageous in several respects, including a significant reduction in onshore utility requirements and increased safety.

[0028] However, in some embodiments of the present invention, shallow basins near the coast where the water surface is below the sea surface but filled only by seawater from below or within the thermocline, or filled with produced freshwater, may be alternative locations for some of the equipment items or processing pods.

[0029] A crucial aspect of this invention is the location of the seawater intake, as well as the further equipment and processing pods. At the very least, the seawater intake location should be selected with utmost care, as the technical effect on the entire system depends considerably more on the seawater intake location than might be expected.

[0030] If the thermocline is inaccessible or only its highest portion is reachable, the seawater intake site, and preferably further equipment and processing pods, may be found as described below.

[0031] The location and depth of the seawater inlet are preferably determined by finding that the silt density index (SDI), transparent exopolymer particles (TEP), and / or light intensity at that depth are reduced by 20%, more preferably 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 97%, 98%, or most preferably 99% or more from the surface water reference value, and at least the seawater inlet should be at that depth or deeper below the surface. The method used to measure any one of these parameters must be carried out steadily. The intensity of sunlight can be determined by light intensity measurements using commercially available equipment at depth intervals. The concentration of transparent exopolymer particles (TEPs) can be determined by measuring TEPs spectrophotometrically, as described in scientific papers, e.g., the Journal of Geophysical Research, Vol. 116, published December 30, 2011, “Production and fate of transparent exopolymer particles in the ocean.” TEPs will decrease significantly below where significant agitation and mixing of biomolecules from surface water occur. Thus, measuring TEPs as described above is one of several good indicators for avoiding mixing with surface water. Other indicators include, for example, the concentrations of bacteria and phytoplankton. The silt density index (SDI) of unprocessed, untreated seawater at depth intervals is perhaps the best and most preferred indicator, as it correlates directly with membrane / filter fouling and pretreatment requirements. The SDI of unprocessed, untreated seawater shall be measured at depth intervals according to the standard test method ASTM D4189. For example, unprocessed, untreated seawater samples are collected at depths of 1m, 10m, and 20m, with the highest SDI and / or TEP values ​​used as a baseline, and further unprocessed, untreated seawater samples are collected at greater depths.The depth at which SDI and / or TEP and / or solar intensity and / or mixing with surface water and / or bacteria are reduced by 20%, more preferably 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 97%, 98%, or more than 99% from the reference value is the depth at which the seawater inlet is located.

[0032] In this context, the term “significant” means seawater in which susceptibility to reverse osmosis membrane fouling is reduced by at least 20% in accordance with SDI and / or TEP, or in which solar intensity is reduced by at least 20%, and / or in which mixing and / or bacterial concentration is reduced by at least 20%.

[0033] SDI samples from surface water and the mixed layer do not necessarily need to be taken at depths of, for example, 1 m, 10 m, and 20 m, or 5 and 15 m, or 1, 15, and 30 m. The examples of depths are to ensure that the results for surface water in the mixed layer are representative. Water clarity, wind causing mixing, and other factors can vary, and as a result, the depth or thickness of the mixed layer above the thermocline will vary from about 10 m in very narrow bodies of water to at least about 100 m in the ocean. The thermocline can extend from about 10 m to about 1000 m in the warm waters of the open ocean. More general information on technical terms and seawater conditions can be found, for example, below. https: / / www.nature.com / scitable / knowledge / library / the-biological-productivity-of-the-ocean-70631104 /

[0034] An SDI value of 1 or less is assumed to result in stable operation of the RO unit's RO membrane for many years without colloidal fouling. An SDI value of around 3 may imply cleaning of the RO membrane at intervals of several months. An SDI value in the range of 3 to 5 may imply cleaning at intervals of several months to several weeks. An SDI value greater than 5 requires pretreatment of the water to be desalinated. Below the mixing region, in addition to the essential filter or coarse screen unit, there may be points of very clean water that require no pretreatment or only minimal pretreatment. Near the surface, the SDI can be at most about 200. Since there does not necessarily need to be any clear and strict correlation between a decrease in sunlight intensity or a decrease in particulate matter or suspended solids that cause RO membrane fouling, the most reliable parameter for inlet depth may be the SDI. This is due to the content of other organic and inorganic suspended solids that fluctuate worldwide throughout the year, including uncertain phytoplankton mixing, uncertain zooplankton mixing, their aggregation, and the content of other organic and inorganic suspended solids that cause RO membrane fouling. Studies have shown that transparent extracellular polymer particles (TEPs) can play a significant role in the biofouling of RO membranes. TEPs are highly viscous particles with gel-like characteristics. These gel particles have been shown to be abundant worldwide in seawater, either in particulate form or as dissolved polymer mucus. However, TEP concentrations decrease with depth, decrease with decreasing sunlight, and decrease with decreasing algal blooms. In marine systems, the majority of TEPs are formed abiotically (in a lifeless state) from dissolved precursors released by actively growing or aged phytoplankton. TEPs are also generated during the shedding of cell surface mucosa and the breakdown of colonial matrices. However, for one particular area, an inlet depth selected according to the decrease in sunlight intensity and / or the decrease in the content of one or more specific biological factors relative to the depth parameter can be quite reliable, as the effect on the RO unit becomes predictable and pretreatment requirements can be predicted.In this context, the concentration of extracellular polymeric substances (EPS) produced by microorganisms is synonymous with TEP. SDI may directly correlate to pretreatment requirements, and other possible parameters mentioned for determining sufficient water intake depth, and almost certainly further parameters, may correlate more directly or less directly to pretreatment requirements. It should be noted that pretreatment requirements are not necessarily equivalent to the exact type of pretreatment to be selected, as overly coarse pretreatment steps can destroy cells and result in more TEP. For example, further testing and sampling downstream of each pretreatment step with SDI can determine the appropriate level of detail for the entire pretreatment.

[0035] While we do not wish to be bounded by theory, the lower concentrations of living cells and biomolecules in deeper, nutrient-rich water not only reduce the requirements for water pretreatment but also result in less cell damage from pretreatment. Furthermore, and quite surprisingly, the growth of TEP and its synonym ESP is lower, as cells and bacteria grow and replicate rather than create sticky, gel-like biofouling in nutrient-rich water. When the system is designed and operated as specified, the positive effects of increased feedwater salinity outweigh the negative effects.

[0036] Submersible pumps, at least submersible production pumps, preferably have a magnetic coupling that seals and separates the motor compartment of the submersible pump from the water compartment of the submersible pump. The motor in the motor compartment drives the pump via the motor shaft, on the pump shaft which is not in contact via the magnetic coupling. The water compartment includes bearings consisting of water-lubricated bearings, and the motor compartment includes bearings consisting of bearings lubricated by motor compartment fluid contained within the motor compartment, and a cooling circuit coupled thereto. Any leakage of motor compartment fluid is eliminated, and any requirement for barrier fluid supply to the submersible pump is eliminated. The submersible pump is designed for operation for at least 2, 3, 5, 8, 10 years or more without recovery for maintenance and inspection. Most surprisingly, the submersible pump is operated or controlled through just one or two couplings consisting of power or power and control signals coupled to the submersible pump, eliminating any contamination of the product from the submersible pump. This reduces utility, area, and personnel requirements and improves reliability because there are fewer potential failures. However, while any suitable type of submersible pump may be used, the degree of autonomous operation and / or stability or reliability, the absence of emissions or pollutants, and the resulting long-term cost reductions may not be fully or entirely realized.

[0037] At least the seawater inlet, but preferably the equipment and / or treatment pod as well, is preferably located at a depth of 40m, 60m, 80m, 100m, 150m, 200m, or 300m, below a depth where there is direct solar energy-based (photosynthetic) biological growth, and / or below a depth where waves compel agitation and mixing with biomolecules in the near-surface water, and / or where SDI and / or TEP are reduced in the mixing layer by at least 50%, 70%, 80%, 90%, 95%, 98%, 99%, or 99.5% compared to a typical standard at or near the surface. The system of the present invention preferably has a seawater inlet located in or below the thermocline.

[0038] The system of the present invention allows for a reduction in pretreatment equipment on land or on the upper deck upstream of the reverse osmosis unit compared to a typical land-based system, and estimates indicate that reductions of 20%, 40%, 50%, 70%, 80%, or 90% or more are preferably observed in terms of investment, required area, power consumption with or without CO2 emissions, and required personnel. This is due to the combination of water quality with much lower SDI and / or TEP, which is far more suitable for reverse osmosis, and the effectiveness of seawater pretreatment with a seawater coarse screen unit and / or seawater filtration and / or seawater pretreatment unit.

[0039] The pretreatment unit of this system and the seawater inlet of the present invention are equipped with, at a minimum, a seawater filter or seawater coarse screen unit at the seawater inlet. The opening of the coarse screen unit has a maximum diameter or side length of 100 mm, 75 mm, 50 mm, 25 mm, 10 mm, 5 mm, 2 mm, or 1 mm or less. The coarse screen unit is preferably designed to operate for as long as the seawater pump before recovery or replacement. The coarse screen unit is preferably equipped with a sacrificial anode and / or an autonomous unit for backflushing, vibration and / or cleaning. In some preferred embodiments, the coarse screen unit is replaced or supplemented with a filter which may be down to the millimeter or micron size for filtration. One preferred embodiment is a mm or micron filter cloth made from a polymer, copper, brass, or other suitable material, which is arranged to be pulled across the intake opening from one roller to another when the cloth is soiled, and is preferably driven by a stepper motor powered, for example, by a battery-powered autonomous drive or, for example, by a power supply from a submarine pump. The system and seawater inlet preferably further comprises a submarine seawater pretreatment unit which comprises at least a filtration device, preferably a filtration unit for filtering down to micron size. One or more submarine pretreatment units preferably further comprises at least one injection configuration for deoxygenation and / or disinfection and / or anticoagulation and / or scale prevention, each injection configuration or composite injection configuration preferably coupled by a venturi dosing valve to the outlet or inlet of the submarine pump or further upstream, or at other locations which allow sufficient mixing and residence time before reaching any further filtration units and before reaching the RO unit. The injection unit, driven by gravity and / or an upper deck injection pump, is preferably located as a hole in the power and / or control line or umbilical.

[0040] In some preferred embodiments of this system and the seawater inlet of the present invention, a seawater pretreatment unit is located upstream of the seawater intake line, and / or a further pretreatment unit is located between the seawater intake line and the RO unit. These pretreatment units include at least a filtration device with a filtration unit for filtering down to micron size to remove bacteria, and preferably further a filtration unit for filtering down to nano size to remove viruses as well. Filtration is preferably microfiltration, down to 1 micrometer, thereby eliminating bacteria from the water to be desalinated, and nanofiltration, also called ultrafiltration, is used, down to 1 to 20, 50, or 200 nanometers, thereby eliminating viruses as well. The resulting concentrate is suitable for use in aquaculture (farming fish and shellfish), fertilizer production, mineral production, and / or chemical production, and the produced freshwater is directly suitable for agriculture and, after optional further treatment, is suitable as drinking water and a green hydrogen source.

[0041] In some embodiments, the pretreatment unit includes a filtration unit that can be replaced by a service boat. Embodiments of pretreatment units without an integrated pump may be most preferred because one mechanical connection may be sufficient. If the unit is too large or too heavy to be easily handled by a service boat with a crane / winch and boom, several smaller units in parallel, each small enough to be easily handled, may be preferred. If the stable operating period of the filtration unit is shorter than the period for recovery and maintenance of the submersible pump, an easily replaceable filtration unit may be preferred.

[0042] The power supply is preferably from solar and / or wind sources, and the water supply chain may be zero-emission in terms of CO2 and pollutants. However, conventional power sources may be used. This is especially true if the pump or other components of the system are located on or around an existing platform from which the pump and system can utilize power and other existing infrastructure, in order to reduce costs, improve maintenance capabilities, and accelerate system commissioning.

[0043] The system is listed in typical flow directions in any combination required based on raw, unprocessed inlet seawater quality and production requirements: The disinfection unit upstream of the underwater pump, The sedimentation unit upstream of the pump, An ultrafiltration and / or microfiltration and / or nanofiltration unit upstream of the submersible pump, A submersible pump inlet chamber in which one or more of the units defined above are located, As a biofouling precursor measuring instrument, a chlorophyll fluorescence spectrometer and For example, a biofouling monitoring system connected on-site or remotely for inspecting membrane conditions based on differential pressure and / or flow monitoring, Instruments for measuring dissolved organic matter (DOM) samples and one or more points upstream of the RO membrane, A precision and / or nanofiltration unit located downstream of the water intake line and upstream of the RO unit, RO unit with a reverse osmosis pump and PX energy recovery unit arranged to be operational, At least one tank for freshwater, A tank for the concentrated liquid, A pipe-in-pipe or parallel pipe for discharging concentrated liquid (saltwater), wherein the seawater intake line includes or has concentrated liquid discharge lines arranged in parallel at least a certain distance from the land outlet or above surface level to facilitate pipe laying and surveying, A tank for high-salt solutions (for direct permeation through RO membranes), Configurations for back flash and / or cross flash, Direct penetration for cleaning RO membranes and Preferably, one or more of these, and where necessary or desirable, further comprising piping, valves, optional additional pumps, optional additional units, and fixtures.

[0044] Furthermore, the present invention provides a general use of seawater intake in novel or existing systems or plants for reducing the required degree of pretreatment of seawater or other brine on land or on upper decks, and / or for desalination of brine by reverse osmosis.

[0045] The present invention also envisions the use of multiple pumps and equipment to enable redundancy, increased flow, enhanced filtration, and, in particular, better water quality and performance.

[0046] Furthermore, the present invention provides for the use of the concentrate delivered from the concentrate outlet for aquaculture, fertilizer production, mineral production, and / or chemical production, and / or the freshwater produced is directly suitable for agriculture and (optionally after further treatment) suitable as drinking water and a green hydrogen source.

[0047] Finally, the present invention provides for using a high-salt solution produced by recirculating a concentrated liquid through an RO unit to clean the reverse osmosis membrane of the RO unit by effective direct penetration.

[0048] While the pump for this system is preferably designed and assembled by the applicant, suitable pumps are also available from other commercial suppliers.

[0049] The present invention also relates to the use of the concentrated solution of this system and / or the methods of the present invention, in any combination, free from particles larger than 1 micron, 0.5 micron, 0.1 micron or less, and bacteria and / or viruses: To backflash and / or crossflash the filter, To produce a high-salt fluid for direct penetration to clean RO membranes, Preferably for use in aquaculture, for delivery, to promote the transition of fish from freshwater to saltwater for lower mortality and faster growth, by using a highly pure concentrated solution to grow small salmon into larger salmon and / or to gradually mix with freshwater. To produce industrial products through evaporation and crystallization. The present invention provides the use of a concentrated solution of this system and / or a method of the present invention for one or more of the following. [Brief explanation of the drawing]

[0050] [Figure 1] This figure shows one embodiment of the system of the present invention. [Figure 2] This figure shows how the underwater processing pod of the present invention can be lifted in a single operation. [Figure 3] This figure shows a further embodiment of the system of the present invention. [Figure 4] This figure shows a further embodiment of the system of the present invention. [Figure 5] This figure shows preferred mechanisms of numerous embodiments of the system and method of the present invention. [Figure 6] This figure shows preferred mechanisms of numerous embodiments of the system and method of the present invention. [Modes for carrying out the invention]

[0051] A reference is made to Figure 1, which shows a preferred embodiment of System 1 of the present invention. System 1 of the present invention for producing desalinated water from seawater or other brine or contaminated water comprises, in the direction of flow, an underwater seawater inlet 2, an underwater pretreatment stage 3 including at least one or more of an underwater filter and / or an underwater seawater pretreatment unit and / or an underwater coarse screen unit and / or a hydrocyclone, and an underwater feed pump 4, which is fluid-coupled to an underwater RO unit 5, an underwater production pump 6 fluid-coupled to an RO unit production outlet 7, a production line 8 fluid-coupled to the underwater production pump, and an RO unit waste outlet 9 fluid-coupled to a waste line 10. The underwater seawater inlet is located below or inside the thermocline of seawater at a depth 11 (hydrostatic head), i.e., below the surface seawater layer, or as close as feasible if the local depth is insufficient to reach the thermocline. The umbilical, or more precisely, power and control line 12, is operably coupled to the submersible pump or submersible processing pod for power and control, extends from a location above the seawater surface, and consists of one or two lines or cables without any barrier fluid supply lines to the pump. When operating the system of the present invention, it is sufficient to connect only power and control, which is clearly a unique mechanism that simplifies installation, retrieval, maintenance, and operation while eliminating equipment and infrastructure both underwater and on the shore or upper deck.

[0052] The illustrated equipment items are located inside and on the underwater processing pod 13, and the processing pod is recoverable in a single operation and can be installed or deployed in a single operation. The number of combined operations can be as few as one or two, one combined for power and control and an additional one combined to connect to the production pipeline. Such simplicity is clearly unique.

[0053] The illustrated system embodiment actively utilizes the advantage of natural hydrostatic head at depth to achieve an osmotic pressure difference. In this system embodiment, the seawater feed (seawater) pump only needs to provide sufficient flow to ensure crossflow across the RO membrane and does not need to generate a high differential pressure to overcome the osmotic pressure of seawater. The production pump downstream of the membrane will experience a suction pressure in this system that is lower than the ambient pressure and falls towards or below 1 bar (100 kPa) absolute pressure, but pump cavitation must be avoided. The production pump creates a differential pressure sufficient to bring the flow up to the surface, with sufficient residual pressure for the receiving end, which may be a storage tank or further processing equipment. Here, the production pump downstream of the RO membrane generates the majority of the differential pressure, and since this pump handles only a subset, typically about 50%, preferably less than the total feedwater flow rate (feedwater minus the concentrated liquid to be discarded), the system is also more energy efficient, while minimizing the need for expensive interventions for long-term operation. The inherent osmotic pressure of seawater is 25–33 bar (2.5 MPa–3.3 MPa) (https: / / www.sciencedirect.com / topics / chemistry / osmotic-pressure), and such system embodiments would generally require being located at depths of 300 meters or less, such as 330 m or less, to operate at optimal efficiency. However, the feedwater pump may be configured to deliver a higher differential pressure, as required according to the depth of the location and the requirements for exceeding the osmotic pressure of seawater, which is higher than that of freshwater, on the RO membrane. For example, the differential pressure of the feedwater pump becomes higher as the water depth decreases, in order to ensure sufficient pressure to exceed the osmotic pressure while also avoiding cavitation in the production pump. System embodiments shown in Figure 1 include embodiments ranging from full active use of pressure head at depths of approximately 300 or 330 m or deeper to partial active use of pressure head at depths of approximately 300 to approximately 25 m, with all processing equipment of the complete embodiment remaining located in the sea, preferably at seawater inlet level, as an underwater RO plant.Since the water supply pump does not have a barrier fluid, the downstream membrane is not contaminated with the working fluid, which ensures a longer membrane lifespan and better quality of produced water.

[0054] Figure 2 illustrates how the submarine treatment pod of the present invention can be lifted in a single operation. More specifically, the submarine treatment pod frame also serves as a lifting frame, in addition to protecting the structure and internal equipment from impact through the splash zone during installation and retrieval, and functioning as trawl protection when on the seabed. The coupling operation on the seabed is limited to one or two coupling operations: draining water from the submarine treatment pod and, in some embodiments, filling the submarine treatment pod with water, and one or two coupling operations: power and control.

[0055] The inlet for unprocessed seawater may be located in other places than shown in the illustration, for example, it may be raised higher than the seabed, especially in soft, silty seabed conditions.

[0056] Figure 3 shows the pipeline. Multiple pretreatment-RO treatment pods are coupled to a smaller number of production pumps, which are located on separate or combined treatment pods on a more permanent structure on the seabed called a flow base. A common production flow line leads the production freshwater to a location above the seawater surface.

[0057] Figure 4 shows a further embodiment of the system of the present invention, in which equipment items are arranged as a "row" on a processing pod, with flowline connectors 14 for connecting and disconnecting the equipment items together underwater, oriented horizontally.

[0058] Figures 5 and 6 show preferred mechanisms for numerous embodiments of the system of the present invention. Deballast / deballast allows for simpler and less expensive installation and operation than typical underwater operations. Exhausting air from an integrated tank provides negative buoyancy at a level suitable for installation. Since installation and recovery can account for 20-40% of the capital investment in an underwater project, these mechanisms can reduce the overall cost of installation and recovery. This includes, but is not limited to, avoiding expensive lift-compensated crane vessels. Rather, it uses methods that can be achieved with available workboats, which are common in the Middle East and Mediterranean regions. Installation should ideally be based on surface towing from the shore and ballast / deballast operation using compressed air, or vacuum and / or buoyancy elements, as shown. Larger vessels may be used for capital investment (installation) if necessary, but are preferably avoided due to operating costs (maintenance and inspection). Since seabed structures will vary depending on local soil conditions and other factors, the requirements for mudmats, slabs, skirts, suction anchors, grout, or similar structures must be clearly stated in all cases. Furthermore, pretreatment requirements will vary depending on water quality, expected lifespan, etc., and must be determined on a case-by-case basis.

Claims

1. A system for producing desalinated water from seawater or other brine, in the typical flow direction from seawater or other brine to desalinated water, the following equipment mechanisms or equipment items: Underwater seawater inlet, An underwater pretreatment stage comprising at least one or more of the following: an underwater filter and / or an underwater seawater pretreatment unit and / or an underwater coarse screen unit and / or a hydrocyclone, It is an underwater water supply pump, Underwater RO unit, The underwater production pump is connected to the RO unit's production outlet. The production pipeline connected to the aforementioned underwater production pump, and RO unit waste outlet The underwater water supply pump is connected to the underwater water supply pump. Equipped with, The system comprises one or more submersible pods, each of which is equipped with an operablely positioned equipment item selected from the equipment mechanism or equipment item, and each of the one or more submersible pods and the equipment item positioned in each of the one or more submersible pods is recoverable from the seabed in one recovery operation and can be installed on the seabed in one installation operation, and each submersible pod is equipped with a frame structure for recovery and installation, and for protecting the equipment from impact through the near-surface spray zone during deployment and recovery, A system characterized in that the underwater inlet and some or all of the underwater pods are operably positioned at a depth below or inside the thermocline of the seawater, or, if the local depth is insufficient to reach the thermocline, are positioned as close as feasible.

2. The system according to claim 1, wherein the RO unit waste outlet is connected to a waste line.

3. The system according to claim 1, wherein all of the underwater pods of the system are located at a depth below or inside the thermocline of the seawater, or, if the local depth is insufficient to reach the thermocline, as close as feasible.

4. The system according to claim 1, further comprising a protective structure for fishing nets when some or all of the underwater pods are on the seabed.

5. The system according to claim 1, comprising a single submersible pod which can be recovered from the seabed in one recovery operation and can be installed on the seabed in one installation operation, and which includes all the specific equipment including the submersible production pump and production outlet, wherein the connection with the single submersible pod consists of power and control in addition to the discharge of desalinated water.

6. The system according to claim 1, comprising several submarine pods, each comprising several submarine pods, one or more submarine pods having a submarine production pump, and / or one or more submarine treatment pods having a seawater inlet and a pretreatment stage, and / or one or more submarine treatment pods having a seawater inlet, a pretreatment stage and a water supply pump, and / or one or more submarine treatment pods having a seawater inlet, a pretreatment stage, a water supply pump and a submarine RO unit, and / or one or more submarine treatment pods having a water supply pump and a submarine RO unit, and / or a number of submarine pretreatment RO pods coupled with a smaller number of production pumps arranged on separate or combined submarine pods, the number of submarine pretreatment RO pods arranged together with a common production flow line that leads the production freshwater to a location above the seawater surface.

7. The system according to claim 1, 2, 3, 4, 5, or 6, wherein some or all of the underwater pods include buoyancy tanks and / or foam systems for ballast and deballast to facilitate transport, installation, and recovery, enabling the use of smaller vessels and lifting equipment.

8. The system according to claim 1, 2, 3, 4, 5, 6, or 7, wherein the connection from the seabed to a system located on the coast or surface comprises power and control, in addition to the discharge of desalinated water.

9. The system according to claim 1, 2, 3, 4, 5, 6, or 7, wherein the underwater pod includes individually recoverable equipment items that are operably arranged.

10. The system according to any one of claims 1 to 9, comprising a submersible fluid connector, the submersible fluid connector comprising a clamped or unclamped submersible flowline connector comprising one or two flowline connectors and one connector for power or a combination of power and control for each submersible pod.

11. The system according to claim 10, further comprising a remotely operated vehicle (ROV)-operable underwater clamp connector for joining and separating flowline joints.

12. The system according to any one of claims 1 to 11, comprising a coupling portion between the underwater pre-filtration unit equipment mechanism and the underwater processing pod, which connects multiple components by pushing one component onto another.

13. The system according to any one of claims 1 to 12, comprising a transponder for positioning, positioned on a guide post, a coupling component, and / or a device mechanism.

14. The system according to any one of claims 1 to 13, comprising equipment items and / or cameras on an underwater pod, which are coupled to a control system and can be monitored from a ship used for installation and / or maintenance.

15. A method for installing, operating, and / or maintaining a system according to any one of claims 1 to 14, comprising any combination of the following steps: The steps include towing the underwater pod to the location by surface towing or other means, A step of installing the underwater pod, which includes a ballast tank filled with air, wherein the ballast tank is continuously emptied until a suitable level of negative buoyancy is reached, and thereafter the underwater pod is deployed in place. The steps of connecting the underwater pod to a more permanent structure on the seabed, using one or more connections that can be joined by or without a light work-class remotely operated vehicle (ROV), When detaching the submerged pod from the more permanent structure on the seabed, the steps include using one or more joints that can be joined by a light work-class remotely operated vehicle (ROV) or without a light work-class remotely operated vehicle (ROV), and A method characterized by including the following.

16. The method according to claim 15, wherein in the step of installing the underwater pod, the underwater pod is deployed to the location using a transponder and / or camera for positioning control.

17. The method according to claim 15, further comprising the step of using coupling and cutting, which does not require a remotely operated vehicle (ROV) when installing or retrieving pre-processing unit equipment items.

18. The method according to claim 15, 16, or 17, further comprising the step of using a feed pump at a differential pressure of 0.7 to 1 bar (70 kPa to 100 kPa), which is lower than the differential pressure of normal operation, during operation for reverse osmosis, while the differential pressure is periodically increased to 1 to 2 bar (100 kPa to 200 kPa), thereby leading the waste, which has a significant pressure, to the filter backflush and the hydrocyclone of the pretreatment unit.

19. A step of operating the system with a low recovery rate of 15 to 70% of the maximum recovery rate of the RO unit on land. The method according to claim 15, 16, 17, or 18, including the method described in claim 15, 16, 17, or 18.

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