Patent Description:
The present disclosure generally relates to controlling the salinity of a low salinity injection water during a low salinity waterflood of a hydrocarbon bearing subterranean reservoir. A variable amount of produced water (and/or a variable quality produced water) can be disposed of as a blending stream for a blended low salinity injection water. The present disclosure also relates to minimizing the weight and/or lowering a center of mass of a desalination plant of an integrated system for providing ion specific low salinity injection water.

A problem associated with low salinity water-flooding is that desalination techniques may yield water having a lower than optimal salinity for continuous injection into an oil bearing reservoir. Indeed, the desalinated water may be damaging to the oil-bearing rock formation of the reservoir and may inhibit oil recovery, for example, by causing swelling of clays in the formation. Thus, there is an optimal salinity for the injection water that provides the benefit of enhanced oil recovery and an ionic ratio which mitigates the risk of formation damage, and the optimum values may vary from formation to formation. Typically, where an oil-bearing formation comprises rock that contains high levels of swelling clays, formation damage may be avoided, while still releasing oil from the formation, when: (<NUM>) the injection water has a total dissolved solids content (TDS) in the range of <NUM> to <NUM>,<NUM> ppm, and (<NUM>) the ratio of the concentration of multivalent cations in the low salinity injection water to the concentration of multivalent cations in the connate water of the reservoir is less than <NUM>, for example, less than <NUM>.

Additionally, low salinity water-floods generally need to meet reservoir specific sulfate criteria, in that the sulfate level of the low salinity injection water should typically be controlled to a value of less than <NUM>/L (preferably, less than <NUM>/L, and more preferably, less than <NUM>/L) in order to mitigate the risk of souring or scaling of the reservoir. Souring arises through the proliferation of sulfate-reducing bacteria that use sulfate in their metabolic pathway, thereby generating hydrogen sulfide. Scaling arises from deposition of mineral scale upon mixing of a sulfate containing injection water with a connate water containing precipitate precursor cations such as barium cations.

Yet a further problem arises offshore in that there is a need to dispose of increasing amounts of produced water during a low salinity waterflood. It is generally prohibited to dispose of produced water into a body of water (e.g., the ocean). It may therefore be necessary and beneficial to dispose of the produced water (PW) by blending with a low salinity injection water. Moreover, reinjection of the blended PW may also reduce the required capacity of the desalination plant necessary for reservoir pressure management. The quantity and quality of the PW that is required to be blended with the low salinity injection water may vary over the life of the low salinity waterflood. Prior art desalination systems are disclosed in <CIT>, <CIT> and <CIT>.

The present disclosure discloses a desalination system according to claim <NUM> and an integrated system according to claim <NUM>. Preferred embodiments are disclosed in dependent claims <NUM>-<NUM> and <NUM>-<NUM>.

For a detailed description of the disclosed embodiments of the invention, reference will now be made to the accompanying drawings in which:.

The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness.

In the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to. " Also, the term "couple" or "couples" is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms "axial" and "axially" generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms "radial" and "radially" generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. Any reference to up or down in the description and the claims will be made for purposes of clarity, with "up", "upper", "upwardly" or "upstream" meaning toward the surface of the borehole and with "down", "lower", "downwardly" or "downstream" meaning toward the terminal end of the borehole, regardless of the borehole orientation.

Throughout the following description, the following terms are referred to:
"High salinity feed water" is the feed water for a desalination plant and is typically seawater (SW), estuarine water, aquifer water or mixtures thereof.

An "ultrafiltration (UF) filtration unit" comprises a pressure vessel containing one or more UF elements; preferably, between <NUM> and <NUM> membrane elements and, in particular, between <NUM> and <NUM> UF membrane elements.

A "reverse osmosis (RO) membrane separation unit" comprises a pressure vessel, alternatively called a housing, containing one or more RO membrane elements; preferably, between <NUM> and <NUM> RO membrane elements and, in particular, between <NUM> and <NUM> RO membrane elements.

A "nanofiltration (NF) filtration unit" comprises a pressure vessel containing one or more NF elements; preferably, between <NUM> and <NUM> membrane elements and, in particular, between <NUM> and <NUM> NF membrane elements.

An "ultrafiltration (UF) stage of a desalination plant" is a group of UF filtration units connected together in parallel. Similarly, a "reverse osmosis (RO) stage of a desalination plant" is a group of RO membrane separation units connected together in parallel, and a "nanofiltration (NF) stage of a desalination plant" is a group of NF filtration units connected together in parallel.

A "membrane block" comprises stages of RO membrane separation and NF filtration connected together to provide concentrate staging and typically shares common valving and piping. A membrane block of two or more membrane blocks may be mounted on a support structure.

"Produced water (PW)" is water separated from oil and gas at a production facility. Produced water may comprise connate water, invading aquifer water from an underlying aquifer or any previously injected aqueous fluid such as seawater (SW).

"Connate water" is the water present in the pore space of an oil-bearing layer of a reservoir.

"Quality of the produced water (PW) blending stream" relates to the total dissolved solids content and/or the concentrations of individual ions or types of individual ions and/or ratios of individual ions or ratios of types of individual ions in the PW.

"TDS content" is the total dissolved solids content of an aqueous stream and typically has units of mg/L.

The present disclosure relates to an integrated system and a method for producing a blended low salinity injection water comprising variable amounts of produced water or a variable quality of produced water while maintaining the composition of the blended low salinity injection water within a predetermined operating envelope for the main phase of a low salinity waterflood that balances maximizing enhanced oil recovery from the reservoir while minimizing the risk of formation damage, souring or scaling of the reservoir.

Referring to <FIG>, an embodiment of an integrated system <NUM> for producing a low salinity injection water for a reservoir having an oil-bearing layer <NUM> penetrated by at least one injection well <NUM> and at least one production well <NUM>. In the embodiment of <FIG>, integrated system <NUM> generally includes a production system <NUM>, an injection system <NUM>, and a desalination system <NUM>. Production system <NUM> of the integrated system <NUM> generally includes a production facility or platform <NUM> disposed above the waterline <NUM> and supported by a support structure <NUM> extending between the production platform <NUM> and the sea floor <NUM>. Production platform <NUM> is in fluid communication with production well <NUM> via a production line or riser <NUM> extending between production platform <NUM> and production well <NUM>. Additionally, the production platform <NUM> of production system <NUM> includes a produced water (PW) flowline <NUM> in fluid communication with injection system <NUM>. During operation of integrated system <NUM>, fluids produced from the production well <NUM> are passed to the production platform <NUM> via production line <NUM>. The produced fluids are separated in the production platform <NUM> into an oil stream, a gaseous stream, and a PW blending stream. The PW blending stream flows to injection system <NUM> via PW flowline <NUM> for processing via injection system <NUM> before being injected into the injection well <NUM>.

In this embodiment, injection system <NUM> generally includes an injection facility or platform <NUM> disposed above the waterline <NUM> and supported by a support structure <NUM> extending between the production platform <NUM> and the sea floor <NUM>. Although in this embodiment injection system <NUM> includes injection platform <NUM>, in other embodiments, injection system <NUM> may be supported on a floating vessel such as a ship or spar. Injection platform <NUM> is in fluid communication with injection well <NUM> via an injection line or riser <NUM> extending between injection platform <NUM> and injection well <NUM>. In this embodiment, injection platform <NUM> of injection system <NUM> includes a blending system or manifold <NUM> in fluid communication with PW flowline <NUM> and a permeate flowline <NUM> extending between desalination system <NUM> and injection platform <NUM>. Blending manifold <NUM> of injection platform <NUM> is configured to blend the PW blending stream provided by PW flowline <NUM> with a permeate blending steam provided by permeate flowline <NUM> to form a blended low salinity injection water stream. In some embodiments, a concentrate may be added to the blended low salinity injection water stream to adjust the ionic balance of the low salinity injection water stream and thereby minimize the risk of formation damage due to low salinity clay swelling. Injection platform <NUM> further includes one or more high pressure injection pumps <NUM> for pumping the low salinity injection water stream formed by blending manifold <NUM> into injection well <NUM> via injection riser <NUM>.

In this embodiment, integrated system <NUM> additionally includes a control system <NUM> configured to control the operation of injection system <NUM> and/or a desalination system to thereby control the composition of the low salinity injection water stream pumped into injection well <NUM> from the injection platform <NUM> of injection system <NUM>. Boundary values for the composition of the low salinity injection water stream may be inputted into the control system <NUM>, where the boundary values define an operating envelope for the composition of the low salinity injection water stream. The operating envelope may be defined by boundary values (upper and lower limits) for one or more of the total dissolved solids (TDS) content (salinity), ionic strength, the concentrations of individual ions (such as sulfate anions, nitrate anions, calcium cations or magnesium cations), the concentrations of types of individual ions (such as monovalent cations, monovalent anions, multivalent anions, multivalent cations, or divalent cations), ratios of types of individual ions, or ratios of individual ions (such as Sodium Adsorption Ratio).

Sodium Adsorption Ratio (SAR) is used to assess the state of flocculation or of dispersion of clays in the reservoir rock. Typically, sodium cations facilitate dispersion of clay particles while calcium and magnesium cations promote their flocculation. A formula for calculating the Sodium Adsorption Ratio (SAR) is presented below in equation (<NUM>), where sodium, calcium, and magnesium cation concentrations of the low salinity injection water stream are expressed in milliequivalents per litre: <MAT>.

Compositions within the operating envelope of the low salinity injection water stream are those predicted to achieve enhanced oil recovery (EOR) from the reservoir while avoiding or minimizing the risk of formation damage. Where there is a souring risk or scaling risk for the oil bearing layer of the reservoir, compositions within the operating envelope are preferably those that are also predicted to mitigate reservoir souring or to inhibit scaling. The person skilled in the art will understand that not all reservoirs present a souring risk or a scaling risk. Thus, souring may occur when a reservoir contains an indigenous population of sulfate reducing bacteria that obtain energy by oxidizing organic compounds while reducing sulfate to hydrogen sulfide. Scaling may occur when a connate water containing high levels of precipitate precursor cations, such as barium and strontium cations, mixes with an injection water containing relatively high amounts of sulfate anions, resulting in the precipitation of insoluble sulfate salts (mineral scales).

Different boundary values for each parameter may be inputted into the control system <NUM>, thereby defining different operating envelopes for the composition of the low salinity injection water where the different operating envelopes balance different levels of EOR with different levels of risk of formation damage, reservoir souring or scaling. In order to maintain the composition of the low salinity injection water stream within a predefined or predetermined operating envelope, the amounts permeate stream blended with the PW stream via blending manifold <NUM> may be adjusted in real time by control system <NUM> in response to changes (increases or decreases) in the amount or flow rate of the PW stream to be disposed of in the low salinity injection water stream or changes in the quality (increases or decreases in the TDS content, concentration of one or more individual ions, concentration of one or more types of individual ions, a ratio of individual ions or a ratio of types of individual ions) of the PW. In some embodiments, control system <NUM> is configured to selectably add or inject site specific ions as a concentrate to the low salinity injection water stream to balance the ionic composition and to prevent, or at least reduce, the risk of clay swelling and formation damage.

In this embodiment, the desalination system <NUM> of integrated system <NUM> generally includes a desalination facility or platform <NUM> disposed above the waterline <NUM> and supported by a support structure <NUM> extending between the desalination platform <NUM> and the sea floor <NUM>. Desalination platform <NUM> is in fluid communication with a body of water <NUM> (e.g., the sea) positioned between the waterline <NUM> and sea floor <NUM> via a feed or inlet conduit <NUM> that extends between the body of water <NUM> and the desalination platform <NUM>. During operation of integrated system <NUM>, an input or feed water stream comprising high salinity feed water supplied to desalination platform <NUM> by feed conduit <NUM> is treated by equipment of desalination system <NUM> to thereby form the permeate stream provided to injection system <NUM> via permeate flowline <NUM>.

Desalination platform <NUM> has a center of mass <NUM> disposed at a vertical distance Dp above the sea floor <NUM>. The support structure <NUM> of desalination system <NUM> is coupled or affixed to the sea floor <NUM> at a foundation <NUM>. In this configuration, it may be advantageous to minimize the distance Dp between the center of mass <NUM> of desalination platform <NUM> and the sea floor <NUM> to increase the stability of desalination platform <NUM> and support structure <NUM> (e.g., to decrease buckling and/or bending loads resulting from interactions between desalination platform <NUM> and support structure <NUM> and the surrounding environment). For example, a desalination platform having an elevated center of mass may require a more robust and expensive support structure in order to provide adequate stability for the desalination platform. Thus, by minimizing the distance Dp between the center of mass <NUM> of desalination platform <NUM> and the sea floor <NUM>, adequate stability may be provided for the desalination platform <NUM> while minimizing the costs associated with constructing, transporting, and maintaining support structure <NUM>. For similar reasons, minimizing the mass or weight of desalination platform <NUM> may also provide a means for saving costs associated with the construction, transportation, and maintenance of support structure <NUM> while providing adequate stability and structural support for desalination platform <NUM>.

Referring to <FIG> and <FIG>, a schematic representation of the desalination system <NUM> of the integrated system <NUM> of <FIG> is shown in <FIG>. In the embodiment of <FIG> and <FIG>, the desalination system <NUM> of integrated system <NUM> generally includes one or more feed water lift pumps <NUM>, a filter array <NUM>, a heat exchanger array <NUM>, a fine filtration stage <NUM>, a buffer tank <NUM>, one or more high pressure pumps <NUM>, a cleaning-in-place (CIP) skid <NUM>, a membrane block <NUM>, a dump tank <NUM>, and a deaerator <NUM>. Lift pumps <NUM> are configured to lift or pump a feed water stream (e.g., seawater) from the body of water <NUM> via feed conduit <NUM>. Filter array <NUM> is in fluid communication with a discharge <NUM> of high pressure pumps <NUM> and is configured to filter particulates entrained in the feed water stream provided by high pressure pumps <NUM>, thereby providing a filtered feed water stream <NUM> at an outlet thereof. In this embodiment, filter array <NUM> comprises one or more <NUM> micron filters; however, in other embodiments, the configuration of filter array <NUM> may vary. The filtered feed water stream <NUM> is provided to heat exchanger array <NUM> where the filtered feed water stream 41is heated prior to flowing to fine filtration stage <NUM> as a heated feed water stream <NUM>. In this embodiment, heat exchanger array <NUM> comprises one or more plate heat exchangers configured to heat the filtered feed water stream to a temperature of at least <NUM>° Celsius; however, in other embodiments, the configuration and functionality of heat exchanger array <NUM> may vary. The heating of filtered feed water stream <NUM> by heat exchanger <NUM> increases production at the same feed pressure of the feed water stream <NUM> to thereby reduce the weight of the desalination system <NUM>.

As will be described further herein, fine filtration stage <NUM> includes a plurality of UF skids, each UF skid including a plurality of UF filtration units connected together in parallel and mounted to a common support structure. In some embodiments, fine filtration stage <NUM> comprises microfiltration (MF) skids including a plurality of MF filtration units. In other embodiments, fine filtration stage <NUM> comprises a combination of MF skids and UF skids, and/or a plurality of fine filtration skids each including a plurality of UF and MF filtration units. The UF filtration units of fine filtration stage <NUM> operate in "dead end" and are generally configured to reject particulates, colloids, microbes, viruses, and other contaminants from the filtered feed water stream <NUM> provided to the fine filtration stage <NUM> from heat exchanger array <NUM>. In this manner, fine filtration stage <NUM> discharges an UF filtrate stream <NUM> that is formed from the heated feed water stream <NUM> supplied thereto. In some embodiments, the UF filtration units of fine filtration stage <NUM> are configured to reject materials having a molecular weight as low as approximately <NUM>,<NUM> grams/mole to <NUM>,<NUM> grams/mole; however, in other embodiments, the configuration of the UF filtration units of fine filtration stage <NUM> may vary.

The UF filtrate stream <NUM> discharged from fine filtration stage <NUM> is fed to a buffer tank <NUM>. In some embodiments, buffer tank <NUM> may have a volume of approximately between <NUM> meters cubed to <NUM> meters cubed; however, in other embodiments, the volume of buffer tank <NUM> may vary. In certain embodiments, the volume of buffer tank <NUM> is between two times to four times the volume required to backwash the UF filtration units of a single UF skid. Additionally, a portion of UF filtrate stream <NUM> may be returned periodically to fine filtration stage <NUM> as a backwash stream <NUM> for back-washing or cleaning the UF filtration units of fine filtration stage <NUM>. In this embodiment, UF filtrate stream <NUM> is pumped from buffer tank <NUM> to an inlet of membrane block <NUM> via one or more high pressure pumps <NUM> positioned between buffer tank <NUM> and the membrane block <NUM>.

As will be described further herein, membrane block <NUM> includes a plurality of RO arrays and a plurality of NF arrays, each RO array including a plurality of RO membrane separation units connected together in parallel and mounted to a common support structure along with an NF array including a plurality of NF filtration units connected together in parallel. The NF filtration units of the membrane block <NUM> operate in cross-flow and are generally configured to reject nanometer sized particles having a molecular weight as low as approximately <NUM> grams/mole to <NUM>,<NUM> grams/mole; however, in other embodiments, the configuration of the NF filtration units of membrane block <NUM> may vary. The RO membrane separation units of the membrane block <NUM> operate in cross-flow and are generally configured to reject ionic contamination, micro-organisms, particulates, and other materials having a molecular weight as low as <NUM> grams/mole to less than <NUM> grams/mole; however, in other embodiments, the configuration of the RO membrane separation units of membrane block <NUM> may vary.

The membrane block <NUM> of desalination system <NUM> discharges a combined permeate stream <NUM> that is formed from the UF filtrate stream <NUM> supplied thereto. Combined permeate stream <NUM> is discharged from membrane block <NUM> to deaerator <NUM>, and from deaerator <NUM> to the injection system <NUM> via permeate flowline <NUM> for blending with the PW steam provided by production system <NUM> via the blending manifold <NUM> of injection system <NUM>. A combined reject or concentrate stream <NUM> is directed towards dump tank <NUM> for dumping. In some embodiments, dump tank <NUM> may comprise a caisson of the desalination platform <NUM> of desalination system <NUM>. In some embodiments, membrane reject stream <NUM> is discharged through an energy recovery device to reduce energy usage.

The CIP skid <NUM> is configured for cleaning the UF skids of fine filtration stage <NUM> and the RO and NF arrays of membrane block <NUM>. CIP skid <NUM> is in fluid communication with fine filtration stage <NUM> via CIP conduits <NUM> while CIP skid <NUM> is in fluid communication with membrane block <NUM> via CIP conduits <NUM>. In this arrangement, fluid may be flowed between CIP skid <NUM> and the fine filtration stage <NUM> and membrane block <NUM> to clean stage <NUM> and block <NUM>. Particularly, CIP skid <NUM> includes a tank and one or more pumps for circulating fluid.

Referring to <FIG>, a schematic representation of the fine filtration stage <NUM> of the desalination system <NUM> of <FIG> and <FIG> is shown in <FIG>. In the embodiment of <FIG>, fine filtration stage <NUM> includes a plurality of UF skids <NUM> connected in parallel. As will be described further herein, each UF skid <NUM> comprises a plurality of UF filtration units connected in parallel. Each UF skid <NUM> receives heated feed water stream <NUM> (which results in a technical benefit by having the feed enter simultaneously via both the end inlet side ports and the center port to optimize membrane usage) and produces or discharges UF filtrate stream <NUM>. Additionally, each UF skid <NUM> receives a backwash inlet stream 46A, where backwash inlet stream 46A comprises a portion of the filtrate stream <NUM>. Each UF skid <NUM> discharges a backwash outlet stream 46B (which results in a technical benefit by taking the backwash sequentially from each of the 3x side ports) that flows to a drain of the desalination platform <NUM>. A CIP inlet stream 62A flows from CIP skid <NUM> to each UF skid <NUM> while a CIP return stream 62B flows from each UF skid <NUM> to the CIP skid <NUM>. The CIP inlet stream 62A includes water and chemicals for the chemical cleaning and flushing of the UF filtration units housed in each UF skid <NUM>. In this embodiment, streams <NUM>, <NUM>, 46A, 46B, 62A, and 62B are each conducted or flow through one of a plurality of interconnecting pipeworks <NUM> extending across the first deck 35A, where each of interconnecting pipeworks <NUM> are disposed on, and supported by pipe supports <NUM> disposed on the first deck 35A.

Referring to <FIG>, views of an embodiment of a UF skid <NUM> of the fine filtration stage <NUM> of <FIG> and <FIG> are shown in <FIG> while an embodiment of a UF filtration unit <NUM> is shown in <FIG>. Referring to <FIG>, UF skid <NUM> is supported on a deck 35A of desalination platform <NUM> and has a first end 102A, a second end 102B opposite first end 102A, a pair of opposing lateral sides <NUM>, a top or upper end 106A, and a base or lower end 106B. UF skid <NUM> generally includes a rack <NUM> of UF filtration units <NUM> (for clarity, UF filtration units <NUM> are hidden in <FIG>), a plurality of vertically extending inlet feed headers or manifolds <NUM>, a plurality of vertically extending filtrate discharge headers or manifolds <NUM>, and a support structure or frame <NUM> that physically supports the rack <NUM> of UF filtration units <NUM> and the manifolds <NUM> and <NUM>. In the embodiment of <FIG>, the UF filtration units <NUM> of rack <NUM> are arranged in ten rows, one above another with each row comprised of four UF filtration units <NUM>; however, in other embodiments, the number and arrangement of UF filtration units <NUM> of UF skid <NUM> may vary. In this embodiment, three inlet feed headers <NUM> are spaced between ends 102A, 102B of UF skid <NUM>, including two inlet feed headers <NUM> positioned at ends 102A, 102B, and one inlet feed header positioned equidistantly between ends 102A, 102B. Additionally, each inlet feed header <NUM> is positioned equidistantly between lateral sides <NUM> with one UF filtration unit <NUM> being positioned or between each pair of inlet feed headers <NUM>.

As shown particularly in <FIG>, each UF filtration unit <NUM> of UF skid <NUM> comprises a cylindrical filtration vessel <NUM> and a plurality of hollow fiber UF filtration elements or membranes <NUM> housed therein. In this embodiment, filtration vessel <NUM> extends axially between a pair of opposing ends <NUM>, and includes a pair of radial outer ports <NUM> positioned proximal to ends <NUM>, and a radial central port <NUM> positioned equidistantly between ends <NUM>. UF filtration unit <NUM> additionally includes a pair of perforated tubes <NUM> disposed centrally within filtration vessel <NUM>. Each tube <NUM> extends from an end <NUM> of filtration vessel <NUM>, and tubes <NUM> are joined via a central connector <NUM>. An outer end of each tube <NUM> is coupled to an axial end-port <NUM>. Each UF filtration element <NUM> is disposed in an annulus formed between an outer surface of one of the perforated tubes <NUM> and an inner surface of filtration vessel <NUM>. A pair of endplates <NUM> disposed at each end <NUM> of filtration vessel <NUM> seal the annulus from the surrounding environment.

An inlet feed header <NUM> of UF skid <NUM> is coupled to each port <NUM> and <NUM> of filtration vessel <NUM> while a filtrate discharge header <NUM> is coupled to each end-port <NUM>. During operation of UF filtration unit <NUM>, heated feed water stream <NUM> may flow into filtration vessel <NUM> via inlet feed headers <NUM> of UF skid <NUM>. Particularly, heated feed water stream <NUM> is supplied to the annular spaces formed between the outer surface of each end-port <NUM> and the inner surface of filtration vessel <NUM> via outer ports <NUM>. Heated feed water stream <NUM> is also supplied to the annular space formed between the outer surface of central connector <NUM> and the inner surface of filtration vessel <NUM> via central port <NUM>. Given that neither end-ports <NUM> nor central connector <NUM> are perforated, the heated feed water stream <NUM> is forced to flow axially into and radially through the fibers of each UF filtration element <NUM> before it may enter one of the perforated tubes <NUM> and exit filtration vessel <NUM> via one of the end-ports <NUM>.

During backwashing of each UF filtration unit <NUM>, UF filtrate stream <NUM> flows into perforated tubes <NUM> via filtrate discharge headers <NUM> and end-ports <NUM>. The UF filtrate stream <NUM> then flows into the annuli formed between perforated tubes <NUM> and filtration vessel <NUM>, and then radially through the fiber walls exiting axially along the fibers of the UF filtration elements <NUM> before sequentially exiting filtration vessel <NUM> via ports <NUM> and <NUM>. In this manner, impurities collected in UF filtration elements <NUM> may be backwashed into inlet feed headers <NUM> and thereby removed from UF filtration elements <NUM>.

As shown particularly in <FIG>, UF skid <NUM> includes inlet feed pipework <NUM> coupled to inlet feed headers <NUM>, inlet feed pipework <NUM> extending from a terminal or inlet end 114A that is coupled to an inlet feed valve <NUM> for controlling the inlet of heated feed water stream <NUM> to inlet feed headers <NUM> and UF filtration units <NUM>. UF skid <NUM> also includes filtrate discharge pipework <NUM> coupled to filtrate discharge headers <NUM>, filtrate discharge pipework <NUM> extending from a terminal or discharge end 122A that is coupled to an permeate discharge valve <NUM> for isolating the discharge of UF filtrate stream <NUM> from the UF skid <NUM>. As shown particularly in <FIG>, in this embodiment, additional inlet pipework valves <NUM> are disposed along inlet feed pipework <NUM> for controlling fluid flow through inlet feed pipework <NUM>.

UF skid <NUM> includes a backwash inlet pipework <NUM> connected to the filtrate discharge pipework <NUM> and a backwash discharge pipework <NUM> connected to inlet feed pipe work <NUM>, where a backwash inlet valve <NUM> is disposed along backwash inlet pipework <NUM> for isolating the UF skid <NUM> from backwash stream <NUM>. Pipework valves <NUM> are configured for sequentially directing the flow of backwash stream <NUM> through the UF filtration elements <NUM> to maximize backwash efficacy. Additionally, a plurality of backwash discharge valves <NUM> are disposed along backwash discharge pipework <NUM> for controlling fluid flow therethrough to waste. In this embodiment, fine filtration stage <NUM> includes a remotely positioned valve <NUM> for isolating each UF skid <NUM> of fine filtration stage <NUM> from the backwash stream <NUM>. In this embodiment, a chemical injection line <NUM> is connected to backwash inlet pipework <NUM> between backwash inlet valve <NUM> and the remotely positioned valve <NUM>, a chemical injection valve <NUM> being disposed along chemical injection line <NUM> for controlling fluid flow therethrough. Chemical injection line <NUM> provides for the injection of chemicals, such as hypochlorite or other chemicals configured to assist in the cleaning and disinfection of UF filtration units <NUM>, into the UF filtrate stream <NUM> flowing through backwash inlet pipework <NUM> during the backwashing of UF skid <NUM>. Additionally, in some embodiments, a nonoxidizing disinfectant may be injected to the heated feed water stream <NUM> up stream of inlet feed valve <NUM>. Additionally, in this embodiment, a plurality of branch conduits <NUM>, with a branch valve <NUM> disposed along each branch conduit <NUM>, extend between filtrate discharge pipework <NUM> and backwash discharge pipework <NUM> and a CIP discharge pipework <NUM> of UF skid <NUM> to assist with the drainage of filtrate discharge pipework <NUM> and the filtrate discharge headers <NUM> coupled therewith.

UF skid <NUM> includes a CIP inlet pipework <NUM> connected with inlet feed pipework <NUM> and including a CIP inlet valve <NUM> for selectably admitting fluid from CIP assembly to inlet feed pipework <NUM>. In this embodiment, an air injection pipework <NUM>, including an air injection valve <NUM> disposed along air injection pipework <NUM>, is connected to CIP inlet pipework <NUM> for testing the integrity of the installed UF skid <NUM>. UF skid <NUM> also includes a CIP discharge pipework <NUM> connected to backwash discharge pipework <NUM>. A CIP discharge valve <NUM> is disposed along CIP discharge pipework <NUM> for controlling the flow of fluid from CIP discharge pipework <NUM> to CIP assembly <NUM>. UF skid <NUM> additionally includes a vent pipework <NUM> connected to both the inlet feed headers <NUM> and the filtrate discharge headers <NUM> for removing air from the UF filtration units <NUM> and headers <NUM> and <NUM>. Drainage valves <NUM> are disposed along the drainage pipework to provide a common opening for the drainage pipework for controlling fluid flow therethrough. In some embodiments, one or more of the valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of UF skid <NUM> are remotely controlled by the control system <NUM> of integrated system <NUM>.

As shown particularly in <FIG>, in this embodiment, support structure <NUM> of UF skid <NUM> generally includes a rectangular upper frame <NUM> positioned at the top 106A of UF skid <NUM>, a rectangular lower frame <NUM> positioned at the base 106B of UF skid <NUM>, a plurality of vertical support members <NUM>, and a plurality of support racks <NUM>. Upper frame <NUM> includes a laterally extending central support member <NUM> disposed equidistantly between the front and rear ends 102A, 102B of UF skid <NUM>. Lower frame <NUM> also includes a laterally extending support member <NUM> that is supported by a pair of vertical supports <NUM>.

Each vertical support members <NUM> of support structure <NUM> is disposed at a corner of UF skid <NUM> and extends vertically between upper frame <NUM> and lower frame <NUM>. Support racks <NUM> are positioned at the front and rear ends 102A, 102B of UF skid <NUM> and extend between lateral sides <NUM>. Support structure <NUM> additionally includes a pair of vertical support <NUM> positioned at the ends 102A, 102B of UF skid <NUM>, each vertical support <NUM> positioned equidistantly between the lateral sides <NUM> of UF skid <NUM>. Each vertical support <NUM> extends vertically between a lowermost support rack 180A and the upper frame <NUM> of support structure <NUM>, where each support rack <NUM> extends laterally between one of the lateral sides <NUM> of UF skid <NUM> and one of the vertical supports <NUM>. In this embodiment, support frames <NUM>, <NUM>, and members <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> each comprise metallic (e.g., carbon steel, alloy steel, etc.) I-beams; however, in other embodiments, support frames <NUM>, <NUM>, and members <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may comprise varying cross-sectional shapes and materials.

In the configuration of UF skid <NUM> described above, headers <NUM>, <NUM> and pipeworks <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are each directly supported by the lower frame <NUM> of support structure <NUM>. Particularly, with one or more embodiments, only the rack <NUM> of UF filtration units <NUM> is directly supported by a member of support structure <NUM> that is elevated from the lower frame <NUM>. The UF filtration units <NUM> of rack <NUM> contact, and are physically supported by support racks <NUM>, which are spaced from lower frame <NUM>. Thus, upper frame <NUM> of support structure <NUM> is not required to support the weight of headers <NUM>, <NUM> and pipeworks <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. By supporting the components of UF skid <NUM> at the lower frame <NUM> thereof rather than at the upper frame <NUM>, the total weight of support structure <NUM> may be minimized given that the loads supported by upper frame <NUM> and vertical support members <NUM> may, in-turn, be minimized. For example, with one or more embodiments, because the loads supported by upper frame <NUM> and vertical support members <NUM> are minimized, upper frame <NUM> and vertical support members <NUM> can be formed using lighter-weight materials. With one or more embodiments, upper frame <NUM> and vertical support members <NUM> can be constructed in a manner that reduces the total weight of support structure <NUM>. With one or more embodiments, the center of mass of UF skid <NUM> is in the lower half of UF skid <NUM>.

Additionally, valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of UF skid <NUM> are each positioned proximal to lower frame <NUM> and distal to upper frame <NUM> of support structure <NUM>. In other words, valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are positioned nearer to the lower frame <NUM> than to the upper frame <NUM> of support structure <NUM>. With valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of UF skid <NUM> positioned proximal to lower frame <NUM>, the distance between the deck 35A and a center of mass of the UF skid <NUM> is minimized, thereby reducing the vertical distance Dp between the sea floor <NUM> and the center of mass <NUM> of the desalination platform <NUM>. Further, given that valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of UF skid <NUM> are positioned proximal to lower frame <NUM>, the fluid conduits used to convey heated feed water stream <NUM>, UF filtrate stream <NUM>, and CIP streams 62A, 62B may each be supported by, and positioned proximal to, deck 35A (rather than suspended from above in a position distal to deck 35A), further reducing the vertical distance Dp between the sea floor <NUM> and the center of mass <NUM> of the desalination platform <NUM>. As described above, reducing the weight and lowering the center of mass <NUM> of the desalination platform <NUM> increases the stability of platform <NUM> and minimizes the costs associated with constructing, transporting, and maintaining support structure <NUM> of the desalination system <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, a schematic representation of the membrane block <NUM> of the desalination system <NUM> of <FIG> and <FIG> is shown in <FIG>. In the embodiment of <FIG>, membrane block <NUM> includes a plurality of membrane skids <NUM> connected in parallel. In this embodiment, membrane block <NUM> includes two fewer membrane skids <NUM> than UF arrays <NUM> of the fine filtration stage <NUM>; however, in other embodiments, the number of membrane skids <NUM> and UF skids <NUM> of the desalination system <NUM> may vary. As will be described further herein, each membrane skid <NUM> comprises a plurality of RO membrane separation units and a plurality of NF filtration units. Each membrane skid <NUM> receives UF filtrate stream <NUM> from high pressure pumps <NUM> and produces or discharges the combined membrane permeate stream <NUM>, which comprises a blend of RO permeate and NF permeate, as will be described further herein. In other embodiments, each membrane skid <NUM> may discharge three separate permeate streams <NUM> (e.g., two RO permeate streams and an NF permeate stream, etc.) that are subsequently blended downstream in different proportions to achieve a desired low salinity specification; however, in other embodiments, each membrane skid <NUM> may discharge varying numbers of membrane permeate streams <NUM>. Additionally, each membrane skid <NUM> discharges a RO reject or concentrate stream 49A and an NF reject or concentrate stream 49B, as will be described further herein, which flow to dump tank <NUM> of the desalination platform <NUM> as combined concentrate stream <NUM>. A CIP inlet stream 64A flows from CIP skid <NUM> to each membrane skid <NUM> while a CIP return stream 64B flows from each membrane skid <NUM> to the CIP skid <NUM>. The CIP inlet stream 64A includes water and chemicals for the chemical cleaning and flushing of the RO and NF filtration units housed in each membrane skid <NUM>. In this embodiment, streams <NUM>, <NUM>, 49A, 49B, 64A, and 64B are each conducted through or flowed through one of the plurality of interconnecting pipeworks <NUM> extending across the first deck 35B, where each of interconnecting pipeworks <NUM> are disposed on, and supported by pipe supports <NUM> disposed on the first deck 35B.

Referring to <FIG>, views of an embodiment of a membrane skid <NUM> of the membrane block <NUM> of <FIG> and <FIG> are shown in <FIG> while an embodiment of an UF filtration unit <NUM> is shown in <FIG>. Membrane skid <NUM> is supported on a deck 35B of desalination platform <NUM> and has a first end 302A, a second end 302B opposite first end 302A, a pair of opposing lateral sides <NUM>, a top or upper end 306A, and a base or lower end 306B. In some embodiments, deck 35B of desalination platform <NUM> may comprise the same deck as the deck 35A on which UF skids <NUM> are disposed, while in other embodiments, deck 35B may comprise a deck separate from deck 35A (e.g., deck 35B may comprise a deck disposed above or below deck 35A).

Membrane skid <NUM> generally includes a first or Lower rack 310A of RO membrane separation units <NUM>, a second or upper rack 310B of RO membrane separation units <NUM>, a rack <NUM> of NF filtration units <NUM> (for clarity, RO membrane separation units <NUM> and NF filtration units <NUM> are hidden in <FIG>), a plurality of vertically extending lower inlet feed headers or manifolds 312A, a plurality of vertically extending upper inlet feed headers or manifolds 312B, a vertically extending lower permeate discharge header or manifold 320A, a vertically extending upper permeate discharge header or manifold 320B, a vertically extending lower concentrate discharge header or manifold 330A, a vertically extending upper concentrate discharge header or manifold 330B, and a support structure or frame <NUM> that physically supports the racks 310A, 310B, and <NUM> of RO membrane separation units <NUM> and NF filtration units <NUM>, respectively and the manifolds 312A, 312B, 320A, 320B, 330A, and 330B. In some embodiments, rack <NUM> of each membrane skid <NUM> may comprise a rack <NUM> of RO membrane separation units <NUM>. In other embodiments, racks 310A and 310B of each membrane skid <NUM> may comprise racks 310A and 310B of NF filtration units <NUM>. In this embodiment, as will be described further herein, racks 310B and <NUM> operate in parallel, each being connected in series with respect to the lower rack 310A.

In the embodiment of <FIG>, the RO membrane separation units <NUM> of lower rack 310A are arranged in six rows, one above another with each row comprised of six RO membrane separation units <NUM>; the RO membrane separation units <NUM> of upper rack 310B are arranged in eight rows, one above another with each row comprised of six RO membrane separation units <NUM>; and the NF filtration units <NUM> of rack <NUM> are arranged in one row comprised of four NF filtration units <NUM>. However, in other embodiments, the number and arrangement of RO membrane separation units <NUM> and NF filtration units <NUM> of membrane skid <NUM> may vary. Inlet feed headers 312A and 312B are positioned proximal the ends 302A, 302B of membrane skid <NUM>. Permeate discharge headers 320A and 320B are each positioned proximal to the second end 302B of membrane skid <NUM>. Concentrate discharge headers 330A and 330B are each positioned equidistantly between the ends 302A and 302B of membrane skid <NUM>.

Each RO membrane separation unit <NUM> of membrane skid <NUM> comprises a cylindrical vessel, a perforated tube disposed within the vessel, and a plurality of RO membrane separation elements or membranes disposed radially between the perforated tube and the cylindrical vessel. Each RO membrane separation unit <NUM> includes a pair of outer radial ports positioned proximal to each end of the cylindrical vessel, where each outer radial port is in fluid communication with one of the inlet feed headers 312A, 312B. The cylindrical vessel also includes a central radial port positioned equidistantly between the outer radial ports, the central radial port being in fluid communication with one of the concentrate discharge headers 330A, 330B. The perforated tube of each RO membrane separation unit <NUM> includes an axial port at an end of the cylindrical vessel positioned proximal to the second end 302B of membrane skid <NUM>, where the axial port is in fluid communication with one of the permeate discharge headers 320A, 320B. In this embodiment, each RO membrane separation unit <NUM> houses two sets of three RO separation elements; however, in other embodiments, the number of RO separation elements of each RO membrane separation unit <NUM> may vary.

As shown particularly in <FIG>, during operation of RO membrane skid <NUM>, UF filtrate stream <NUM> flows into the RO membrane separation units <NUM> of the lower rack 310A of membrane skid <NUM> via lower inlet feed headers 312A and the outer radial ports of each RO membrane separation unit <NUM>. The UF filtrate stream <NUM> then flows through the RO membrane elements disposed within each RO membrane separation unit <NUM> of lower rack 310A. The UF filtrate stream <NUM> is divided as it flows through RO membrane elements into a first RO permeate stream 47A and a first or initial RO reject or concentrate stream <NUM>. The first RO permeate stream 47A exits each RO membrane separation unit <NUM> of lower rack 310A via the axial port of each RO membrane separation unit <NUM>, where the RO permeate steam 47A flows into lower permeate discharge header 320A. The first RO concentrate stream <NUM> exits each RO membrane separation unit <NUM> of lower rack 310A via the central radial port of the filtration vessel of each RO membrane separation unit <NUM> and flows into the lower concentrate discharge header 330A.

The RO membrane separation units <NUM> of the upper rack 310B of membrane skid <NUM> are configured similarly as the RO membrane separation units <NUM> of lower rack 310A. However, instead of receiving UF filtrate stream <NUM> via the outer radial ports of each RO membrane separation unit <NUM>, the outer radial ports of each membrane separation unit <NUM> of upper rack 310B receives a first portion 313A of the first RO concentrate stream <NUM> discharged by the RO membrane separation units <NUM> of lower rack 310A. The first portion 313A of the first RO concentrate stream <NUM> is divided as it flows through the RO membrane separation units <NUM> of upper rack 310B into a second RO permeate stream 47B and the RO concentrate stream 49A, where RO concentrate stream 49A comprises a second or final RO concentrate stream 49A. The second RO permeate stream 47B exits each RO membrane separation unit <NUM> of upper rack 310B via the axial port of each RO membrane separation unit <NUM>, where the second RO permeate steam 47B flows into upper permeate discharge header 320B. The central radial port of each RO membrane separation unit <NUM> of upper rack 310B discharges the second RO concentrate stream 49A to dump tank <NUM>. In some embodiments, the central radial port of each RO membrane separation unit <NUM> of upper rack 310B discharges the second RO concentrate stream 49A to an energy recovery device.

Each NF filtration unit <NUM> of membrane skid <NUM> comprises a cylindrical filtration vessel, a perforated tube disposed within the filtration vessel, and a plurality of NF filtration elements or membranes disposed radially between the perforated tube and the cylindrical vessel. The cylindrical vessel of each NF filtration unit <NUM> includes a pair of outer radial ports positioned proximal each end of the cylindrical vessel, where each outer radial port is in fluid communication with the lower concentrate discharge header 330A. The cylindrical vessel also includes a central radial port <NUM> (shown schematically in <FIG>) positioned equidistantly between the outer radial ports. The perforated tube of each NF filtration unit <NUM> includes an axial port at an end of the cylindrical vessel positioned proximal to the second end 302B of membrane skid <NUM>, where the axial port is in fluid communication with the combined RO permeate discharge from headers 320A, 320B via RO permeate pipeworks 321A, 321B, respectively, extending therefrom. In this embodiment, each NF filtration unit <NUM> houses two sets of three NF filtration elements; however, in other embodiments, the number of NF filtration elements of each NF filtration unit <NUM> may vary.

As shown particularly in <FIG>, during operation of membrane skid <NUM>, a first portion 313A of the first RO concentrate stream <NUM> flows into the NF filtration units <NUM> as a reduced pressure NF feed stream <NUM> via the outer radial ports of the filtration vessel of each NF filtration unit <NUM>. The NF feed stream <NUM> flows through the NF filtration elements disposed within the NF filtration unit <NUM>. The NF feed stream <NUM> is divided as it flows through NF filtration elements into an NF permeate stream 47C and the NF reject concentrate stream 49B (membrane reject stream <NUM> of <FIG> comprising the downstream combination of second RO concentrate stream 49A and NF concentrate stream 49B). The NF permeate stream 47C exits each NF filtration unit <NUM> via the axial port of each NF filtration unit <NUM>. The NF concentrate stream 49B exits each NF filtration unit <NUM> via the central radial port <NUM> of the filtration vessel of each NF filtration unit <NUM>.

As shown particularly in <FIG> and <FIG>, membrane skid <NUM> includes an inlet feed pipework <NUM> carrying UF filtrate stream <NUM>, a first RO concentrate pipework <NUM> extending from lower concentrate discharge header 330A and carrying first RO concentrate stream <NUM>, lower RO permeate pipework 321A extending from lower permeate discharge header 320A, upper RO permeate pipework 321B extending from upper permeate discharge header 320B, combined permeate pipework <NUM> that is coupled to RO permeate pipeworks 321A, 321B and an NF permeate pipework <NUM> extending from NF filtration units <NUM>, a second RO concentrate pipework <NUM>, an NF concentrate pipework <NUM>, a CIP inlet pipework <NUM>, and a CIP discharge pipework <NUM>. In this embodiment, UF filtrate stream <NUM> flows through inlet feed pipework <NUM> of membrane skid <NUM>, where inlet feed pipework <NUM> is coupled to the lower inlet feed headers 312A, inlet feed pipework <NUM> extending from a terminal or inlet end 314A that is coupled to an inlet feed valve <NUM> for controlling the inlet of UF filtrate stream <NUM> to lower inlet feed headers 312A and the RO membrane separation units <NUM> of lower rack 310A.

In this embodiment, membrane skid <NUM> also includes a low flow bypass valve <NUM> coupled to inlet feed pipework <NUM> for bypassing inlet feed valve <NUM> to provide for the flushing of membrane skid <NUM> during start up. Additionally, a plurality of feed valves <NUM> is disposed along inlet feed pipework <NUM> for controlling fluid flow therethrough. First RO concentrate stream <NUM> flows through the first RO concentrate pipework <NUM> of membrane skid <NUM>. First RO concentrate pipework <NUM> extends between lower concentrate discharge header 330A and the upper inlet feed headers 312B. First RO concentrate pipework <NUM> also extends between lower concentrate discharge header 330A and the outer radial ports of each NF filtration unit <NUM>. A plurality of RO concentrate valves <NUM> are disposed along first RO concentrate pipework <NUM> for controlling fluid flow therethrough. Particularly, one of the RO concentrate valves <NUM> (shown as RO concentrate valve 319A in <FIG>) controls the flow rate and pressure of the NF feed stream <NUM> flowing to the NF filtration units <NUM>.

The combined permeate pipework <NUM> of membrane skid <NUM> connects with the RO permeate pipeworks 321A, 321B, and the NF permeate pipework <NUM>, and extends to a terminal or discharge end 322A that is coupled to a permeate discharge valve <NUM> for isolating the combined permeate stream <NUM>. In this embodiment, the combined permeate stream <NUM> comprises a blend of the upper RO permeate stream 47A discharged from lower rack 310A, the NF permeate stream 47C discharged from rack <NUM>, and a lower RO permeate stream 47C discharged from upper rack 310B. Additionally, membrane permeate pipework <NUM> extends from the axial port of each NF filtration unit <NUM> to discharge end 322A. Further, a plurality of permeate valves <NUM> are disposed along membrane permeate pipework <NUM> for controlling fluid flow therethrough. In this configuration, RO permeate streams 47A, 47B, and at least a portion of the NF permeate stream 47C each flow through, and are mixed or blended in, permeate pipework <NUM> prior to being discharged from membrane skid <NUM> at the permeate discharge valve <NUM>. Particularly, an NF permeate control valve 333A is disposed along NF concentrate pipework <NUM> for controlling the proportion of the NF permeate stream 47C supplied to permeate pipework <NUM>. In this embodiment, lower RO permeate pipework 321A is connected to a lower vent valve 325A and upper permeate pipework 321B is connected to an upper vent valve 325B for venting the RO permeate streams 47A and 47B, respectively. Lower vent valve 325A and upper vent valve 325B may be operated to remove air and prevent over pressurization or vacuum in the racks 310A, 310B of RO membrane separation units <NUM> during startup and shutdown of membrane skid <NUM>. Additionally, the permeate valve <NUM> disposed along lower RO permeate pipework 321A may be operated to regulate the flow of first RO permeate stream 47A and second RO permeate stream 47B by placing backpressure on lower rack 310A of RO membrane separation units <NUM>, where an increase in backpressure on lower rack 310A increases production from upper rack 310B. In this manner, over-fluxing of lower rack 310A may be avoided and beneficial turbulent flow through upper rack 310B may be maintained, potentially optimizing long term production reliability.

The second RO concentrate pipework <NUM> of membrane skid <NUM> extends from upper concentrate discharge header 330B to a RO concentrate discharge valve <NUM> for controlling the discharge of RO concentrate stream 49A from the membrane skid <NUM>. In some embodiments, second RO concentrate pipework <NUM> discharges RO concentrate stream 49A to an energy recovery device. The NF concentrate pipework <NUM> of membrane skid <NUM> extends from the central radial ports of NF filtration units <NUM> to a terminal or discharge end 331A. Additionally, NF concentrate pipework <NUM> is connected to the NF permeate pipework <NUM> to allow for the controlled dumping of excess NF permeate stream 47C via NF permeate control valve 333A. Additionally, an NF concentrate valve 333B is disposed along NF concentrate pipework <NUM> for controlling the flow of NF concentrate through NF concentrate pipework <NUM>.

The CIP inlet pipework <NUM> of membrane skid <NUM> connects with inlet feed pipework <NUM>, first RO concentrate pipework <NUM>, and NF filtration units <NUM>. CIP inlet pipework <NUM> includes a plurality of CIP inlet valves <NUM> for controlling the flow of fluid of CIP inlet stream 64A from CIP assembly <NUM> to inlet feed pipework <NUM>, first RO concentrate pipework <NUM>, and the NF filtration units <NUM>. CIP discharge pipework <NUM> of membrane skid <NUM> connects with first RO concentrate pipework <NUM>, second RO concentrate pipework <NUM>, and NF concentrate pipework <NUM>. CIP discharge pipework <NUM> includes a plurality of CIP discharge valves <NUM> the flow of CIP return stream 64B from first RO concentrate pipework <NUM>, second RO concentrate pipework <NUM>, and NF concentrate pipework <NUM> to CIP assembly <NUM>. In some embodiments, the valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 333A, 33B, <NUM>, and <NUM> of membrane skid <NUM> are controlled remotely by the control system <NUM> of integrated system <NUM>.

As shown particularly in <FIG>, in this embodiment, support structure <NUM> of membrane skid <NUM> generally includes a rectangular upper frame <NUM> positioned at the top 306A of membrane skid <NUM>, a rectangular lower frame <NUM> positioned at the base 306B of membrane skid <NUM>, a plurality of vertical support members <NUM>, a first or upper support rack 390A, a plurality of second or intermediate support racks 390B, and a plurality of third or lower support racks 390C. Upper frame <NUM> include a laterally extending central support member <NUM> disposed equidistantly between the front and rear ends 302A, 302B of membrane skid <NUM>. Lower frame <NUM> also includes a plurality of laterally extending support members <NUM> spaced between the ends 302A, 302B of membrane skid <NUM>. Lower frame <NUM> further includes a longitudinally extending support member <NUM> disposed equidistantly between lateral sides <NUM> and extending between the ends 302A, 302B of membrane skid <NUM>.

In this embodiment, support structure <NUM> includes four vertical support members <NUM>, two vertical support members <NUM> disposed along each of the lateral sides <NUM> of membrane skid <NUM>. Additionally, a first pair of vertical support members <NUM> is positioned proximal to the first end 302A of membrane skid <NUM>, while a second pair of vertical support members <NUM> is positioned proximal to the second end 302B of membrane skid <NUM>. Intermediate support racks 390B are disposed vertically between upper support rack 390A and lower support racks 390C, where upper support rack 390A is positioned proximal to upper frame <NUM> and a lowermost of the lower support racks 390C is positioned proximal to the lower frame <NUM> of support structure <NUM>. In this embodiment, support structure <NUM> includes a pair of elevated horizontal support members <NUM>, each elevated horizontal support member <NUM> extending between ends 302A, 302B and coupled to a pair of vertical support members <NUM>. A plurality of crossbraces <NUM> extend diagonally between both upper frame <NUM> and elevated horizontal support members <NUM>, and between elevated horizontal support members <NUM> and lower frame <NUM>.

Support structure <NUM> additionally includes a pair of vertical support <NUM> positioned proximal to, but spaced from the ends 302A, 302B of membrane skid <NUM>, each vertical support <NUM> positioned equidistantly between the lateral sides <NUM> of membrane skid <NUM>. Each vertical support <NUM> extends vertically between the upper frame <NUM> and the lower frame <NUM> of support structure <NUM>, where each support rack 390A, 390B, and 390C extends laterally between one of the lateral sides <NUM> of membrane skid <NUM> and one of the vertical supports <NUM>. In this embodiment, support frames <NUM>, <NUM>, and members <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> each comprise metallic (e.g., carbon steel, alloy steel, etc.) I-beams; however, in other embodiments, support frames <NUM>, <NUM>, and members <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may comprise varying cross-sectional shapes and materials.

In the configuration of membrane skid <NUM> described above, headers 312A, 312B, 320A, 320B, 330A and 300B, and pipeworks <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are each directly supported by the lower frame <NUM> of support structure <NUM>.

Particularly, only the racks 310A, 310B, and <NUM> of RO membrane separation units <NUM> and NF filtration units <NUM>, respectively, are directly supported by a support member of support structure <NUM> that is elevated from the lower frame <NUM>. Particularly, NF filtration units <NUM> contact, and are supported by upper support rack 390A; the upper rack 310B of RO membrane separation units <NUM> contact, and are supported by intermediate support racks 390B; and the lower rack 310A of RO membrane separation units <NUM> contact, and are supported by lower support racks 390C. Thus, the upper frame <NUM> of support structure <NUM> is not required to support the weight of headers 312A, 312B, 320A, 320B, 330A and 300B, and pipeworks <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of membrane skid <NUM>. By supporting the components of membrane skid <NUM> at the lower frame <NUM> thereof rather than at the upper frame <NUM>, the total weight of support structure <NUM> may be minimized given that the loads supported by upper frame <NUM> and vertical support members <NUM> may, in-turn, be minimized.

Additionally, valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 333A, 333B, <NUM>, and <NUM> of membrane skid <NUM> are each positioned proximal to lower frame <NUM> and distal to upper frame <NUM> of support structure <NUM>. In other words, valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 333A, 333B, <NUM>, and <NUM> are positioned nearer to the lower frame <NUM> than to the upper frame <NUM> of support structure <NUM>. With valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 333A, 333B, <NUM>, and <NUM> of membrane skid <NUM> positioned proximal lower frame <NUM>, the distance between the deck 35B and a center of mass of the membrane skid <NUM> is minimized, thereby reducing the vertical distance Dp between the sea floor <NUM> and the center of mass <NUM> of the desalination platform <NUM>. With one or more embodiments, because the loads supported by upper frame <NUM> and vertical support members <NUM> are minimized, upper frame <NUM> and vertical support members <NUM> can be formed using lighter-weight materials. With one or more embodiments, the center of mass of membrane skid <NUM> is in the lower half of membrane skid <NUM>. Further, given that valves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 333A, 333B, <NUM>, and <NUM> of membrane skid <NUM> are positioned proximal to lower frame <NUM>, the fluid conduits used to convey UF filtrate stream <NUM>, RO reject stream 49A (comprising second RO concentrate stream 49A and NF reject stream 49B), and CIP streams 64A, 64B may each be supported by, and positioned proximal to, deck 35B (rather than being suspended from above in a position distal to deck 35B), further reducing the vertical distance Dp between the sea floor <NUM> and the center of mass <NUM> of the desalination platform <NUM>.

Claim 1:
A desalination system (<NUM>), comprising:
a desalination platform (<NUM>);
a first skid (<NUM>, <NUM>) disposed on a first deck (35A) of the desalination platform (<NUM>), the first skid (<NUM>, <NUM>) comprising at least one of a first filtration unit (<NUM>) configured to produce a first filtrate stream (<NUM>), and a first permeate unit (<NUM>) configured to produce a first permeate stream (<NUM>);
a first interconnecting pipework (<NUM>) coupled to the first skid (<NUM>, <NUM>); and
a first pipework support (<NUM>) disposed on the first deck (35A), wherein the first interconnecting pipework (<NUM>) is disposed on the first pipework support (<NUM>); a first support structure (<NUM>, <NUM>) comprising a first upper frame (<NUM>, <NUM>) positioned at a top (106A, 306A) of the first skid (<NUM>, <NUM>) and a first lower frame (<NUM>, <NUM>) positioned at a base (106B, 306B) of the first skid (<NUM>, <NUM>);
a first inlet pipework (<NUM>, <NUM>) coupled between a first inlet valve (<NUM>, <NUM>) and the at least one of the first filtration unit (<NUM>) and the first permeate unit (<NUM>), wherein the at least one of the first filtration unit (<NUM>) and the first permeate unit (<NUM>) is supported by the first support structure (<NUM>, <NUM>), wherein the at least one of the first filtration unit (<NUM>) and the first permeate unit (<NUM>) is configured to produce the first filtrate stream (<NUM>) or the first permeate stream (<NUM>), respectively, from an inlet stream supplied to the first inlet valve (<NUM>, <NUM>); and
a first discharge pipework (<NUM>, <NUM>) coupled between the at least one of the first filtration unit (<NUM>) and the first permeate unit (<NUM>) and a first discharge valve (<NUM>, <NUM>); and
wherein the first inlet valve (<NUM>, <NUM>) and the first discharge valve (<NUM>, <NUM>) are each directly supported by the first lower frame (<NUM>, <NUM>) of the first support structure (<NUM>, <NUM>).