Subsurface multi-stage oxygenation system to support net-pen aquaculture.

Abstract

The multi-stage oxygenator includes an immersed fluid-tight pressure vessel having a first section, a second section, and a third section. A baffle divides the second section into compartments, and a water delivery mechanism delivers water through the first section to the second section. A junction between the first and second sections delivers water as water jets or droplets to the compartment to create a flooded zone. A gas delivery mechanism delivers oxygenated gas to the compartment to create a gas void between the flooded zone and the first section into which the water jets or droplets fall. A gas connection through the baffle allows gas from a compartment to create another gas void in the subsequent compartment in series with it. A gas release device maintains the gas void by releasing gas from the last compartment. A third section connects the compartments and water from the flooded zone mixes to produce output treated water.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is related to and claims the benefit of priority to U.S. Application No. 63 / 308,742, entitled “SUB-SURFACE MULTI-STAGE OXYGENATION SUPPORTING NET PEN AQUACULTURE,” filed February 10, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] The aquaculture industry is growing rapidly in response to a global demand for seafood that exceeds the supply provided by wild fish stocks. Intensification of production methods such as net-pen technology is attractive given the reduced reliance on freshwater resources. Production capacity is most often limited by limited supplies of dissolved oxygen (DO, mg / l), as well as the accumulation of fish metabolic products, including dissolved carbon dioxide (DC, mg / l). Water quality limitations correlate with insufficient water exchange during periods of increased biomass or stress during disease treatment and harvesting operations. DO supplementation can be achieved by contacting the water with oxygen-enriched gas in devices designed to provide a large air-liquid interfacial area. These systems offer a unique ability to supersaturate water with DO, greatly reducing the amount of water that needs to be treated to meet a given oxygen demand. The reduction in water flow rate lowers production costs by minimizing the energy and capital inputs associated with oxygen addition. Unlike air-contacting systems, oxygen absorbers provide stripping of dissolved nitrogen (DN, mg / l) to below saturation levels for the purpose of controlling aerobatic diseases. The degree of DN stripping or DO absorption is easily adjusted by adjusting the gas flow rate and / or system operating pressure. This flexibility in performance provides additional savings in water treatment costs. There is great value in commercial oxygen purchased in bulk liquid or produced on-site using a pressure swing absorption system. Therefore, the design of the oxygenator must be optimized to provide a reasonable energy input (TE, kgO 2The oxygenator must provide high oxygen utilization efficiency (AE,%) at 1000 kW / kW-hr. Furthermore, since the oxygenator is used in fish farming in a life support role, the design employed must reduce the risk of electrical or mechanical failure. This is important as the challenges regarding oxygen management increase with advances in enclosed and semi-enclosed fish pen technology that help reduce the inhalation of near-surface water into the fish habitat. Hence, there is a need for an efficient oxygenation system applicable to enclosed and semi-enclosed fish pen systems that maximizes the benefits of inhalation water flow.

[0003] Furthermore, the high solubility of carbon dioxide precludes significant desorption in commercial oxygen absorbers. This characteristic limits the application of commercial oxygen absorbers in aquaculture, despite their ability to increase the acceptable fish loading. DC is typically removed by air stripping, given the need to apply very high gas-to-liquid ratios. Forced air exchange in such air stripping systems requires significant energy input for both air compression and humidity, as well as temperature and carbon dioxide control within the enclosed aquaculture facility. Separate pumping requirements and / or energy are also required for the development of additional gas-liquid interface area required for gas transfer.

[0004] Common systems / methods for oxygenation and / or DC stripping in aquaculture include U-tubes, downflow bubble contactors, sidestream oxygen injection, closed spray towers, closed packed columns, closed surface agitation, unpacked (standard) multi-stage lower head oxygenators (LHO), base reagent addition, and diffusion oxygenation, all of which have their own problems that limit their application in aquaculture. These problems include sensitivity to biofouling (e.g., packed columns), excessive maintenance requirements (e.g., diffusion oxygenation), increased energy requirements (e.g., surface agitators), high pumping costs (e.g., sidestream oxygenation), limited increase in change in DO throughout the system (e.g., LHO), elevated pH levels (e.g., base reagent addition), and capital cost requirements that are dependent on local geology, for example, for the need for deep boreholes (e.g., U-tube oxygenation).

[0005] DC must usually be considered in the design of intensive culture systems given the increased respiration rates of fish and microorganisms, as well as the need to maintain DC below established standards to prevent stress, nephrocalcinosis, and hypoxia. As mentioned before, desorption of DC in commercial oxygen absorbers is severely limited given the high solubility of this gas species and, inevitably, the use of oxygen feeds that represent only 0.5-3% of the water feed. DC is typically removed in a separate treatment step by air stripping. This process requires significant energy inputs for forced air movement, air heating in cold climates, and water pumping. Moreover, this air stripping drives the DN towards air saturation concentrations, forcing the use of absorber operating conditions that increase the cost of oxygen addition in recirculating aquaculture systems (RAS). In other words, as the DN rises, the AE decreases.

[0006] The foregoing "Background" discussion is intended to generally present the context of the present disclosure. The inventors' work, to the extent described in this Background section, as well as aspects described that may not qualify as prior art at the time of filing, are not admitted expressly or impliedly as prior art to the present disclosure. Summary of the Invention

[0007] In one embodiment, the subsurface multi-stage oxygenator system includes one or more chambers configured to be submerged in or near an aquaculture system enclosure, each of the one or more chambers having an open top. The system also includes one or more distribution mechanisms, each of which is disposed on the open top of a corresponding one of the one or more chambers and configured to distribute liquid provided to the one or more distribution mechanisms in jets or droplets to the one or more chambers. The system further includes a gas input to each of the one or more chambers, a gas input configured to introduce gas into the respective chamber, and a gas output from each of the one or more chambers, the gas output configured to release gas from the respective chamber. The jets or droplets enter liquid held within each of the one or more chambers at one or more regions disposed directly below the one or more distribution mechanisms to generate one or more circulating cells of gas bubbles.

[0008] In one embodiment, a method of performing high efficiency oxygenation uses a subsurface multi-stage oxygenator system including one or more chambers configured to be submerged in or near an aquaculture system enclosure, one or more distribution mechanisms disposed on the one or more corresponding chambers, and a gas input to each of the one or more chambers. The method includes providing a liquid to the one or more distribution mechanisms such that the liquid is distributed in jets to the one or more chambers, and providing a gas through the gas input to each of the one or more chambers such that the gas flows above the liquid stored in the one or more chambers and through a head space portion of each of the one or more chambers. The jets contact the gas in the head space portion of the respective chambers and then enter the liquid held in the respective chambers to generate one or more circulating cells of gas bubbles within the liquid held in the respective chambers.

[0009] In an exemplary embodiment, a multi-stage oxygenator system includes a fluid-tight pressure vessel for use in a submerged state, the pressure vessel including a first section, a second section, and a third section. At least one baffle divides the second section of the pressure vessel into two or more compartments. A water delivery mechanism delivers water to the second section of the pressure vessel through the first section of the pressure vessel. The first section of the pressure vessel includes a junction between the first section of the pressure vessel and the second section of the pressure vessel. The junction delivers water as water jets or droplets to the two or more compartments in the second section of the pressure vessel to create a flooded zone in the two or more compartments. The flooded zone is filled with water. A gas delivery mechanism delivers gas to a first of the two or more compartments to create a first gas void in the first of the two or more compartments. The gas includes oxygen. A first gas gap is disposed between the first section of the pressure vessel and the flooded zone of the first of the two or more compartments, and water jets or droplets fall through the first gas gap onto a first free surface of the flooded zone of the first of the two or more compartments. A gas connection through at least one baffle allows gas to travel from at least a first of the compartments to at least a second subsequent compartment in series therewith. A gas release device on a side of the second section of the pressure vessel releases gas from the last of the compartments in series. The gas release device is positioned at a designated location within the compartment to maintain the first gas gap and the second gas gap at a predetermined volume. A discharge port in a third section of the pressure vessel outputs treated water from the pressure vessel. The third section of the pressure vessel connects two or more compartments of the second section to allow water from the flooded zones of the two or more compartments to mix to produce treated water. The multi-stage oxygenation system is fixed and stabilized at a predetermined depth.

[0010] In an exemplary embodiment, the junction between the first and second sections of the pressure vessel includes a plate having a plurality of openings for forming the water jets.

[0011] In an exemplary embodiment, the water delivery mechanism includes a pipe disposed at a center of the pressure vessel and extending through the first, second, and third sections. A manifold is connected to the pipe and to a junction between the first and second sections of the pressure vessel. The pipe delivers water to the manifold, which delivers water to each of the two or more compartments via the junction between the first and second sections of the pressure vessel. At least one baffle is attached to the pipe and to an interior wall of the pressure vessel to create the two or more compartments within the second section of the pressure vessel.

[0012] In an exemplary embodiment, the first section of the pressure vessel includes a chamber that can be flooded with water by a water delivery mechanism. The junction between the first and second sections of the pressure vessel includes a plate having one of a plurality of openings for forming water jets to deliver water to two or more compartments at a predetermined water pressure, or at least one nozzle for forming water droplets to deliver water to two or more compartments at a predetermined water pressure.

[0013] In an exemplary embodiment, the gas release device includes one of a float valve or an off-gas port. The off-gas port includes a connector connected to the pressure vessel, a right angle coupling connected to the connector, and a tube connected to the right angle coupling. An open end of the tube defines a location of a free surface of the flooded zone of the two or more compartments.

[0014] In an exemplary embodiment, the water outlet port is coupled to a pressure control valve that maintains the pressure vessel at a predetermined pressure.

[0015] In an exemplary embodiment, the predetermined pressure regulates oxygen exchange from the gas to the water and promotes nitrogen removal from the water, and the predetermined pressure preferably simulates a depth of 100 feet.

[0016] In an exemplary embodiment, the reactor off-gas containing oxygen and nitrogen is vented from all of the two or more compartments of the second section of the pressure vessel via a gas release valve.

[0017] In an exemplary embodiment, the pressure vessel is secured and stabilized in place via at least one of a ballast and mooring structure or a pipe riser configured to deliver water to a water delivery mechanism.

[0018] In an exemplary embodiment, the multi-stage oxygenator system further includes a submersible pump attached to the pipe riser for pumping water through the pipe riser and into the water delivery mechanism, the pump forming at least a portion of the ballast that stabilizes the multi-stage oxygenator.

[0019] In an exemplary embodiment, water jets or droplets impact a first free surface and a second free surface of the two or more compartments to form a bubble entrainment zone in each of the two or more compartments. A quiescent zone is disposed between the bubble entrainment zone and a third section of the pressure vessel in each of the two or more compartments. Air bubbles in the water within the quiescent zone bind to and rise into a respective one of the first free surface and the second free surface and subsequently into a respective one of the first gas void and the second gas void.

[0020] In an exemplary embodiment, the multi-stage oxygenator system further includes a pump coupled to the water delivery mechanism for pumping water from a water source to the water delivery mechanism. A screen is coupled to the inlet of the pump for screening solids from the water. The water source is fresh water or salt water.

[0021] In an exemplary embodiment, the multi-stage oxygenator system further includes at least a second baffle oriented perpendicular to the at least one baffle that separates downwardly flowing gas bubbles in the flooded zone of at least one of the two or more compartments from upwardly flowing gas bubbles in at least one of the two or more compartments. The second baffle is attached to an interior wall of the pressure vessel.

[0022] In an exemplary embodiment, the multi-stage oxygenator system further includes a vent for venting gas from the pressure vessel during at least one of installation, maintenance, and removal of the pressure vessel.

[0023] In an exemplary embodiment, the water delivery mechanism includes at least one distribution plate with a predetermined number of orifices distributed within one or more zones of the at least one distribution plate and no orifices within at least one remaining zone of the at least one distribution plate. Water flows through the orifices of the at least one distribution plate into two or more compartments. The orifices in the at least one distribution plate are arranged in a double row to form orifice groups separated by gaps that do not include an orifice. The orifice groups are arranged to cover a predetermined amount of linear area based on hydraulic loading corresponding to a given application of the multi-stage oxygenator system.

[0024] A more complete appreciation of the present disclosure, and many of the attendant advantages thereof, will be readily obtained as the same becomes better understood by considering the following detailed description in connection with the accompanying drawings, in which: [Brief description of the drawings]

[0025] [Figure 1a] 1 shows a top view of a standard liquid distribution plate and a side view of a single chamber depicting bulk flow using an associated distribution plate. [Figure 1b] 1 shows a top view of a side stream distribution plate and a side view of a single chamber depicting bulk flow using a side stream distribution plate according to an exemplary embodiment of the present disclosure. [Figure 2a] FIG. 1 illustrates a top view of a sidestream distribution plate installed on a six-chamber oxygenation system according to an exemplary embodiment of the present disclosure. [Figure 2b] FIG. 1 illustrates a top view of head space gas movement through a six chamber oxygenation system according to an exemplary embodiment of the present disclosure. [Figure 2c]FIG. 1 shows a side view of an oxygenation system having two reverse circulation cells within the bubble entrainment zone for each of six chambers according to an exemplary embodiment of the present disclosure. [Diagram 3] FIG. 1 shows a side view of a single chamber using a side stream distribution plate and vertical and horizontal baffles to promote uniform bubble release across the quiescent zone width according to an exemplary embodiment of the present disclosure. [Figure 4] 1 shows a top view of a distribution plate having two sets of orifices and a side view of a chamber using the distribution plate to generate jets along two edges of the chamber wall according to an exemplary embodiment of the present disclosure. [Diagram 5] FIG. 1 shows a top view of a distribution plate with four sets of orifices and three solid areas between the orifices, and a side view of a chamber using the distribution plate to generate two sets of jets along the two edges of the chamber wall and two sets of jets along a vertical baffle, according to an exemplary embodiment of the present disclosure. [Figure 6a] 1 shows a top view of head space gas movement through a circular oxygenation system having six chambers and a top view of a distribution plate portion that can be used for each chamber according to an exemplary embodiment of the present disclosure. [Figure 6b] FIG. 1 shows a top view of head space gas movement through a circular oxygenation system having six chambers and a top view of a distribution plate where each chamber can be used to generate a reverse circulation cell according to an exemplary embodiment of the present disclosure. [Figure 7a] 1 shows a top view of head space gas movement through a circular oxygenation system having ten chambers according to an exemplary embodiment of the present disclosure, and a top view of a distribution plate that can be used with the system. [Figure 7b] 1 shows a top view of head space gas movement through a circular oxygenation system having six chambers according to an exemplary embodiment of the present disclosure, and a top view of a distribution plate that can be used with the system. [Figure 8a] 1 illustrates modification of a side stream distribution plate for salt water treatment according to an exemplary embodiment of the present disclosure. [Figure 8b] 14 illustrates another side stream distribution plate modification for salt water treatment according to an exemplary embodiment of the present disclosure. [Figure 8c] 1 illustrates modification of a side stream distribution plate for salt water treatment according to an exemplary embodiment of the present disclosure. [Figure 9] 1 illustrates a flow diagram of a method according to an exemplary embodiment of the present disclosure. [Figure 10a] 1 shows a top view of a distribution plate having two sets of orifices and a side view of a chamber using the distribution plate to perform stripping using scrubbing inserts according to an exemplary embodiment of the present disclosure. [Figure 10b] 1 shows a top view of a distribution plate having two sets of orifices and a side view of a chamber using the distribution plate to perform stripping using scrubbing inserts according to an exemplary embodiment of the present disclosure. [Figure 10c] 1 shows a top view of a distribution plate having two sets of orifices and a side view of a chamber using the distribution plate to perform stripping using scrubbing inserts according to an exemplary embodiment of the present disclosure. [Figure 11] 1 illustrates a flow diagram of a method according to an exemplary embodiment of the present disclosure. [Figure 12] FIG. 1 shows a side view of a subsurface multi-stage oxygenation system suspended at a constant depth and using side-flow water distribution plates. [Figure 13a] FIG. 13 shows a top view of gas flow movement within the multi-stage oxygenation system illustrated in FIG. [Figure 13b] FIG. 13 shows a side view of gas flow movement within the multi-stage oxygenation system illustrated in FIG. [Figure 14] FIG. 1 shows a side view of a subsurface multi-stage oxygenation system that is suspended at a constant depth and allows for coupling with an existing semi-contained net pen suction line. [Figure 15] FIG. 1 shows a side view of a subsurface multi-stage oxygenation system suspended at a constant depth and allowing the existing net-pen pumping action to draw water into the system without an auxiliary axial pump. [Figure 16] FIG. 1 shows a side view of a subsurface multi-stage oxygenation system that is suspended at a constant depth, either fixed or tethered, and allows for hydrostatic pressurization via connection to a deep RAS fish tank. [Figure 17] FIG. 1 shows a side view of a subsurface multi-stage oxygenation system suspended at a constant depth, either fixed or tethered, and by using spray nozzles. [Figure 18] FIG. 18 shows a top view of gas flow movement within the spray nozzle-based subsurface multi-stage oxygenation system illustrated in FIG. 17. [Figure 19] FIG. 1 shows a side view of a subsurface multi-stage oxygenation system suspended at a constant depth and using spray nozzles. [Figure 20] 1 illustrates a perspective view of the installation of a subsurface multi-stage oxygenation system for a fish pen, according to an exemplary embodiment of the present disclosure. [Figure 21] 1 illustrates another perspective view of the installation of a subsurface multi-stage oxygenation system for a fish pen according to an exemplary embodiment of the present disclosure. [Figure 22] 1 illustrates a two-stage oxygenator with backpressure control according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The terms "a" or "an," as used herein, are defined as one or more than one. The term "plurality," as used herein, is defined as two or more than two. The term "another," as used herein, is defined as at least a second or more. The terms "including" and / or "having," as used herein, are defined as comprising (i.e., open language). References throughout this document to "one embodiment," "a particular embodiment," "embodiment," "implementation," "example," or similar terms mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments, without limitation.

[0027] The present disclosure is directed to a new submerged multi-stage reactor (oxygenator) design that takes advantage of the positive effects of hydrostatic pressure on gas transport. This new design improves TE and AE as well as reduces the required reactor volume. The reactor described operates submerged with the gas-liquid interface area provided by a conventional or sidestream water distribution plate that can be modified to reduce saltwater hydraulic load limits or a bank of full cone type spray nozzles when bio-fouling rates are high. As can be appreciated, other spray nozzles besides full cone type spray nozzles can be used without departing from the scope of the present disclosure.

[0028] The systems and methods described herein allow for economical and effective treatment of submersible culture water with commercially available oxygen for oxygenation, as well as nitrogen and / or carbon dioxide removal, improving production capacity while simultaneously reducing the likelihood of air bubble disease.

[0029] The advantage of the sidestream distribution plate design described herein is its unique ability to enhance gas transfer for a selected spray drop height or reduce the spray drop height required for a target DO replenishment rate. Either response acts to reduce water treatment costs. Furthermore, the new plate design opens up the possibility of modifying the chamber with minimal effort to allow for simultaneous DC stripping. The latter modification can reduce the energy costs associated with DC control. Although the focus of this application is on aquatic culture applications, the advantages of the described oxygen transfer system will extend to other oxygenation applications, such as municipal or industrial wastewater treatment.

[0030] This disclosure describes a gas-liquid chamber feed water distribution plate and structure designed to extend standard perforated plate performance without additional energy input (pumping). The plate design and unique application method described herein provides a localized increase in momentum transfer, which enhances shear forces and promotes the development of a well-defined circulation cell or cells within the chamber, causing (1) accelerated vertical displacement of the bubble cloud, (2) an increase in penetration depth (Hp), (3) rising of the bubbles throughout the regions of the pool that do not receive the feed water jet, and (4) enhanced re-exposure of the water present within the chamber to the action of the jet through enhanced mixing. Physical changes 1-4 combine to increase the selected spray drop height (L O ) or L for the desired DO replenishment rate O This results in reduced requirements.

[0031] Subsurface operation can dramatically increase oxygenation performance through hydrostatic effects, including increases in DO out, oxygen transfer rate, AE and TE. In an embodiment, the reactor is submerged at a depth that provides a local hydrostatic pressure of at least 100 mmHg above the local air pressure within the submerged reactor assembly. This reactor type takes advantage of deep water available in net pen and semi-contained net pen applications and can utilize existing suction lines / bulk flow to increase water exchange rates within the culture unit, dilute treated water and transport to the enclosure. In one embodiment, as illustrated in FIG. 15, the existing net pen pump is used to induce flow through the reactor without the need for an additional axial pump step, thus reducing capital requirements. The impact of wave action on reactor performance can be minimized by creating a shock absorbing effect on the supporting cabling through the use of flexible rods, springs and gas pistons at the attachment points of the cabling on the reactor or on the net pen support structure.

[0032] The distribution plate described herein can free up space in the head space region of the chamber to perform DC stripping. Conventional spray tower oxygen absorbers for simultaneous DC stripping avoid the problem of an air stripping step in associated systems by allowing the DN in the RAS to fall below saturation concentrations, thereby reducing oxygen supply requirements and lowering the total dissolved gas pressure below levels that would result in air bubble disease. In operation, the DC desorption is performed by directing head space gases (e.g., O 2 ) from the spray tower through a sealed packed bed scrubber that receives a sodium hydroxide (NaOH) solution. 2 , N 2 , CO 2 This was achieved by inducing the selective removal of DC from the gas stream by chemical reaction to produce the product Na 2 CO 3 CO was formed. 2 Although it is sparse, there is still 2 The CO-rich scrubber off-gas is then 2 Further removal of and O 2The make-up NaOH was then redirected through a spray tower for absorption of NaOH. As directed by the pH-based control loop, the make-up NaOH was fed to a scrubbing solution recirculation sump. The spent NaOH solution collected as the overflow was then diluted with relatively inexpensive hydrated lime (Ca(OH) 2 The scrubber was regenerated for reuse in a batch process using scrubber irrigation. The scrubber irrigation rate represented a fraction of the spray tower water flow rate. Although effective, this modification required two sealed gas transfer units coupled with a blower assisted gas recirculation loop. This requirement can be dropped when using the new distribution plate design according to the present disclosure, since according to one embodiment, the new distribution plate design frees up about 75% of the head space volume available in the gas-liquid contact chamber. In one embodiment of the present disclosure, the scrubbing unit is nested within the head space of the chamber and positioned directly adjacent to the feed water jet. This allows for the addition of NaOH or other CO 2 Due to reaction with scrubbing reagents (e.g., hydrated lime), CO 2 The present invention allows for the diffusion and / or redirection of associated gases rich in scrubber components.

[0033] In the exemplary application described herein, no packing is present in the individual chambers and therefore only the water jet developed by the water distribution plate is relied upon to provide the necessary gas-liquid interface area. The latter is provided by the jet surface as well as the impact of the jet on the free surface of the water in the chamber. According to one embodiment, gas entrainment occurs at the impact site with air bubbles being forced to a depth of up to 0.5m under turbulent conditions. The air bubble size, entrainment depth and resulting mass transfer potential are related to the salinity of the water above the feedwater distribution plate, jet diameter, jet velocity, spray drop height, temperature and surface hydraulic loading. The surface hydraulic loading on the distribution plate in freshwater applications is about 68kg / m 2 / sec, which correlates to a downflow water velocity of 6.8 cm / sec in the quiescent zone of the gas-liquid contact chamber. Operating above this critical velocity, at a quiescent zone depth of approximately 46 cm, can cause entrained gas to sweep out the discharge end of the gas-liquid chamber, wasting oxygen-enriched gas and thus reducing AE.

[0034] Standard gas-liquid contacting chambers rely on water jets developed by perforated water distribution plates without packing to provide the gas-liquid interfacial area required for gas transport. Previously used plates have jet locations uniformly located over the cross section of the chamber. This disclosure describes a more efficient distribution plate design that concentrates the jet action over a limited area of ​​the chamber cross section. Here, the number of jets is fixed and equal to the standard plate requirement, but the spacing between the jets is reduced by up to 80%. Furthermore, the generated jets can be strategically positioned along or at one side of a standard rectangular gas-liquid contacting chamber, at a certain depth, to induce the water and entrained gas bubbles to flow parallel to the free surface of the chamber before wall effects rise towards the head space region of the chamber. The result is a high hydraulic load (e.g., 68 kg / m 2 While complying with established standards for dissolved gas deficiency (C / sec), this will increase local turbulence and gas retention. The turbulence and gas retention will then increase the dissolved gas deficit (C * The overall mass transfer coefficient (K -C) governs the gas transfer rate. L a) In differential form, the relationship can be expressed as

number

[0035] Coefficient K L a reflects the conditions that exist in a particular gas-liquid contact system. This factor is determined by the ratio of two factors (D / L f ) and (A f / Vol), D is the diffusion coefficient, and L f is the liquid film thickness, and A fis the area through which the gas diffuses per unit volume (Vol) of water being treated. K L The value of a is expressed by the following equation: f and A f increases with temperature (°C), taking into account the effect of viscosity on

number

[0036] Each gas species in the contact system is L While each has a unique value of a, the relative values ​​for a particular gas pair are inversely proportional to their molecular diameters.

number

[0037] Equation (3) provides a convenient means to model multicomponent gas transport processes such as the addition of DO, stripping of DN and DC occurring simultaneously in a pure oxygen absorber. The dissolved gas deficit (C * -C) is manipulated within the confines of the gas-tight chamber by increasing the mole fraction of oxygen, X, above that of the local atmosphere (0.20946) with an oxygen supply. That is, the saturation concentration of the gas in solution (C * ) is related to Henry's law by the gas phase (P i ), the liquid temperature, and its partial pressure in the liquid composition. In formula form it is:

number

[0038] where B is the Bunsen solubility coefficient, K is the ratio of molecular weight to molecular volume, and P H2O is the water vapor pressure. i ) is calculated according to Dalton's law as follows: T ) and the gas phase mole fraction X. P i =(P T )(X) (5)

[0039] In the exemplary subsurface oxygenator described herein, C * O2 is the increase in hydrostatic pressure at a certain depth, and X O2 Both factors work together to accelerate the gas transfer rate, thus minimizing the size of the equipment and providing effluent DO levels above local air saturation concentrations. Neglecting the effects of trace gas species, X O2 The increase in N2 =1-X O2 According to the DN C * In many cases, the resulting negative dissolved gas deficit provides DN stripping. However, the DN stripping potential decreases as the hydrostatic pressure in the reactor increases. Given the possibility of bubble disease, the net effect of the changes in DO and DN, following dilution, preferably does not result in exposing the fish to a total dissolved gas pressure (TGP) that exceeds the local atmospheric pressure (Bp), i.e., ΔP is preferably equal to or less than BP, where ΔP=TGP-BP. TGP represents the sum of the dissolved gas tensions (GT, mmHg) for all gas species (i) present. GT i is the product (C i )(760 / 1000K i )(B i In the exemplary subsurface oxygenator described herein, O 2 C * At a certain depth, through the increase in hydrostatic pressure, as well as X O2 Both factors work together to accelerate oxygen transport. Stripping of DN increases the N 2 into the head space (gas) of the reactor chamber to obtain the mole fraction of oxygen, X O2 , O 2 C *, and thus the dissolved gas deficit that governs the gas transfer rate (Eq. (1)). The gas phase composition in the head space in each chamber is homogeneous given the mixing forces of the jets and sprays, and the very low working gas to liquid feed ratio. Under these conditions, multi-stage is applied as a physical method to increase the average dissolved gas deficit above that provided by a single-stage reactor sharing a homogeneous gas phase. In multi-stage, X O2 The reduced DO feed gas is directed through adjacent gas-liquid contact chambers that operate in series with the gas flow but in parallel with the liquid feed. As it progresses towards the gas discharge port in the final stage, the continued re-exposure of the head space gas to the lower DO concentration in the liquid feed provides significant improvements in oxygen transfer rate, AE and TE. O2 The gradual decrease in DO changes the specific discharge in the chamber from a relatively high value in the first stage to a relatively low value in the final stage. The exemplary subsurface oxygenator described herein uses a blending zone below the chamber boundary in the reactor to force mixing and therefore provide a homogenous DO concentration in the discharge of the reactor.

[0040] Liquid jets and sprays are L To maintain an acceptable value of V, the subsurface oxygenator must provide the necessary gas-liquid interfacial area in both the head space (gas void) and the entrainment zone (Eq. (1)). Air entrainment in an incoming liquid jet increases with the velocity-dependent Froude number FR, for example: FR=V 2 / (g*d), where V is the velocity, g is gravity, and d is the nozzle diameter. The velocity of the jet exiting the progressive distribution plate (V o ) is relatively low given the need to minimize pressure drop by design. However, the jet velocity at the point of impact is V, as described by the following relationship: o and the velocity gain from gravity. Vj=(V o 2 +2gL) 0.5where L is the elevation change from the nozzle discharge to the free surface receiving the jet. The effect of gravity on Vj is significant. For example, at 15.2 cmH across the orifice 2 With a pressure drop of O, V o is 1.38 m / sec, but when L is only 0.609 m, Vj increases by 2.64 to 3.65 m / sec. L The net power of the jet (Nj) propelling a increases as the square of Vj for a given volumetric flow rate Q: Nj=0.5QpVj 2 where Nj is in watts and p is the liquid density.

[0041] K L The positive effect of Nj on a is due to enhanced momentum transfer from the jet, which increases the volume and penetration depth of the entrained gas, and turbulence / shear forces, which act to reduce the bubble diameter and associated liquid film thickness (L f , Equation 1). Small bubbles not only have a larger surface area (A) but also a longer upward exposure in the receiving pool than larger bubbles. Nj for freshwater applications is (1) 68 kg / m3 designed to eliminate bubble carryover in the effluent. 2 / sec hydraulic loading rate criteria, and (2) the need to minimize feedwater head requirements at the distribution plate. A more efficient distribution plate design is needed that provides the described benefits of increasing Nj without exceeding limits 1 and 2 above. The present disclosure addresses this need by manipulating the plate hole schedule of orifices and utilizing unique geometries of individual gas-liquid contacting chambers.

[0042] Referring now to the drawings, FIG. 1a illustrates a standard distribution plate 201 used in a chamber 200, the width across the shorter dimension of the standard chamber 200 being D 11a. The standard distribution plate 201 includes an area (represented by hash lines) with orifices 108 distributed throughout. When liquid 134 is contained in the trough 132, it flows through the orifices 108 and forms jets 114. The jets 114 fall through a spray drop zone or gas void 118 that contains gas (e.g., oxygen) that can be input / output using gas ports 112. When the jets 114 contact the free water surface 116, they penetrate the water to a certain depth and create a bubble entrainment zone 120. Also shown in FIG. 1a are the quiescent zone 124, discharge slot 126, and support legs 128, which are not used in subsurface oxygenator applications. While the present exemplary embodiment includes the trough 132, other system configurations may use a different vessel in place of the trough 132, such as a vacuum chamber, or an airtight pressure vessel in the case of a submerged reactor, etc. Additionally, the discharge slots 126 are optional. For example, if the LHO chamber 200 is under vacuum, the discharge slot 126 can be removed. Exemplary embodiments of a vacuum degasser or medium pressure oxygenator are discussed in more detail below.

[0043] In an example using practical values, a standard distribution plate 201 has a uniform distribution of 29 jet orifices 108 (d=9.53 mm) over a single LHO chamber 200 with a cross-section measuring 12.7 cm×35.6 cm. In use, jet impingement provides a point source of entrained head space gas. Bubbles formed in the bubble entrainment zone 120 are carried vertically downstream while diffusing radially. The radial expansion of the bubble cloud with depth reduces local turbulence and downward velocity, allowing the bubbles to escape and rise in the open areas between adjacent jets. Thus, the bubble entrainment zone 120 is dynamic with gas moving in both vertical directions while the bulk liquid flows steadily towards the lower discharge end of the chamber with some dispersion. For Q=170.3 l / min, Q / A ジェット Based on V ois 1.37 m / sec. In this example, L of 0.308 mVj rises to 2.803 m / sec, providing a total Nj of 11 watts of jet power. The corresponding force applied per unit cross section is 243.4 Watts / m 2 It is.

[0044] FIG. 1b illustrates a sidestream distribution plate 202 used in a chamber 232 according to an embodiment of the present disclosure. A first zone of the sidestream distribution plate 202 has an orifice 108, and a second zone is a solid area 109 without an orifice. The liquid 134 in the trough 132 used in the chamber 232 falls through the orifice 108 and generates a jet 114 along or adjacent to the chamber wall 122a, but not along the chamber wall 122b. The jet 114 is not along the chamber wall 122b because the hollow area 109 of the sidestream distribution plate 202 prevents the flow of the liquid 134. In other words, some parts of the free water surface 116 are exposed to the jet 114, while other parts of the free water surface 116 are not exposed to the jet 114. As the jets 114 pass through the spray drop zone (gas gap) 118 and contact the free water surface 116, they penetrate the water and create a deeper air bubble entrainment zone 121 than the air bubble entrainment zone 120 created in the chamber 200 of FIG. 1a.

[0045] In one embodiment, Figure 1b shows a new distribution of jet orifices 108 on a sidestream distribution plate 202. The sidestream distribution plate 202 has the same dimensions and number of orifices as the standard distribution plate 201 of Figure 1a, but the orifices are located in sub-areas of the sidestream distribution plate. The jets 114 are generated in two parallel rows along or adjacent to the length of one side of the chamber (i.e., chamber wall 122a), concentrating Nj over only 31.5% of the available area. The total applied jet power Nj is the same as the standard design, but the applied force per unit cross section (effective area) is 3.18 times higher at 774 Watts / m 2The flow conditions established in this embodiment are quite different from standard designs. For example, the increase in Nj applied in the confined jet impact zone, combined with the positioning of the jet 114 near or adjacent to the chamber wall 122a, provides a localized increase in momentum transfer, enhancing shear forces and promoting the development of well-defined circulation cells that accelerate the vertical displacement of the bubble cloud. This allows the wall adjacent to the nozzle location to constrain the radial expansion of the diverging bubble cloud and reduce the flow rate of the bubble cloud in the short dimension D of the chamber 232. 1 This results in a greater penetration depth Hp, as the bubbles are released at a constant depth over the entire pool. This causes the bubbles to rise throughout the areas of the pool not subjected to the feedwater jets 114. Field testing of the sidestream distribution plate 202 under the above example conditions demonstrates a 34.5% increase in Hp compared to the standard distribution plate 201 design, without reversing the air bubble carryover in the chamber effluent. Additionally, the bubble recirculation cells that develop within the bubble entrainment zone 121 increase the likelihood that the feedwater present in the chamber 232 will be re-exposed to the action of the jets 114.

[0046] The flow rate and pressure drop of the system design will determine the number of orifices required for a particular distribution plate application. The orifices can vary in shape and diameter. In one embodiment, the shape is circular with a diameter in the range of 0.25 to 0.5 inches. The flow potential Q of a single orifice is 1 can be derived from the following energy equation:

number

[0047] In one embodiment, the area(s) of the distribution plate without orifices may represent 65-80% of the total distribution plate area. In other words, the area(s) of the distribution plate with orifices may represent 20-35% of the total distribution plate area. It should be noted that the area of ​​the distribution plate with orifices does not refer to the sum of the individual orifice cross-sectional areas, which represent 20-35% of the distribution plate area, but rather to the area of ​​the distribution plate involved. This includes the area between the individual orifices, the space between the first row of orifices and the chamber wall, as well as the orifice cross-sectional area. Thus, when one or more areas of the distribution plate with orifices cover an area between 20% and 35% of the total distribution plate area, only a portion of that area is constituted by the cross-sectional area of ​​the orifices.

[0048] The orifices may be spaced according to a minimum spacing between the orifice location and the chamber wall selected to avoid flow adhering to the wall that would impede jet impingement. This offset may be 0.5-1.5 inches in one embodiment, but may vary with orifice diameter and spray drop height. Additionally, the orifice spacing may be designed to avoid jet-to-jet interaction in the spray zone or head space of the chamber. The orifices may occupy substantially half the length of the chamber wall.

[0049] Of course, the above example shows only one embodiment and many variations are possible. For example, Figure 2a shows a cross-sectional top view of a distribution plate 110 installed in a rectangular oxygenator 100 having six chambers 101, 102, 103, 104, 105, 106, according to one embodiment. The width across the shorter dimension of each of the six chambers 101, 102, 103, 104, 105, 106 is D 2 where D 2 =2*D 1 The distribution plate 110 has multiple regions of orifices 108 as well as one or more solid regions 109 between the regions of orifices 108. In one embodiment, a single distribution plate can be mounted over multiple chambers that make up the oxygenator. Alternatively, in one embodiment, a corresponding distribution plate can be mounted over each chamber that makes up the oxygenator.

[0050] FIG. 2b shows a cross-sectional top view of an oxygenator 100 having six chambers 101, 102, 103, 104, 105, 106, each having a chamber wall. For example, chamber 101 has chamber walls 122a and 122b. Gas ports 112 are also shown, which allow gas to flow through the head space region of each chamber. The gas ports 112 may be off-gas ports and / or gas sources. Note that adjacent gas ports 112 are offset from one another, allowing gas to transport throughout the respective chambers. For simplicity, the chamber walls and gas ports for chambers 102, 103, 104, 105, 106 are not labeled, but it is understood that they are present.

[0051] 2c shows a side view of the oxygenator 100. In chamber 101, the jet 114 falls along both chamber walls 122a, 122b, leaving an inner portion of the free water surface 116 in chamber 101 unexposed to the jet 114, thereby generating two reverse circulation cells in the bubble entrainment zone 120. This scenario considered for chamber 101 also occurs for the other chambers 102, 103, 104, 105, 106 in the oxygenator 100.

[0052] In one embodiment, the design shown in Figures 2a, 2b, and 2c incorporates six identical chambers 101, 102, 103, 104, 105, 106 (i.e., reactor stages) with a total flow rate of approximately 2044 l / min. The total head loss across the oxygenator 100 is only 0.74 m. Liquid 134 (e.g., water) flows by gravity into the inlet trough 132 and is then distributed via distribution plate 110 along both sides of the individual chamber walls for each chamber 101, 102, 103, 104, 105, 106.

[0053] In one embodiment, referring to FIG. 2a, a top view of the oxygenator 100 with the distribution plate 110 installed provides orifice locations on the distribution plate 110 of 29 jets per chamber wall, distributed in two rows, i.e., the first and second rows are 2.4 and 3.6 cm from the chamber wall, respectively, over an area representing 15.9% of the width of each chamber (25.4 cm). The effective diameter of the orifices 108 is 9.53 mm. The water level in the inlet trough 132 is approximately 12.7 cm. The generated jets 114 drop 61 cm through the head space region 230 of each chamber 101, 102, 103, 104, 105, 106 before impacting the free water surface 116 of the quiescent zone. The treated water exits the lower open end of each chamber via the discharge slots 126, which is 10.2 cm above the floor of the receiving sump.

[0054] In one embodiment, the top view of Figure 2b, shown without the distribution plate 110 installed, also shows the direction of gas flow as it travels serially through chambers 101, 102, 103, 104, 105, 106 via gas ports 112 before exiting through a 1.9 cm diameter off-gas exhaust port. The gas travels due to a pressure differential created by the oxygen source.

[0055] In one embodiment, the end view of Figure 2c shows the location of the supply gas inlet port 112 (0.64 cm diameter) fixed to the chamber wall 122a for the chamber 101 at an elevation above the elevation of the quiescent zone free water surface 116. An interior chamber wall (e.g., chamber wall 122b) has a single 1.9 cm diameter gas port at this same elevation. These ports are staggered between a location 5 cm forward of the rear wall or 5 cm behind the front wall to establish the tortuous path (gas flow) shown.

[0056] Of course, oxygenator chambers can vary in geometry as well as scale. They incorporate nested rectangular dimensions such as those shown in Figures 1a, 1b, 2a, 2b, and 2c, for example, but most are wedge-shaped to accommodate subdivisions of subsurface oxygenators with circular cross sections. Froude-based scaling of hydraulic forces, such as the described circulation cell, is valid when gravity dominates and a free surface is involved. A scaled-up geometric similarity requires the same depth-to-width ratio in the receiving pool. In the above example, we use Hp as the depth and the short dimension of the chamber as the width D. 1 When used as a depth-to-width ratio R L becomes 1.75. o The feed water flow rate Q in the new design is fixed at 0.308 m and 6, respectively. L Increasing Hp requires a wider chamber to accommodate the surface loading rate criteria and the increased number of jets per chamber. o If the chamber width is assumed to be fixed with respect to R, increasing the chamber width ldecreases, which indicates that scale-up changes the contact conditions to be more favorable. This has been confirmed in laboratory tests. The tests show a displaced bubble plume from the jet wake rising to the surface of the pool at a certain depth, without a uniform distribution in the pool volume present outside the jet impingement zone, and the liquid volume in the chamber is now not fully utilized.

[0057] Figure 3 shows that the R L 1 illustrates a modification of the oxygenator chamber 232 that attempts to restore full utilization of the chamber volume when L reduction is limited. The vertical baffle 301 constrains the jet 114 flux and limits the interaction of the downward and upward fluid flows, reducing drag and allowing for higher bubble plume acceleration in the jet wake region 305. The horizontal baffle 303 directs this accelerated flow from the chamber wall 122a towards the opposing chamber wall 122b to provide a more complete distribution of bubbles across the chamber cross section 307. The position of the vertical baffle 301 relative to the cross section 307, the horizontal baffle 303, and the chamber walls 122a, 122b determines the L o , Vj, may be related to the jet location and the desired treatment effect. Note that the vertical baffle 301 is attached to the rear chamber wall. Furthermore, the vertical baffle 301 remains submerged and therefore does not impede the movement of pool surface water into the jet wake region 305, allowing the completion of the desired circulation cell. The extension of the horizontal baffle 303 from the wall of the cross section 307 perpendicular to the fluid flow is limited to minimize the pressure drop across the resulting slot open area 309. The baffles 301, 303 may be used together or separately, based on the deviation of the RL from 1.75 or specific design objectives.

[0058] If the increase in chamber width is significant, adding an additional set of jets can meet the performance objectives. For example, FIG. 4 shows a chamber where the cell width is doubled from 12.7 to 25.4 centimeters (compared to the LHO chamber 232) and R L4 shows an exemplary configuration where the feedwater flow rate Q is now 0.875. Also shown is a distribution plate 401 having orifices 108 along two sides with a hollow area 109 therebetween. L is twice the flow rate of the previous example (2 × 170.3 l / min), as is the total number of impinging jets (2 × 29). In this new configuration, the chamber boundary D 2 Two countercirculation cells are established with interaction at the midpoint of the two. Although not shown, the baffles 301, 303 presented in Figure 3 can be applied in pairs to improve performance.

[0059] R L The strategy used here to avoid cell distortion of =0.875 is: (1) the chamber width D 1 D 2 Increases with the increment of dimension, (2)Q L / m 2 If the chamber cross section remains constant, R L This can be applied if further reduction in D is required. 3 is 50.8cm(R L =0.438), 101.6 cm (R L =0.219), 152.4 cm (R L =0.109), etc.

[0060] Figure 5 shows the chamber width D 3 But 2D 2 The results are shown when the Q L is 4×170.3 l / min, and 4×29 impingement jets 114 are directed along the chamber walls 122a, 122b and at locations 505a, 505b adjacent the baffle 503, D 3 The latter two points are located at H above the free water surface 116 of the pool. p The net result of the new configuration is that the axially extending baffle 503 extends to a water level above R L= 0.438, the establishment of two pairs of inverted cells designed to replicate the gas-liquid contact conditions shown in Figure 3. Figure 5 also shows the two groups of jets offset from the chamber walls 122a, 122b, and the resulting orifice 108 schedule for the distribution plate 501, where both sides of the baffle 503 minimize contact of these components with the jet 114 flow above the free water surface 116. Similar offsets are used in the configurations shown in Figures 1a-1b and 3, as well as in the exemplary plate designs of circular LHO systems as shown in Figures 6a-6b.

[0061] Figures 6a and 6b provide two options for wedge-shaped chambers. Figures 6a and 6b show a cross-sectional top view of a circular oxygenator 605 consisting of eight wedge-shaped chambers, each divided by a chamber wall 602. Here, the wedges (θ w ) can be made small, typically less than 1 radian (57.3°), and therefore a uniform distribution of jet positions can be achieved by dividing the sector radius (r max ) can be based on the relative area provided by a wedge cross-section along θ 0.785 radians. For example, Figures 6a and 6b show w and 1 / 2r 2 max θ w 6 shows a circular oxygenator 605 subdivided by eight connected wedges of equal area, providing a chamber cross-sectional area of ​​.mu.m.

[0062] As shown in FIG. 2, uniformly fixing the distribution of the orifices 108 over an area representing 31.5% of the available area requires a distribution plate 601 shown in FIG. 6a with a constant flow rate (θ w ) (0.315), or 0.247 radians (14.18°). Unfortunately, if r is zero (r min Given the increasing level of jet wake constraint as one approaches θ, some distortion of the desired circulation cell will occur.

[0063] This same restriction applies to the second option, shown by distribution plate 603 in FIG. 6b, which has a r max The zone near the sector arc at θ and the origin (r min We attempt to replicate the two inverted cells shown in Figure 3 by uniformly adding jet momentum along the zone near ((1 / 2)(R 2 max )(θ w )(0.315)) / 2.

[0064] The alternative configuration shown in FIG. 7a is a rectangular section R L The use of wedge-shaped chambers is avoided by establishing a group of parallel dividers that mimic the oxygenator 706. The oxygenator 706 consists of ten chambers defined by chamber walls 701. A top view of a distribution plate 702 is also shown in FIG. 7a, which may be installed on top of the chamber walls 701.

[0065] Similarly, the configuration shown in FIG. 7b allows these same R values ​​to be stored in the annular space created by a group of concentric chamber walls 703 in a six-chamber oxygenator 708. L An example of a distribution plate 704 that can be used in the oxygenator 708 is also shown in Figure 7b.

[0066] In one embodiment, optional watertight bulkheads 710, 711, 712, 713, and 714 can be included in both of the alternative designs shown in Figures 7a and 7b to increase the number of chambers within the oxygenator system boundary and therefore improve AE and TE. In one embodiment, the watertight bulkheads 710, 711, 712, 713, 714 are airtight (except for gas ports that allow gas transfer from one chamber to the next).

[0067] In one embodiment, the orifice range in the distribution plate will be reduced due to reduced hydraulic loading (HL). For example, the HL for seawater applications is typically less than freshwater applications given that smaller bubble diameters are generated in saltwater applications, leading to deeper bubble penetration depths. To account for this, the double rows of orifices are positioned as separate groups with equal length gaps between the groups (e.g., a schedule of 8 inches of orifices followed by 8 inches of no orifices repeating).

[0068] 8a-8c show modified orifice schedules for the gas diffusion plate corresponding to various chamber configurations. The modified orifice schedule includes separate groups of orifices with equal length gaps to account for the lower HL of seawater applications.

[0069] FIG. 8a shows a quadruple wide (20 inch wide) chamber configuration with a corresponding modified orifice schedule in the gas diffusion plate 501. In FIG. 8a, the hashed portion 108 shows an area with orifices separated by equal length gaps. FIG. 8b shows the case of a single sided distribution with a 5 inch cell width.

[0070] As shown in Figure 8a, when two or more sides of the reactor distribution plate are covered with orifices, the gaps between the areas having the orifices are aligned to facilitate the creation of the opposed or opposing rotating circulation cells shown in the side views of Figures 4 and 5. Figure 8c shows how the gaps are created in the case of a circular reactor cross section.

[0071] Figures 8a-8c illustrate how water is applied when, as in this example, the water flow rate is limited to 50% of the freshwater hydraulic load limit. In other embodiments, the hydraulic load limit due to saltwater use may be greater than or less than the 50% used in this example. If so, the gap area between the orifice areas would be reduced or increased accordingly. For example, if the hydraulic load limit were increased to 75% of the freshwater target, the gap area would be equal to 25% of the linear area covered by the orifices instead of the 50% reduction shown in Figures 8a-8c.

[0072] FIG. 9 illustrates a method 900 of performing high efficiency oxygenation using a subsurface oxygenator system including two or more chambers, one or more distribution mechanisms disposed on corresponding chambers, and a gas input to each of the one or more chambers, according to one embodiment of the present disclosure.

[0073] In step 902, the subsurface multi-stage oxygenator system is submerged to a certain depth. This step is optional in that the oxygenator system may already be in place and submerged at the time of use. In this case, operation begins in step 904. In step 904, liquid is provided to one or more distribution mechanisms such that the liquid forms jets or droplets that flow into one or more chambers. Any of the distribution mechanisms described herein may be used, including sidestream distribution plates or nozzles. In embodiments using distribution plates as distribution mechanisms, each of the distribution plates has a predetermined number of orifices uniformly distributed in one or more zones of the respective distribution plate, and has no orifices in at least one remaining zone of the respective distribution plate. Liquid flows through the orifices in two or more distribution plates to generate jets. Any of the distribution plates described herein, and variations thereof, may be used. A distribution plate using the sideflow technology described herein should be adjusted to accommodate the geometry of the oxygenator system (e.g., chamber wall locations, spray drop (gas gap) height, number of chambers, and size of each chamber).

[0074] In step 906, gas is provided to each of the one or more chambers through a gas input, causing the gas to flow through a head space (gas void) portion of each of the one or more chambers and onto the liquid stored in the one or more chambers. The jets formed in step 904 contact the gas in the head space portion of each chamber and then enter the liquid in the corresponding chamber at a region disposed directly below the distribution mechanism, generating one or more circulating cells of gas bubbles within the liquid held in the corresponding chamber. In one embodiment, horizontal and / or vertical baffles fully immersed in the liquid can be attached to the walls of the chambers, which can help promote the formation of one or more circulating cells of gas bubbles.

[0075] Tests were conducted with the sidestream distribution plate 202 described with respect to FIG. 1b, as well as several additional configurations, to evaluate their relative performance under typical field conditions. Specifically, the spray drop height (L O We quantified both Hp and the oxygen transfer coefficient G in the blood. G is obtained from the integration of equation (1) and is defined as: G = ln((C * -DO in ) / (C * -DO out )) in which DO in and D.O. out are the DO concentrations of the chamber inlet and effluent, respectively. The measured G values ​​were corrected to 20°C based on equation (2) and then subtracted from the G values ​​previously established for the selected standard plate design (uniform distribution of orifices). 20C Then, specific to the oxygenator, the input was G 20CA multicomponent gas transport model requiring a 100% saturation gas flow rate was used to predict the relative performance (AE, TE, etc.) of both configurations. The test sidestream distribution plate was installed 12.7 cm deep in a rectangular chamber with dimensions 1.219 m high x 0.508 m wide x 0.127 m thick. The area created above the plate acted as a water feed trough where it received water from an adjacent quiescent zone fed by a centrifugal pump. The pump flow rate, regulated by a throttle valve and measured with a Signet type paddle wheel flow sensor, was 157 l / min. Windows installed on the sides and ends of the chamber allowed the observation of the jet, the jet impact zone (H p ) and allowed observation of the quiescent zone. The chamber was installed in a sump tank with an additional window and a drain valve used to regulate Lo via changes in the pool surface. During operation, oxygen was pumped to within the range of X of 0.65 to 0.75 while water entered the inlet trough, fell by gravity into the impact zone, and then exited the lower open end of the chamber. O2 The oxygen flow rate was fixed by a Cole-Palmer variable area flowmeter and its integral throttle valve. O2 was measured in the chamber off-gas, which was continuously discharged through a 1.9 cm riser extending through the midpoint of the distribution plate and above the free surface of the trough water. O2 DO and X were measured with both an Oxyguard Polaris TGP meter and a Quantek Model 201 oxygen analyzer. O2 Once stabilized, the change in DO throughout the system was determined by measuring the DO in the inlet trough and the DO in the sump effluent. DO measurements were made with a YSI Prosolo luminescence probe, which also provided water temperature and local barometric pressure. Lo and Hp were then measured with a tape measure. The test range for Lo was 20.3-67.3 cm. The resulting G 20 C needed to calculate the value * was based on water temperature and local pressure.

[0076] The side flow distribution plate test is 20This helped to verify the predictions of improved Hp, development of well-defined circulation cells, and enhanced gas transport potential, as shown by 、 Tests of the sideflow plate performed at Lo=30.48 cm and 60.86 cm demonstrated Hp 34.6% and 28.6% higher, respectively, than that achieved with the standard plate design. Hp varied little with Lo as shown by least squares regression of Hp vs. Lo (N=29). The insensitivity of Hp with changes in Lo may simplify the design of the oxygenator quiescent zone depth and provide increased surface loading criteria, a factor in determining device sizing. G established during steady-state runs with the sideflow distribution plate 20 The values ​​were also correlated with Lo based on regression analysis (r 2 =0.9516). This model uses the G 20 The form of the regression equation previously developed for the lateral flow G 20 is standard G 20 The percentage improvement is significant and increases with increasing Lo up to the laboratory test Lo limit (67.3 cm), e.g., at Lo = 35.6, 50.8, and 67.3 cm, the G vs. standard design is 20 The percentage improvements in are 38.1%, 57.5%, and 73.3%, respectively. 20 is the function: % removal = (1-e -G20 ) 100, dissolved gas deficiency (C * -C) is a logarithmic function related to the degree of removal. At Lo = 67.3 cm, G 20 The defect removal based on is 44.97% for the standard plate design and 64.65% for the side-flow case, an improvement of 43.76%. To further quantify the positive effect of the side-flow configuration, the LHO performance was simulated using the multicomponent gas transfer model described above. The performance was measured at standard operating conditions (15C; DO in= 8 mg / l). The oxygen feed rate was adjusted until the predicted AE matched the target AE values ​​of 70, 75, 80, 85, and 90%. Table 1 summarizes examples (8 of 20) of performance predictions when Lo was 45.72 cm. Variables tracked included required oxygen feed rate (% of water flow), DO out (mg / l), oxygen transfer rate (lbs / day), TE (lbs / hp.hr), and nitrogen transfer rate (lbs / day). [Table 1]

[0077] It should be noted that for the selected AE, the LHO incorporating the side-flow configuration is able to operate at a higher oxygen delivery rate, which increases all performance indicators. For example, the daily oxygen transfer rate was increased by 35.9% on average over the oxygen transfer rate predicted with the standard plate design. The benefits shown in Table 1 were further improved when the Lo was increased to 76.2 cm. In this case, the daily oxygen transfer was 46.8% higher than the standard plate application. Taken together, the simulation data shows that the side-flow plate design was able to operate at a higher oxygen delivery rate than the selected DO. out It has been shown that the sidestream design can be used to reduce the hydraulic head required for or improve the performance of a subsurface oxygenator where Lo is fixed. The sidestream design also provides enhanced nitrogen removal capacity.

[0078] Bio-fouling is expected in marine net pen applications. Coarse spray nozzles have limited sensitivity to bio-fouling given the relatively large water orifice geometry and high water velocity. Gas transfer occurs primarily across the droplet surface after release from the nozzle, with some beneficial effects expected at the nozzle during droplet formation and upon impact with the receiving water. In one embodiment, the diameter of the drop produced by the nozzle is in the range of 500-1000 micrometers. The drop diameter is related to

number

number

number

[0079] For stripping, the concentration of the jets along the chamber walls and / or vertical baffles makes the head space region (gas void) of each chamber available for application of scrubbing component inserts. In one embodiment, scrubbing component inserts can be installed in the head space region of one or more chambers to perform stripping. Figures 10a-10c illustrate three exemplary configurations of chambers 901, 903, and 905 using scrubbing inserts 910, 911, and 912, all based on selectively reacting DC desorbed from jet 114 using a short packed bed (914 or 915) irrigated with 2N NaOH solution, although it can be understood that other solutions besides NaOH can be used in other embodiments. The NaOH solution can be applied by one or more solution supply lines 907 (e.g., nozzles, liquid distributors) and then collected in a sump 909 plumbed to one or more source pumps for recirculation and reuse. Additionally, the scrubbing solution recirculation loop may be specific to a single stage of a multi-stage oxygenator, or may be specific to a group of chambers with a single oxygenator, or may be specific to a selected group of oxygenators within an aquaculture facility. The pH of the scrubbing solution may be maintained at or above a predetermined value (e.g., 11.4) with the addition of NaOH in a feedback loop. NaOH reacts with DC to produce sodium carbonate (NaCO), which has a lower equilibrium pH. 2 CO 3 ) can be formed. Spent NaOH and Na 2 CO 3 The mixture is then mixed with hydrated lime (Ca(OH) 2 ) can be regenerated for reuse in batch processes. Ca(OH) 2 +NaOH produces the product CaCO 3 +NaOH is generated. CaCO 3 The NaOH can be separated from the mixture by gravity and / or filtration before being reused.

[0080] Alternatively, a packed bed (914 or 915) disposed within the scrubbing insert 910, 911, or 912 may be used to react Ca(OH) 2 +CO 2 Promotes CaCO 3 The scrubbing insert 910, 911, or 912 may be directly irrigated with a hydrated lime solution that produces a pH of 1.0-1.5. The elevated pH scrubbing solution feed rate to the scrubbing insert 910, 911, or 912 may represent a small percentage of the water flow through the oxygen absorber, given the positive effect of chemical reactions on the gas transfer rate, quantified by the enhancement factor β (Equation (1)), the ratio of gas transfer with and without chemical reactions. Absorption of DC is considered a pseudo-first order reaction with respect to DC, when the concentration of OH in the bulk scrubbing solution is relatively high and varies little across the scrubbing insert 910, 911, or 912. β values ​​of 8 to 250 have been reported for scrubbing DC with NaOH in a packed column, and β values ​​of 1.2 to 60 for ball and bubble columns. In one example, the gas transfer rate increases rapidly with increasing NaOH normality up to about 2N. Given the concomitant increase in solution viscosity, further increases in normality may decrease the gas transfer rate. The NaOH in 2 CO 3 As the conversion to NaOH increases, the gas transfer rate may also decrease, so a feedback control loop is incorporated that can adjust the addition of NaOH based on the scrubber solution pH. Scrubber performance can also be improved by increasing the packing irrigation rate, the gas feed rate, and increasing the scrubber solution temperature. It will be appreciated that the scrubbing solution used attempts to reach equilibrium with the head space gas according to equations (1)-(5) including oxygen. Thus, the scrubbing solution may become supersaturated with oxygen in some cases, such as in chambers close to the gaseous oxygen feed point (e.g., chamber 101 of oxygenator 100). Thus, the scrubbing solution sump and other recirculation loop components outside the oxygenator shell can be designed to minimize or eliminate exposure of the solution to the local atmosphere to stop oxygen loss from the system by desorption.

[0081] 10a-10c show that each chamber 901, 903, and 905 has a dedicated NaOH solution supply line 907 and sump 909 drain line, which in this example passes through the airtight oxygenator shell. The installation of scrubbing inserts 910, 911, or 912 ensures that (1) there is no interference with gas transfer between the chambers, (2) there is no direct contact with the jet 114, and (3) there is no leakage of NaOH into the quiescent zone 124. CO 2 Scrubbing efficiency is controlled by the pH of the NaOH solution, packing type and depth, NaOH irrigation rate, and head space gas throughput.

[0082] 10a shows an end view of chamber 901 similar to chambers 101, 102, 103, 104, 105, 106 from multi-stage oxygenator 100, but with the addition of a scrubbing insert 910 attached to one or more chamber walls and within head space region 230 adjacent to, but not in direct contact with, jet 114. In other words, scrubbing insert 910 is located below solid region 109 of distribution plate 110 that does not have an orifice. Scrubbing insert 910 includes solution feed line 907, exhaust vent 913, packed bed 914, chimney 917, chimney cap 919, sump 909, and skirt 921. Solution feed line 907 discharges NaOH into packed bed 914, which spreads the NaOH solution over the various distribution points as it flows downward toward sump 909. In one embodiment, the amount of NaOH solution released by the solution supply line 907 may vary based on the pH of the scrubber solution, which may be known in advance and / or measured in real time using a pH sensor and corresponding circuitry. When the jet 114 contacts the free water surface 116 and generates a circulating cell of bubbles in the quiescent zone 124, the scrubbing insert 910 captures the rising gas bubbles using a skirt 921 that is partially immersed in the quiescent zone 124. The skirt 921 may act to separate the rising gas bubbles from the jet 114. This gas may then rise above the free surface of the NaOH solution in the sump 909 through a chimney 917 to the packed bed 914. A chimney cap 919 prevents leakage of NaOH into the quiescent zone 124. The downward flowing NaOH solution and the upward rising gas react as they come into contact. The treated gas exits the top of the scrubbing insert 910 through exhaust ports 913, allowing gas recirculation in the area near the jets 114 and just below the lower surface of the sidestream distribution plate 110. The ceiling of the scrubbing insert 910 eventually acts to push the treated gas towards one of the exhaust ports 913.

[0083] FIG. 10b shows an end view of chamber 903 similar to chamber 901 discussed with respect to FIG. 10a, but without skirt 921. Additionally, chamber 903 shown in FIG. 10b allows head space gas to passively diffuse in and out of packed bed 915 via strategically positioned openings 923 on the sides and ends of scrubbing insert 911. Note that openings 923 may be configured to prevent intrusion of jet 114 into high pH packed bed 915 and sump 909, as well as to prevent NaOH leakage. In one embodiment, this may look like using a roof 925 angled away from jet 114 and toward packed bed 915. In this example, packed bed 915 is slightly smaller than packed bed 914 in FIG. 10a to accommodate roof 925. Additionally, for simplicity, chamber 903 has four pairs of openings 923 and roof 925, although only one pair has been labeled. It may be understood that the number, location, and / or configuration of the openings 923 and / or roof 925 may vary in other scenarios.

[0084] FIG. 10c shows an end view of a chamber 905 similar to the chamber 901 discussed with respect to FIG. 10a, but with the addition of a fan 927 that is low powered, rated for oxygen supply, and may be configured to provide gas flow through the packed bed 914. In this example, the fan 927 draws gas generated by the bubble circulation cells from near the free water surface 116 through the chimney 917 toward the packed bed 914 (as indicated by the dashed arrow). The fan 927 is attached to the chimney cap 919 in this exemplary embodiment, but the fan 927 (either the same fan or an additional fan) may be positioned in other locations in other embodiments. For example, a second fan may be positioned above the ceiling of the scrubbing insert 912 to pull gas up from a lower region of the packed bed 914. As another example, the rotation of the fan 927 may be reversed to draw gas from the head space region of the jet 114 and direct the gas downward through the packed bed 914 for discharge through the chimney 917.

[0085] If the volume of head space available to the scrubbing insert 910, 911, or 912 is limited, the scrubbing insert 910, 911, or 912 can be elevated above the distribution plate 110, at least in part, by penetrating the distribution plate 110 with an airtight enclosure designed not to interfere with the active orifices 108 of the distribution plate 101.

[0086] The incorporation of scrubbing inserts may be implemented in any of the chambers described herein, as well as variations thereof. For example, one or more scrubbing inserts may be installed in head space regions of circular chambers, rectangular chambers, chambers with horizontal baffles, chambers with vertical baffles, etc. As can be appreciated, the shape of the scrubbing inserts may also vary to accommodate various chamber geometries. Additionally, in oxygenators having multiple chambers, one or more scrubbing inserts may be installed in a selected number of chambers or in each chamber. Additionally, the described irrigated packed beds may be used to reduce head space CO2 emissions. 2 It is understood that the scrubbing agent can be replaced with a granular / porous (dry) reagent capable of capturing the oxygen. Such reagents include lithium hydroxide, metal organic frameworks (MOFs), zeolites, mesoporous silica, clays, porous carbon, porous organic polymers (POPs) and metal oxides. The use of dry reagents can avoid oxygen carryover in the scrubbing solution as described, and the scrubbing insert can be designed with an access port specific to the oxygenation stage that allows removal of spent reagent and replacement with fresh reagent. Certain spent dry reagents can be regenerated for reuse in a separate processing step that can include heating and forced air exchange.

[0087] 11 illustrates a flow chart outlining a method 1000 according to one exemplary embodiment. Steps 1002-1006 are the same as steps 902-906, respectively, from method 900. Method 1000 adds the additional capability of being able to perform stripping by utilizing the head space made available by the incorporation of a sidestream distribution plate as described herein. Scrubbing inserts (e.g., scrubbing inserts 910, 911, 912) are installed in the head space region and can perform stripping of gas released from the bubble circulation cell using a scrubbing reagent.

[0088] Step 1008 is to provide a scrubbing reagent to the packed bed (e.g., packed bed 914 or 915). In one embodiment, a solution feed line provides the scrubbing reagent (e.g., NaOH, Ca(OH) 2 ) into the packed bed. The scrubbing reagent can be distributed near the upper portion of the packed bed so that it flows downward by gravity. The scrubbing insert can include a sump located below the packed bed to capture the scrubbing reagent and prevent it from leaking into the quiescent zone. The scrubbing insert can also include a chimney cap to prevent the scrubbing reagent from leaking into the quiescent zone in areas not covered by the sump. In one embodiment, the packed bed can be directly irrigated with the scrubbing reagent (e.g., hydrated lime).

[0089] Step 1010 is to direct the gas from the bubble circulation cells through the packed bed. In one embodiment, this is done by installing a scrubbing insert directly above where the gas from the bubble circulation cells originates. As the gas floats upward, it can flow into the scrubbing insert and pass through the packed bed. A skirt can also be used to direct the gas towards the packed bed and away from any jets. In one embodiment, one or more fans can also be implemented to push and / or pull the gas through the packed bed and exhaust. In one embodiment, step 1010 can be performed before step 1008 or simultaneously with step 1008.

[0090] As the gas from step 1010 is directed through the packed bed, the gas reacts with the scrubbing reagent provided in step 1008 to remove CO from the gas. 2 As the gas reacts and eventually exits the packed bed, it can flow through an exhaust port and be recycled to the nearby jets. The gas can be directed to flow through the exhaust port through the ceiling of the scrubbing insert, which acts to contain the gas and ultimately direct it towards the exhaust port and / or fan. Alternatively, as previously mentioned, the fan can act to draw the gas near the jets through the exhaust port and through the packed bed.

[0091] While the above description has focused on non-pressurized oxygenator designs, the systems and methods described herein can be implemented as vacuum degassers or medium pressure (sidestream) oxygenators. Sidestream distribution plates can improve AE and TE by reducing the vacuum requirements of the column, thereby reducing operational costs and providing savings in oxygen supply requirements.

[0092] In one embodiment, a vacuum degasser operating with a sidestream distribution plate can flood the water over a vessel holding the water and the distribution plate where the distribution plate is isolated from the atmosphere (e.g., by a blind flange covering the open top of the trough). The feed water jet generated by the distribution plate can fall into the quiescent zone of the chamber and then exit the chamber to a water pump via a flanged pipe connected to the bottom of the chamber. The free surface of the quiescent zone can be adjusted to a target L by installing a water jet exhaust at a suitable height above the bottom flange plate of the chamber. o The exhaust can be maintained at a level providing an oxygen inlet and the bottom flange plate has no discharge slots. The exhaust can draw off-gas from the last chamber of the multi-stage reactor, thus causing sequential head space gas movement from the oxygen introduction point (i.e., the first chamber) to the last chamber through the individual chamber gas ports. These ports can be located above the free surface of the quiescent zone.

[0093] The performance of the water jet exhauster is degraded by flooding, and adjustments to the gas or water feed rate ensure that the free surface of the quiescent zone is not changed. The exhauster is supplied by a dedicated flow of high pressure water, which transfers the energy required to extract and evacuate the off-gas from the last chamber. A high vacuum level in the chamber can be generated by a water pump coupled to the lower column discharge flange. Because the internal free surface of the chamber is fixed by the water jet exhauster, the pump can draw water from the inlet throttle valve without entraining air. The water pump can also provide the necessary discharge pressure to deliver the treated water to its point of use. The vacuum and water flow rate can be adjusted by changes to both the inlet and pump discharge throttle valves. With this configuration of reactor chambers, as well as the desired L o The positioning of the water jet exhaust at just the right elevation point to provide this eliminates the need for a downstream off-gas separator prior to pump operation.

[0094] The systems and methods described herein may also be embodied in a pressurized multi-stage oxygenator (MHO) that uses a sidestream distribution plate. Water may be forced through pumping into the flooded distribution plate zone of the sealed column (i.e., above the sidestream distribution plate) and then fall as a jet onto the free surface of the quiescent zone. The water provides the necessary quiescent conditions to separate the bubbly water before releasing the water through a valved discharge port. Partially restricting this valve may increase the column gauge pressure, provided by the feedwater pump, to a target level. Oxygen may be metered into the first chamber of a multi-chamber system. Off-gas may exit the system through a float valve coupled to the final chamber. Valve position may regulate the release of off-gas based on the reduction in quiescent zone depth caused by the oxygen supply rate exceeding the oxygen absorption rate. As with the vacuum degasser, gas release sequentially initiates gas transfer from the first chamber to the last chamber through individual gas ports positioned in the chamber wall above the free surface of the quiescent zone. The chamber walls can extend well below the bubble entrapment zone to prevent bubbles from escaping the boundaries of the individual chambers. The chamber walls are also airtight where they intersect with the underside of the water distribution plate as well as the system shell.

[0095] Field testing and subsequent computer simulations have shown that the new sidestream distributor plate configuration improves the AE and TE of subsurface oxygenators as well as alternative reactors using perforated distributor plates. Alternative reactors include multi-stage sidestream oxygenators operating at positive gauge pressure. Subsurface applications in net pens and semi-contained net pens are very attractive given the relative ease of utilizing hydrostatic pressure available in deep-sea rearing locations both within and outside the pen boundaries. Passive pressurization of the reactor accelerates oxygen transfer providing effluent DO well above local air saturation concentrations, minimizing the size of the equipment as well as the required energy input.

[0096] In one embodiment, the dissolved gas deficit that drives the gas uptake rate is the mole fraction of oxygen, X O2 above the mole fraction of the local atmosphere (0.20946), and the pressure P at which gas transfer occurs T It is possible to operate within the confines of a gas-tight reactor by increasing the saturation concentration of the gas in the solution (C * ) is determined by its partial pressure in the gas phase (Equation (4) and Equation (5)). For example, by immersing the reactor at 12°C, P T Increase the pressure from 1 atm to 3 atm, and X O2 At =0.6, C * from 30.85 mg / l to 93.42 mg / l. When the ambient DO is 5 mg / l, the corresponding dissolved gas deficit and the resulting gas transfer rate increase by a factor of 3.42 (Eq. (1)). The total absolute pressure in the reactor is calculated by the local atmospheric pressure, BP (mmHg), salinity and immersion depth (Z, m), i.e., P T For example, at a salinity of 35 ppt, pg = 75.8 mmHg / m, depth Z is set to 37 m, and the local BP is 760 mmHg, P T is calculated to be 3564.6 mmHg. The resulting gauge pressure of 280.46 cmHg (54.2 psig) is remarkable, given that the reactor effluent DO far exceeds local air saturation concentrations, providing sidestream treatment with blending. This was accomplished without the pumping required to operate surface-based pressurized packed columns and venturi-based oxygenators.

[0097] In the above example, O 2 The mole fraction of X was set to 0.6. By design, this term decreases with increasing X as the off-gas moves from the first stage to the last stage of the multi-stage reactor. O2 The degree of change depends on the oxygen supply rate, K La, temperature, DO, nitrogen stripping, hydraulic loading, and pressure. These changes are tracked stage by stage by proprietary software incorporating a group of finite difference mass transfer calculations. Overall reactor performance is also summarized by the software including effluent DO, TGP, oxygen transfer rate (lb / day), AE, TE, and transfer costs. The software was used to investigate the performance characteristics of a subsurface oxygenator (8 stages) operating at each of four depths: 0 ft, 24 ft (7.3 m), 65 ft (19.8 m), and 107 ft (32.6 m). The effective water jet or spray fall zone (L 0 ) was fixed at 30 in. (0.762 m) in all cases. Simulations were performed with previously established gas transfer coefficients for both the selected standard and high efficiency (sidestream) water distribution plates. The conditions selected included a temperature of 12°C, an inlet DO of 5 mg / l, a BP of 760 mmHg, a salinity of 35 ppt, a feed gas purity of 93%, and a cost of electricity of $0.15 / kW-hr. The inlet DN was assumed to be the surface saturation level calculated based on the solubility coefficients. The water flow rate through the reactor was fixed at 2000 gpm based on an analysis of a net pen design that used multiple pumps to deliver a total feedwater flow rate of approximately 95,000 gpm from a depth of approximately 40 m. In this example, the subsurface reactor flow represents only 12.6% of the total flow entering the pen. The maximum average daily oxygen demand was calculated considering the maximum expected feed rate by the standard formula. Peak rates typically occur in the late afternoon and can represent 1.4 times the daily average rate. In this example, the daily average and peak rates are 2,769 kgO 2 / day and 3,877 kgO 2 / day. Environmental data indicates that ambient feedwater DO at net pen production sites can be as low as 5 mg / l. This concentration is generally considered the lower limit of acceptability for salmonids, so in these worst-case conditions, the oxygen demand of the cohort cannot be reduced by natural oxygen sources and must be provided by the oxygenation system. The calculated DO addition rates to the pen feedwater after blending with the oxygenator effluent are 5.3 and 7.5 mg / l for maximum daily average and peak demand, respectively. The corresponding oxygenator effluent DO requirements before dilution are 47.3 and 64.3 mg / l. These concentrations are beyond the economic capabilities of non-pressurized oxygenators.

[0098] Table 2 summarizes the predicted performance of an exemplary oxygenator corresponding to the above example for depth of operation at two selected AE values ​​(75% and 92%). Again, the simulation was based on two distribution plate configurations, the selected standard design and the sidestream high efficiency design of the present embodiment. Note that the effluent DO, oxygen transfer / day, and TE rise dramatically as the depth increases from 0 to 107 feet. For example, the effluent DO (for sidestream) rises 4.17 times from 17.9 to 92.9 mg / l when AE is set to 75%. The effluent DO for both plate configurations meets the predicted peak make-up requirements, but enhanced performance is provided by the sidestream distribution plate design. The predicted TE values ​​are very high, with 30.44 lbs O for this series. 2 / hp-hr or 22.7 kg / kW-hr. This value significantly exceeds the range previously established for land-based LHO (5.5 kg / kW-hr), as well as pressurized packed columns (1.0 kg / kW-hr) and Venturi-based injectors (0.5 kg / kW-hr). To further explore the benefits of subsurface operation, a 987.5 lb. O 2The effect of depth of operation on the required water flow rate through the reactor, power requirements, and reactor cross-sectional requirements (scale) required to provide a new target for oxygen transfer at 107 ft / day were established. All of these, including relative values, are summarized in Table 3. Note that the reactor flow requirements drop dramatically as depth increases. In this example, the flow rate, distribution plate area, and power requirements at 107 ft represent only 9.1%, 9.1%, and 3.6%, respectively, of the values ​​required at sea level. Additionally, the pump operating power required to establish the gauge pressure associated with 107 ft immersion was reduced from 70.31 hp to 2.53 hp.

[0099] Table 2 below summarizes the oxygenator performance versus immersion depth when operating at 75% and 92% oxygen absorption efficiency. Calculations were based on the use of both standard and sidestream liquid distribution plates selected. Water flow rate is 2000 gpm in all cases. G / L is the feed gas to liquid ratio expressed as a percentage. [Table 2]

[0100] Table 3 below shows the O of 987.2 lbs for the operating depth. 2 This is a summary of relative water flow rate, pumping power, and reactor cross-sectional area (scale) requirements to achieve an oxygen delivery rate of 100 / day. Performance data was collected from Table 2. (Standard plate data only when operating at T=12C°, DOin=5mg / l, combined pump and motor efficiency=0.6, 8 stages, 30 inch spray drop, salinity=35ppt, gas oxygen purity=93%, oxygen absorption efficiency (AE) 92%.) Relative flow rate (percent), relative power (percent), and relative area (percent) are calculated as the ratio of the variables at a depth of 0 feet. [Table 3]

[0101] Embodiments of the present disclosure include subsurface designs suspended at a set depth via anchoring, mooring, ballast and reserve buoyancy or a combination of the like. Such embodiments may be located within a semi-contained net pen, outside of a semi-contained net pen enclosure with installation adjacent to existing suction lines leading to one or more feedwater pumps, and outside of a semi-contained pen but directly coupled to individual feedwater suction lines without the possibility of sidestream treatment. That is, some embodiments rely on submerged ultra-low head axial pumps for delivery of design flow rates. Other embodiments utilize existing feedwater pump suction to pull water through the oxygenator, thus eliminating the need for additional pumping hardware.

[0102] FIG. 12 shows a side view of a reactor 1100 designed to be installed at a fixed depth in a net pen and semi-contained net pen enclosure. As shown, the system consists of three main components: a hooded reactor 1101 that receives water and commercial oxygen, an axial pump 1102 coupled to a water delivery riser 1103, and a ballast system 1104 to keep the reactor submerged and stabilized when lowered into position. A cable connection 1105 connects to cabling (not shown) for raising and lowering the reactor assembly. The cabling may also support motor wiring, oxygen supply hoses, a snorkel tube with valve 1106, and instrumentation signal lines. Motor torque requirements must also be considered. During operation, the snorkel tube valve is opened to allow the reactor to purge trapped air as the reactor assembly is lowered to a submerged position. At the target depth of operation, the snorkel tube valve is closed and the pump is turned on. Water (2000 gpm) is forced into a flooded head space 1107 and then flows with a pressure drop across the distribution plate 1108 through a flooded spray zone 1109, a quiescent zone 1110, and a collection zone 1111 before exiting the reactor via circumferential discharge slots 1112. The circumferential discharge slots 1112 act to mix the product water with the net pen bulk flow.

[0103] At this point in the start-up procedure, oxygen is directed to stage 1 of the eight-stage reactor, as detailed in Figures 13a and 13b. The oxygen travels down through the spray zone 1202b of stages 1-8 via gas port 1201b to an elevation equal to that of the open end of the off-gas port 1203a coupled to the end wall of chamber 8. A water jet is generated within the generated head space and off-gas is continuously discharged from the exhaust port 1203a. Note that the quiescent zone 1204b allows for entrained bubble formation and retention to facilitate gas transfer, but also prevents bubble washing. An access hatch at the top end of the reactor allows for inspection / cleaning of the distribution plate or nozzles when not in use. The oxygen supply rate is regulated and measured at the surface based on DO demand. This process may be automated and may include a motor speed control and an ambient water DO sensor coupled to a motorized gas regulation valve. As shown in FIG. 12, treated water exits through continuous circumferential slots or intermittent slots 1112 at the base of the reactor. The discharge is pumped out of the pump inlet towards the sea surface to prevent water recycling through the slots shown or a plumbed manifold / distributor. The ballast requirements for reactor stability at the lower end of the unit and the ballast location below the reactor bottom plate must be designed taking into account expected current forces, materials of construction, and gas voids that will be established in the water jet zone. Similarly, pump inlet screening, or filtering requirements, are related to solids loading. In one embodiment, this is an open reactor design with a pressure drop of about 4' across the reactor. Thus, the reactor shell is not acting as a high pressure vessel that needs to be able to handle the hydrostatic pressures generated by subsurface operation. The embodiment shown in FIG. 12 is flexible in scale and can be manufactured to handle a wide range of water flow rates and oxygen make-up rates. The overall height of the reactor portion of the assembly can remain consistent with FIG. 12, but the reactor diameter, riser pipe diameter, orifice schedule, and ballast can be altered to match the hydraulic load.

[0104] FIG. 14 shows a side view of the assembly of FIG. 12 modified to allow positioning at a constant depth outside the confines of the semi-contained net pen. Again, oxygen is directed through an eight-stage reactor with water jet zone. In this case, the depth of the unbaffled water collection zone 1301 has been increased to accommodate delivery of product water via pipe stub 1302 to the covered inlet 1303 of the net pen feed water pump 1304. This configuration eliminates the circumferential discharge slot of FIG. 12 and instead relies on dilution and delivery of oxygenated water via net pen feed water pump action. As explained above, the number of units applied can be varied and the output can be scaled up or down to meet target delivery rates. Direct coupling of the reactor to an existing suction line provides a simple means of neutralizing the torque generated by the axial pump. Alternatively, a centrifugal pump can be used to minimize torque effects by mounting the pump with the discharge directed on a riser leading to a distribution plate with the pump motor and impeller operating at a 90 degree offset from the vertical axis of the reactor.

[0105] FIG. 15 shows a side view of the assembly of FIG. 12 modified to utilize the suction lift potential of the semi-contained net pen feed pump to eliminate the need for a separate low head pumping step. Here, the net pen pump 1401 draws water into the reactor inlet port 1402, which resides on the surface of the upper domed hood 1403, after passing through an inlet screening or filter 1410. The water is then directed through a perforated distribution plate 1404, a water jet zone 1405, a quiescent zone 1406, and a water collection zone 1407, before entering the open end of the pump suction line 1408. The reactor stages and oxygen flow paths are the same as those shown in FIG. 13. The off-gas outlet port 1409 to maintain the free surface of the water jet zone relies on a float-actuated gas release valve coupled to a gas snorkel that in this embodiment extends just beyond the free surface of the ocean. This new configuration is required given that the gauge pressure of the water spray zone is lower than the hydrostatic pressure present at a certain depth, but higher than the hydrostatic pressure present at the sea surface. Cabling and ballast requirements for reactor stabilization are related to pump suction line geometry / materials of construction as well as local hydrodynamic conditions, e.g., water flow. Head requirements for operation will add to the demands on existing feedwater pumps, which may require upgrades in power or impeller design. Reactor scale can be adjusted to match the hydraulic load of the feedwater pumps.

[0106] FIG. 16 shows a side view of the reactor of FIG. 12 modified to operate as a sidewall reactor, utilizing hydrostatic pressure provided by a large diameter, deep RAS circular rearing tank. In this embodiment, the outer shell of the reactor is a pressure vessel operated through the application of an angle-driven low head axial pump 1501. The angle drive allows the use of an air-cooled motor that rejects heat added to the treated water. The reactor interior is the same as that of FIGS. 12 and 13, but in this case the water collection zone 1502 has been increased to accommodate the use of a screened water return line. The intake and return line orifices can be oriented to promote mixing of the tank. Similar to the configuration of FIG. 15, the off-gas exhaust coupled to stage 8 is a float-operated gas release valve 1503.

[0107] FIG. 17 shows the main components of a spray nozzle reactor 1600 designed to mount directly to a net pen suction line, as in the embodiment shown in FIG. 14. In this embodiment, the spray nozzle system serves as the liquid distribution mechanism instead of a perforated distribution plate. The main components of the system are a hooded reactor that receives water and commercial oxygen, an axial pump 1601 coupled to a water delivery riser 1602, and a ballast system 1603 to keep the reactor submerged and stabilized when lowered into place. As in the distribution plate design, a surface cable connection 1604 connects to the cabling used to raise and lower the reactor assembly, as well as to support the motor wiring, oxygen supply hose, snorkel tube, and instrumentation signal lines. As in the previous embodiment, motor torque requirements must also be considered. During operation, the snorkel tube valve is opened to allow the reactor to purge trapped air as the reactor assembly is submerged in place. At the target depth of operation, the snorkel tube valve is closed and the pump is turned on. Water is forced into a manifold 1605 that leads to nozzles 1606, from which it flows through a flooded (gas void) spray zone 1607, a quiescent zone 1608, and a collection zone 1609 before exiting the reactor via a pipe stub 1610. The pipe stub 1610 acts to mix the product water with the flow in the net pen pump suction line.

[0108] Spray nozzles are available in a variety of sizes and materials, including stainless steel. The total nozzle capacity is easily adjusted by varying the pressure drop, nozzle diameter, and number of nozzles used in a particular design. Excessive wave action or flow can cause problems in subsurface applications, given the potential for inducing wall flow via tilting or gas pumping in individual reaction chambers. Thus, the distribution mechanism should be selected based on the expected wave and flow forces.

[0109] During the start-up procedure, oxygen is directed to stage 1 of the reactor. For example, an embodiment with a five-stage reactor 1700 using nozzles similar to reactor 1600 of FIG. 17 is shown in FIG. 18. Oxygen travels through stages 1-5 via gas port 1701 to an elevation equal to the open end of off-gas port 1702 coupled to the end wall of chamber 5. A water droplet spray then develops in the head space (gas void) and off-gas is continuously released through the exhaust port. Note that, like the distribution plate design, the quiescent zone allows for entrained bubble formation and retention to facilitate gas transfer, but also prevents bubble washing. An access hatch 1703 at the top end of the reactor inlet manifold allows for inspection / cleaning of the piping / nozzles when not in use. The nozzles can also be flanged for quick removal and inspection. The oxygen supply rate is adjusted and measured at the surface based on DO demand. This process can be automated with equipment that may include a motor speed control and an ambient water DO sensor coupled to a motorized gas regulation valve. Ballast requirements at the bottom end of the unit located below the reactor bottom plate must be designed to account for expected current forces, materials of construction, and gas voids established in the head space or jet zone. Similarly, pump inlet screening or filter requirements are related to solids loading. In terms of materials of construction, the embodiments of Figures 17 and 18 relate to open reactor designs, so the reactor shell is not functioning as a high pressure vessel that must be able to handle hydrostatic pressures generated by subsurface operations or pumping. The embodiment of Figure 18 is flexible in scale and can be produced to handle a wide range of water flow rates and oxygen make-up rates. The overall height of the reactor portion of the assembly can remain consistent with Figure 18, but the reactor diameter, riser pipe diameter, nozzle size, and ballast can be altered to match the hydraulic load. In the exemplary embodiment illustrated in Figure 19, the water delivery pipe rises through the center of the reactor and is plumbed to a submersible pump located below the reactor at a certain depth.This acts to transfer the load of the attached pumps and ballast to the reactor shell through the internal chamber baffles, lowering the center of gravity of the reactor and providing a restoring couple that tends to rotate the reactor back to its original position after being rotated by, for example, local water currents; i.e., a condition for stability of a body (reactor) fully immersed in a fluid (water) is that the center of gravity of the body must be below the center of buoyancy. The center of buoyancy of the reactor is the center of mass of the displaced volume of the fluid (the gas void of the reactor) and it is through this point that the buoyancy force acts vertically downwards. The weight of the reactor acts vertically downwards through the center of gravity.

[0110] Figure 19 shows a spray nozzle reactor designed to be positioned at a fixed depth within the confines of a net pen or semi-contained net pen. In this embodiment, like reactor 1800 shown in Figure 12, the treated water exits through a continuous circumferential or intermittent slot 1801 at the base of the reactor. The discharge is directed toward the sea surface from a pump inlet to prevent recycling of the water. Alternatively, the combined discharge from the reactors can be combined and directed through a perforated manifold extending from the reactor in one or more directions to distribute and mix the treated water with the net pen water.

[0111] Although the reactors 1600 and 1800 illustrated in Figures 17 and 19 draw water from below via an axial pump (1601 in Figure 17), other methods of drawing water are possible without departing from the scope of this disclosure. For example, a pump can be disposed above the reactor and / or at the surface of the water to push water down into the reactor from above. In this reactor design, the water enters the top of the reactor through its dome or a series of nozzles, such as the nozzle illustrated in Figure 17. This avoids any limitations on the depth at which the pump can operate due to pump shaft seals. This reactor design also advantageously allows the pump to be "non-submersible", further reducing costs and facilitating maintenance and repair. The pump can be connected to the reactor via hoses or pipes, as one skilled in the art will recognize.

[0112] Additionally, the nozzles can be positioned to spray water from the bottom of the head space portion of the reactor to increase droplet residence time for enhanced gas transfer and minimize small air bubble formation at the interface between the interior head space and the free surface of the water. This limits the possibility of air bubbles being swept out of the reaction chamber, for example in salt water applications. As one skilled in the art will recognize, many other variations are also possible.

[0113] Table 4 shows the DO, oxygen transfer rate (OTR), and transfer efficiency (lbs O) for the standard, side stream, and spray nozzle effluent. 2 The relative performance of the spray nozzle systems is compared based on the mass transfer coefficient (G / Hp-hr) of the test 3-inch nozzle, the corresponding gas-to-liquid ratio at the inlet, and the percent of required OTR provided by each system / condition. 20 ) was determined. This information was then used to calibrate existing subsurface oxygenator software that allows prediction of reactor performance at depths of 24, 65, and 107 feet. Operating conditions were the same as those used to generate the data in Tables 2 and 3 described above. Table 4 compares the performance with a reduced-scale (1000 gpm) distributor plate reactor (6 stages) using selected standard and sidestream-based mass transfer coefficients when operated at 90% oxygen uptake efficiency. The values ​​in Table 4 show that the standard mass transfer correlation at 107 feet, the sidestream mass transfer correlation at 65 feet and 107 feet, and the spray nozzle mass transfer correlation at 65 feet and 107 feet all met or exceeded the required OTR. It should be noted that while the spray nozzle system provides the highest effluent DO (96.5 mg / l), OTR (1097.9 lb / day), and reserve capacity (222.4%), the increased power requirements dictate reduced transfer efficiencies that are well below those provided by the perforated sidestream distribution plate design. The spray nozzle transfer efficiency values ​​at 65 and 107 ft are very good (4.33 to 6.67 lb O 2The required pumping power for the spray nozzle and perforated plate system is approximately 7 and 1.5 hp, respectively, assuming a combined pump and motor efficiency of 70%. These values ​​are low and suitable for offshore missions. Given the large orifice size and ease of nozzle access provided by the external manifold shown in Figure 18, the maintenance requirements for the spray nozzle based oxygenator are expected to be lower than the perforated plate design. Furthermore, the spray nozzle system should be less sensitive to wall flow problems associated with current induced reactor tilt.

[0114] Table 4 below shows a summary of the performance of the subsurface multi-stage oxygenator versus immersion depth when operating at 90% oxygen absorption efficiency. The calculations were based on the use of selected standard distribution plates, sidestream distribution plates, and spray nozzle liquid distributors. T=12C, DO 入口 = 5 mg / l, head loss for both standard and side stream designs = 4', head loss for spray nozzle system = 19', water flow rate = 1000 gpm. Required O 2 The transfer rate is 493.8 lbs / day. [Table 4]

[0115] The location of the multi-stage oxygenation system relative to the fish pen will now be described with respect to Figures 20 and 21. For example, Figure 20 shows an oxygenation system according to an exemplary embodiment of the present disclosure, for example, submerged and connected to a water inlet pipe. As can be appreciated, the oxygenation system may have sufficient ballast to remain at a desired depth and may be fixed or tethered to maintain its position relative to the fish pen. The inclusion of ballast in the oxygenation system is also illustrated in Figure 20.

[0116] FIG. 21 also illustrates a submerged multi-stage oxygenation system according to an exemplary embodiment of the present disclosure. In FIG. 21, the oxygenation system is connected to the inlet water supply line of the fish pen, and is also connected to an oxygen supply, and an electrical supply to power the pump or pumps of the oxygenation system. Although FIG. 21 illustrates that the oxygen and electrical supplies are located on the fish pen, other locations for these supplies are also possible without departing from the scope of the present disclosure. Similarly, in both FIG. 20 and FIG. 21, the oxygenation system is shown at a certain depth near the bottom of the fish pen. However, the oxygenation system may be submerged at any depth without limitation. Thus, the relative location of the oxygenation system to the fish pen in FIG. 20-21, as well as the illustrated connections, are merely examples and are not intended to limit the present disclosure.

[0117] FIG. 22 illustrates a two-stage oxygenator 2200 with back pressure control, according to an exemplary embodiment of the present disclosure. As shown in FIG. 22, the two-stage oxygenator 2200 includes an oxygen supply line 2205 that supplies oxygen to a head space zone 2245. A water pump 2215 located on a platform 2220 draws water through an inlet 2240 and supplies water to a submerged zone 2230 of the two-stage oxygenator 2200 via a water line supply 2210. The submerged zone 2230 then supplies a spray nozzle 2235 that generates a water spray 2255. The water spray 2255 enters an air bubble entrainment zone 2260 above a quiescent zone 2270. As can be seen from the figure, the two-stage oxygenator 2200 has two airtight chambers separated by a baffle wall 2265. A float operated off-gas release valve 2250 is fixed to the side of the two-stage oxygenator 2200 near the head space zone 2245 to relieve pressure if necessary. The two airtight chambers are joined by a blending zone 2285 at the end 2275 of the baffle wall 2265. A discharge line 2290 is connected to the blending zone 2285 to output treated water 2297 through a back pressure valve 2295.

[0118] The blending zone 2285 allows water with different dissolved oxygen levels produced by different stages or chambers to be mixed before being delivered to the user area. The blending zone 2285 may have a rounded bottom to accommodate internal pressures that may exceed local hydrostatic pressure at certain depths. The backpressure valve 2295 may be manually or remotely actuated using a motorized assembly. For example, the water depth at a site may be limited to 20 feet, but a performance level representing 35 feet may be desired (performance increases with pressure). Thus, the backpressure valve 2295 may be actuated to generate a backpressure increase in the reactor of 15 feet. As can be appreciated, the backpressure may also be adjusted as needed.

[0119] As can be appreciated, the two-stage oxygenator 2200 of FIG. 22 may use a non-submersible pump for the water pump 2215, which may be mounted on a platform 2220, which may be, for example, a barge or other surface structure. The use of a discharge valve allows for restricting water exiting the reactor and increasing pressure within the reactor to enhance gas diffusion. This is particularly advantageous in areas where water depth is limited and higher gas transfer rates are desired. Of course, this option also increases head loss throughout the system, thus making the pump work harder for a target value of water flow rate. Thus, a float-actuated off-gas release valve 2250 is used to maintain the target water level within the reactor. The use of a non-submersible pump reduces costs and allows for easier repair and maintenance. The line 2210 supplying water to the two-stage reactor may be flexible to accommodate wave operation. For simplicity, only a two-stage reactor is shown, but additional stages are possible without departing from the scope of this disclosure.

[0120] While the description herein focuses primarily on oxygen saturation of water for simplicity, those skilled in the art will recognize that the described devices and methods are equally capable of supersaturating water with carbon dioxide.

[0121] Obviously, many modifications and variations are possible in light of the above teachings, and it is therefore to be understood that, within the scope of the appended claims, the embodiments of the present disclosure may be practiced otherwise than as specifically described herein.

[0122] Thus, the foregoing description discloses and describes merely exemplary embodiments of the present disclosure. As will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from the spirit thereof. Accordingly, the disclosure of the present disclosure is intended to be illustrative and not limiting of the disclosure, as well as other claims. The disclosure, including any readily discernible variations of the teachings herein, defines, in part, the scope of the terms of the preceding claims such that the subject matter of the invention is not dedicated to the public.

Claims

1. 1. A multi-stage oxygenator system comprising: a fluid-tight pressure vessel configured to be immersed and including a first section, a second section, and a third section; at least one baffle configured to divide the second section of the pressure vessel into two or more compartments; a water delivery mechanism configured to deliver water through the first section of the pressure vessel to the second section of the pressure vessel, the first section of the pressure vessel including a junction between the first section of the pressure vessel and the second section of the pressure vessel, the junction delivering the water as water jets or droplets to the two or more compartments in the second section of the pressure vessel to create a flooded zone in the two or more compartments, the flooded zone being filled with the water; and a gas delivery mechanism configured to deliver a gas to a first of the two or more compartments to create a first gas gap in the first of the two or more compartments, the gas comprising oxygen, the first gas gap being disposed between the first section of the pressure vessel and a flooded zone of the first of the two or more compartments, and the water jets or droplets fall through the first gas gap onto a first free surface of the flooded zone of the first of the two or more compartments; a gas connection through the at least one baffle configured to allow gas to travel from at least the first one of the compartments to at least a second subsequent compartment in series therewith; a gas release device disposed on a side of the second section of the pressure vessel and configured to release gas from a last one of the compartments in series, the gas release device being positioned at a designated location within the compartment to maintain the first gas void and the second gas void at a predetermined volume; a water discharge port in the third section of the pressure vessel configured to output treated water from the pressure vessel; the third section of the pressure vessel connects the two or more compartments of the second section to allow water from the flooded zones of the two or more compartments to mix and produce the treated water; A multi-stage oxygenator system, wherein the multi-stage oxygenator system is configured to be secured and stabilized at a predetermined depth.

2. 2. The multi-stage oxygenator system of claim 1, wherein the junction between the first section and the second section of the pressure vessel includes a plate having a plurality of openings for forming the water jets.

3. The water delivery mechanism comprises: a pipe disposed at a center of the pressure vessel and extending through the first section, the second section, and the third section; a manifold connected to the junction between the pipe and the first section and the second section of the pressure vessel; the pipe is configured to deliver the water to the manifold, and the manifold is configured to deliver the water to each of the two or more compartments through the junction between the first section and the second section of the pressure vessel; 3. The multi-stage oxygenator system of claim 1 or 2, wherein the at least one baffle is attached to the pipe and an interior wall of the pressure vessel to create the two or more compartments within the second section of the pressure vessel.

4. the first section of the pressure vessel includes a chamber configured to be flooded with water by the water delivery mechanism; The joint between the first section and the second section of the pressure vessel comprises: a plurality of openings for forming the water jets to deliver the water to the two or more compartments at a predetermined water pressure; or at least one nozzle for forming the water droplets to deliver the water to the two or more compartments at the predetermined water pressure; 10. The multi-stage oxygenator system of claim 1, comprising a plate having one of:

5. the gas release device includes one of a float valve or an off-gas vent; 5. The multi-stage oxygenator system of claim 1, wherein the off-gas outlet comprises a connector connected to the pressure vessel, a right angle coupling connected to the connector, and a tube connected to the right angle coupling, an open end of the tube defining the location of the free surface of the flooded zone of the two or more compartments.

6. 6. The multi-stage oxygenator system of claim 1, wherein the water outlet port is coupled to a pressure control valve configured to maintain the pressure vessel at a predetermined pressure.

7. 7. The multi-stage oxygenator system of claim 6, wherein said predetermined pressure regulates oxygen exchange from said gas to said water and promotes nitrogen removal from said water, said predetermined pressure preferably simulating a depth of 100 feet.

8. 8. The multi-stage oxygenator system of claim 7, wherein reactor off-gas containing oxygen and nitrogen is discharged from all of said two or more compartments of said second section of said pressure vessel via gas release valves.

9. 9. The multi-stage oxygenator system of any one of claims 1 to 8, wherein the pressure vessel is secured in place and stabilized via at least one of a ballast and mooring structure or a pipe riser configured to deliver the water to the water delivery mechanism.

10. 10. The multi-stage oxygenator system of claim 9, further comprising a submersible pump attached to said pipe riser for pumping water through said pipe riser and into said water delivery mechanism, said pump forming at least a portion of said ballast for stabilizing said multi-stage oxygenator.

11. said water jets or droplets impacting said first and second free surfaces of said two or more compartments to form an air bubble entrainment zone within each of said two or more compartments; 11. The multi-stage oxygenator system of claim 1, wherein a quiescent zone is disposed between the bubble entrainment zone and the third section of the pressure vessel in each of the two or more compartments, and wherein gas bubbles in the water of the quiescent zone bind and rise to a respective one of the first free surface and the second free surface and thereafter to a respective one of the first gas void and the second gas void.

12. a pump coupled to the water delivery mechanism and configured to pump the water from a water source to the water delivery mechanism; a screen coupled to an inlet of the pump and configured to screen solids from the water; 12. The multi-stage oxygenator system of any one of claims 1 to 11, wherein the water source is fresh water or salt water.

13. 13. The multi-stage oxygenator system of claim 1, further comprising at least a second baffle oriented perpendicular to the at least one baffle and configured to separate downwardly flowing air bubbles in the submerged zone of at least one of the at least two or more compartments from upwardly flowing air bubbles in the at least one of the two or more compartments, the second baffle being attached to an interior wall of the pressure vessel.

14. 14. The multi-stage oxygenator system of any one of claims 1 to 13, further comprising a vent for venting gas from the pressure vessel during at least one of installation, maintenance, and removal of the pressure vessel.

15. The water delivery mechanism comprises: at least one distribution plate having a predetermined number of orifices distributed within one or more zones of said at least one distribution plate and no orifices within at least one remaining zone of said at least one distribution plate; the water flows through the orifices in the at least one distribution plate into the two or more compartments; the orifices in the at least one distribution plate are arranged in dual rows to form groups of orifices separated by gaps not including an orifice; 15. The multi-stage oxygenator system of claim 1, wherein the orifices are positioned to cover a predetermined amount of linear area based on hydraulic loading corresponding to a given application of the multi-stage oxygenator system.

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