Patent Publication Number: US-11660576-B2

Title: High-flow, high-pressure inline saturator system and method thereof

Description:
TECHNICAL FIELD 
     The invention relates generally to systems and a method that dissolve gas into a liquid and, more particularly, to inline saturator systems for use in aquaculture. 
     BACKGROUND 
     Whether dealing with fish, shell fish, or crustaceans in the aquaculture and wild fisheries industry, it is critical to be able to control the dissolved gas environment in the associated water. In general, there are two issues that must be controlled: maintaining sufficient dissolved oxygen for respiration, and removing the dissolved carbon dioxide resulting from respiration. 
     It is generally understood that higher levels of dissolved oxygen in the water have a positive influence on the health and growth rate of fish. Within the aquaculture industry, the usual approach to maintaining dissolved oxygen levels involves the injection of oxygen gas through one or more high-pressure venturi nozzles. 
     While this approach is viable, it also increases the total gas pressure, which in turn, tends to cause the oxygen to bubble out of the water. It is also known that the overall dissolved gas pressure can play a significant role in fish health and growth rate, etc. As such, a further issue concerns the fact that prolonged exposure to an elevated total gas pressure can be a health hazard to the biomass in the water. 
     SUMMARY 
     This disclosure provides an inline saturator system for gas exchange with an aqueous-phase liquid, the system comprising: 
     a pressure vessel configured to receive a first liquid and a first gas from external sources, and to discharge a second liquid and a second gas from the pressure vessel; 
     a gas infusion device situated within the pressure vessel, the gas infusion device configured to receive the first liquid and first gas, to facilitate gas exchange between the first liquid and first gas, producing the second liquid and the second gas, and to discharge the second liquid and second gas into the pressure vessel; and 
     a recirculation system configured to redirect a portion of liquid within the pressure vessel back into the saturator device; 
     wherein injection of the redirected liquid into the gas infusion device forces the first liquid into the gas infusion device for the gas exchange. 
     This disclosure also provides a method for gas exchange with an aqueous-phase liquid, the method comprising: 
     injecting a first liquid and a first gas into a pressure vessel; 
     directing the first liquid and the first gas through a gas infusion device situated within the pressure vessel, the gas infusion device configured to facilitate gas exchange between the first liquid and the first gas, producing a second liquid and a second gas; 
     redirecting a portion of the second liquid back into the saturator device; and 
     discharging the remaining second liquid out of the pressure vessel; 
     wherein the redirection of the second liquid into the gas infusion device draws the first liquid into the gas infusion device for the gas exchange. 
     Advantages and features of the invention will become evident upon a review of the following detailed description and the appended drawings, the latter being briefly described hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made, by way of example, to the accompanying drawings which show an example of the present application, in which: 
         FIG.  1    is a plan view of a saturator system according to an example of the present invention with access doors in the open position; 
         FIG.  2    is a front view of the saturator system of  FIG.  1    with the internal components shown in dashed lines and the access doors in the closed position; 
         FIG.  3    is a right side view of the saturator system of  FIG.  2    with the internal components shown in dashed lines; 
         FIG.  4    is a schematic view of the saturator system of  FIG.  2   ; 
         FIG.  5    is a cross-sectional, plan view of the saturator system of  FIG.  4    along line  5 - 5 ; 
         FIG.  6    is a plan view of a double array saturator system according to another example of the present invention with access doors in the open position; 
         FIG.  7    is a front view of the saturator system of  FIG.  6    with the internal components shown in dashed lines and the access doors in the closed position; 
         FIG.  8    is a left side view of the saturator system of  FIG.  7    with the internal components shown in dashed lines; 
         FIG.  9    is a sample graph explaining the elements of the graphs in the subsequent Figures. 
         FIGS.  10 - 28    show oxygen percent saturation graphs using the saturator system of  FIG.  6   . 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS SHOWN IN THE DRAWINGS 
     An example embodiment of a saturator system  10 , a double array saturator system  100 , and methods of their use will be discussed. Saturator system  10  will first be described. 
     Saturator System 
     As shown in  FIGS.  1 - 6   , saturator system  10  generally includes a pressure vessel  12 , two saturation devices  14 , a recirculation system  16 , and a control system. 
     Pressure vessel  12  in this example embodiment is generally cylindrical in shape, having a 2.15 meter length with a diameter of 0.61 meters. Pressure vessel  12  comprises an input port  18  situated in the middle of pressure vessel  12  for receiving a first liquid from an external source and an output port  20  for discharging a second liquid that is different from the first liquid, from pressure vessel  12 . Output port  20  is positioned below input port  18 , external to pressure vessel  12 . Overall, saturator system  10  has a height of about 1.023 meters. 
     Input port  18  is covered by a shut-off valve (not shown) and downstream from input port  18  is positioned a flow rate sensor  22  for monitoring the flow of the first liquid into pressure vessel  12 . Output port  20  is also covered by a back-pressure control valve  24  positioned upstream of output port  20  for maintaining fluid pressure within pressure vessel  12 . Both input port  18  and output port  20  each have a diameter of about 0.203 meters. 
     Pressure vessel  12  includes a gas inlet  26  for receiving a first gas, and a gas outlet  28  for discharging a second gas, that is different from the first gas, from pressure vessel  12 . Gas inlet  26  is further in fluid communication with gas manifolds  27  situated within pressure vessel  12 . Gas manifolds  27  are situated adjacent to and are in fluid communication with saturator devices  14 . Saturator device  14  is also referred herein to as a gas infusion device. 
     Gas outlet  28  in the depicted embodiment includes an air eliminator  30  and a pressure relief valve  32 , both in fluid communication with pressure vessel  12 . Both are adapted to transfer gas from within pressure vessel  12  to the atmosphere. 
     Pressure vessel  12  is made of a steel alloy, particularly 316 stainless steel, to enable it operate in a salt-water environment. Further, pressure vessel  12  is an ASME-certified pressure vessel, rated for an operating pressure of 100 psi. 
     Pressure vessel  12  has two pressure-rated doors  34  with seals. Doors  34  cover openings on opposed sides of pressure  12 , through which a user may access the internal space within pressure vessel  12  for cleaning and maintaining of components inside pressure vessel  12 . 
     A mechanical means, or a baffle  36 , is further situated within pressure vessel  12 . Baffle  36  is adapted to mechanically direct the first liquid from input port  18  to saturator devices  14 . 
     Saturator devices  14  are situated within pressure vessel  12  and are positioned on either side of input port  18 , orientated generally parallel with one another. Each gas infusion device  14  has a first end portion  38 , for receiving the first liquid and discharging the second gas, and an opposed second end portion  40  for receiving the first gas and discharging the second liquid into pressure vessel  12 . Each gas infusion device  14  further has a fibre module array  42  situated between the end portions where fibre module array  42  is made up of a polymer coated microporous fiber material. In the present embodiment, saturator devices  14  are the saturator or gas infusion device disclosed in U.S. Pat. No. 7,537,200, to Glassford, Oct. 31, 2003. 
     Recirculation system  16  includes a suction nozzle  44  and two discharge nozzles  46 , which are all in fluid communication with pressure vessel  12 . 
     Suction nozzle  44  is positioned proximate second end portion  40  of gas infusion device  14  to draw a portion of liquid into recirculation system  16 . One discharge nozzle  46  is positioned adjacent each first end portion  38  of each gas infusion device  14  to inject the portion of liquid back into gas infusion device  14 . 
     Recirculation system  16  includes a pump  48  (see  FIGS.  6 - 8   ) operatively coupled between suction nozzle  44  and discharge nozzles  46 , pump  48  being adapted to drive fluid from suction nozzle  44  to discharge nozzles  46 . 
     Recirculation system  16  further includes two eductors  50 , one eductor  50  operatively coupled between each discharge nozzle  46  and its corresponding gas infusion device  14 . 
     Eductors  50  are made of metal, and in the present embodiment, made of 316 stainless steel. In this manner, eductors  50  are adapted to operate in a high-pressure, salt-water environment. 
     The control system (not shown) is operatively coupled to the flow rate sensor  22  and back-pressure control valve  24 . The control system further includes a pressure sensor  52  situated within pressure vessel  12 , which is adapted to measure the fluid pressure within pressure vessel  12 , and a regulator (not shown) on gas inlet  26 . 
     Saturator system  10 , has mounts  54  fixed to, and extending from, pressure vessel  12 . Mounts  54  are mechanical means which allow saturator system  10  to be secured to the ground, a vertical wall and/or to another saturator system  10  as described below. 
     Whereas a specific embodiment of saturator system  10  is herein shown and described, variations are possible. In some examples, pressure vessel  12  contains two or more gas inlets  26 , two or more air eliminators  30 , and/or two or more suction nozzles  44 . 
     In other examples, rather than a two saturator devices  14 , pressure vessel  12  may instead house one or more than two saturator devices  14 . 
     As well, instead of the saturator devices being positioned side-by-side and orientated parallel with one another in an upright position (i.e. linear horizontally) within pressure vessel  12 , in other examples, the multiple saturator devices  14  are oriented in one of the following ways: linear vertical, planar horizontal, planar vertical, or arbitrarily. 
     In other examples, rather than using a single pump, saturator system  10  includes two or more pumps as part of its recirculation system  16 . 
     Double Array Saturator System 
     As shown in  FIGS.  6 - 8   , double array saturator system  100  generally includes two saturator systems  10  with a shared recirculation system  16  and a common pump  48 . Mounts  54  allow one pressure vessel  12  to be secured on top of or above the other pressure vessel  12 . 
     In the shown embodiment, each pressure vessel  12  houses two saturator devices  14  therein. Each pressure vessel  12  also has its own corresponding suction nozzle  44  and two discharge nozzles  46 , which are all in direct fluid communication with pump  48 . 
     Whereas a specific embodiment of double array saturator system  100  is herein shown and described, variations are possible. 
     In some examples, each pressure vessel  12  and saturator devices  14  may be varied as noted above. 
     In others examples, instead of pressure vessels  12  being positioned one on top of the other in parallel (i.e. linear vertically), in other examples, the multiple pressure vessels  12  are oriented in one of the following ways: linear horizontal, planar horizontal, planar vertical, or arbitrarily. 
     Double array saturator system  100  may instead have two recirculation systems  16  (with a pump  48  each), one operatively coupled to each pressure vessel  12 . 
     Independent Use 
     Both saturator system  10  and double array saturator system  100  are for use in conducting a gas exchange with an aqueous-phase liquid inline with a tank of water. While the tank is not shown, both saturator system  10  and double array saturator system  100  are understood to be coupled to the tank with piping extending from their input ports  18  and output ports  20 . Movement of liquid through the use of systems  10  and  100  are indicated by dashed arrows in the Figures. While not shown in the drawings, the saturator systems may also be used in a contained, open body of water. 
     The first liquid is injected into pressure vessel  12  through input port  18 , and directed towards first end portion  38  of saturator devices  14  by baffle  36 . The first gas is also injected into vessel  12  through gas inlet  26  and directed to gas manifolds  27 , which are adjacent second end portion  40  of each gas infusion device  14 . 
     Simultaneously, a portion of fluid that is proximate second end portion  40  of gas infusion device  14  is drawn by pump  48  through suction nozzle  44 . The portion of fluid is redirected and pumped through discharge nozzles  46  and through eductors  50 , which are positioned adjacent first end portion  38  of saturator devices  14 . The force of the redirected fluid as it travels through eductor  50  draws and drives the first liquid into first end portion  38  of gas infusion device  14 . 
     In gas infusion device  14 , the first liquid and the first gas interact with the fibre module array, which facilitate a gas exchange between the first liquid and first gas as both fluids travels through gas infusion device  14 . This exchange produces the second liquid and the second gas, which are both discharged from second end portion  40  of gas infusion device  14  into the pressure vessel. 
     While most of the second liquid will be then discharged from pressure vessel  12  through output port  20 , some of the second liquid will be drawn by pump  48  through suction nozzle  44  into recirculation system  16 . This liquid is then redirected to first end portion  38  of gas infusion device  14  through discharge nozzle  46 . This redirected second liquid will then be pumped through eductor  50  and used to draw the first liquid into gas infusion device  14  for the gas exchange. 
     As noted above, both saturator system  10  and double array saturator system  100  are adapted for operation under pressure. In that regard, the control system uses information from flow rate sensor  22  and pressure sensor  52  to maintain the pressure within pressure vessel  12  at a predetermined level. The control system drives back pressure control valve  24  and pump  48  in order to maintain sufficient head to drive fluid through gas infusion device  14  and to maintain fluid pressure under low-flow conditions. In the present embodiment, the control system drives pump  48  so as to ensure that the pressure in gas infusion device  14  is at least 20 psi. 
     The control system also uses information from flow rate sensor  22  to determine the amount of the first gas required by each gas infusion device  14 . The control system controls the regulators connected to gas inlets  26  on pressure vessel  12 . The control system may be configured to detect the vibration of pump  48  in order to monitor the pump&#39;s mechanical health. 
     In order to maintain a generally stable total gas pressure, the second gas is released through air eliminator  30  to the atmosphere. For safety, pressure relief valve  32  may also be used to further release gases from pressure vessel  12  into the atmosphere. 
     Whereas a specific embodiment of the method is herein shown and described, variations are possible. 
     In other examples, the control system drives pump  48  may be adapted to ensure that the pressure in saturator system  10  is up to 65 psi. 
     Combined Use 
     Both saturator system  10  and double array saturator system  100  may be used simultaneously with one or more lift pumps situated within the body of water. 
     The lift pumps are configured to remove carbon dioxide gas from the water. An example of such a lift pump is disclosed in U.S. 62/607,385. Each lift pump includes a gas input and perforations to enable water to enter the lift pump. 
     The perforations are situated on a plate for gas to pass through, where the plate positioned upstream from a mixing chamber, through which water enters the lift pump and where the gas forms bubbles which improve gas lift. The perforated plate is made by additive manufacturing with precise hole dimensions and hole spacing. 
     As the gas is bubbled into the water through the plate, it reduces the water density so that the water rises through the lift pump, thus enabling more water to enter through the perforations. As the water rises, dissolved CO 2  in the water is exchanged with the injected air based on Henry&#39;s Law, such that the partial pressure of dissolved CO 2  in the water will work to match the partial pressure of CO 2  in the air. 
     Used together in this manner, the saturator system oxygenates the body of water, while the one or more lift pumps remove the dissolved CO 2  and remediates the ammonia to form nitrate. 
     Such a system may further include one or more oxygen tanks connected to the saturator system for supplying oxygen to the saturator system, and a compressor coupled to lift pumps to supply ambient air to generate the lift. 
     Such a system may also have a gas regulator operatively coupled between the oxygen tanks and the saturator system to regulate the flow of gas into the saturator system, a dissolved oxygen sensor positioned within the body of water, a saturator feed pump in fluid communication with the body of water, adapted to draw and direct water from the body of water into the saturator system, and an ammonia sensor positioned within the body of water. 
     A control and monitoring system may be in place to communicate with, control and coordinate each of the above components. For example, the compressor can be activated to engage the lift pumps in response to the detected concentration of ammonia rising above a maximum level. The compressor may then be disengaged to deactivate the lift pumps in response to the detected concentration of ammonia falling below a minimum level. In a similar manner, the gas regulator and the saturator feed pump may be activated and controlled in response to the detected concentration of oxygen falling below a minimum level. The gas regulator and the saturator feed pump may also be deactivated accordingly. 
     Whereas a specific embodiment of the method is herein shown and described, variations are possible. 
     Testing 
     The following tests were conducted. The first gas used was oxygen and the first liquid was oxygen-poor and carbon dioxide-rich saltwater or oxygen-poor and carbon dioxide-rich freshwater. 
     Requirements 
     
         
         
           
             Tank of water 
             Discharge Pipes 
             Suction pipe 
             Recirculation pump 
             Pressure control valve 
             Variable speed pump(s) 
             Oxygen source 
             Measuring equipment (Oxygen, total gas pressure, temperature, Salinity, pressure, Oxygen flow, water flow) 
           
         
       
    
     The tests were set up by connecting the suction and discharge pipes, respectively, to the inlet port and the outlet port of the saturator system, the other ends of the pipes were placed in the tank of water, on opposite sides of the tank to ensure good circulation of oxygenated water. The pressure control valve is positioned between the saturator system and the discharge pipe to the tank. 
     Background measurements of the water tank were taken, noting salinity, temperature, total gas pressure and oxygen readings. 
     A small amount of oxygen is fed to the unit to keep the fibers of the saturator devices clear of water. 
     The variable speed pumps are then turned on to allow water from the tank to flow into and fill the pressure vessel and the pipes. 
     The pressure control valve is partially closed to increase the pressure within the pressure vessel to the desired level. 
     By adjusting the water flow and pressure within the pressure vessel, the desired predetermined parameters are eventually achieved. The parameters for the trials are set out in Table 1 below. 
     The recirculation pump is then turned on and increased until there is at least 30 PSI differential between the recirculation pump pressure and the unit pressure. 
     The oxygen is turned on at the desired level. 
     The saturator system was then run for the predetermined desired time. 
     The saturator system is then shutdown in reverse order, i.e. first the oxygen is turned off, then the recirculation pump, and then pressure. 
     Readings are taken for oxygen, temperature, and total gas pressure and compared to the previous values. Previous values are those of water at sea level, that being 100% oxygen saturation, 15 Degrees C., at 760 mmHg (100% total gas pressure). If the tank did not mix properly, several locations will have to be measured to get a full profile on the tank. 
     Based on these comparisons, it was determined how much oxygen was added to the water and how much other gas was removed. 
     A number of tests were run according to the following rationale, and the results illustrated in the noted Figures. 
       FIG.  9    is a sample graph explaining the elements of the graphs in the subsequent Figures.
         A: Point at which the pump was turned on   B: Trial name indicating salinity, pressure in pounds per square inch, water flow in liters per minute and Oxygen flow in liters per minute (corrected for pressure)   C: Calculated grams of oxygen infused per minute   D: The theoretical value that should be obtained based on our internal models   E: Actual Oxygen percent saturation readings   F: Time during which Oxygen was added       

       FIGS.  10 - 28    show percent saturation data using the saturator system of  FIG.  6   .
         Trial 1: This test was preformed as a first attempt to replicate the most basic function of the unit in fresh water (FW) to see if it compared favorably to the models. See  FIG.  10   .   Trial 2: This test was preformed as an attempt to replicate the most basic function of the unit in fresh water at an known operating pressure for smaller units. See  FIG.  11   .   Trial 3a: This test was preformed to see if there was an issue with the right array. See  FIG.  12   .   Trial 3b: This test was preformed to see if there was an issue with the left array. See  FIG.  13   .   Trial 4: This test was preformed at an increased differential pressure in the arrays and an account taken for the volume of piping in the experiment. See  FIG.  14   .   Salt water (SW) trial 1: This test was preformed as a first attempt to replicate the most basic function of the unit in salt water at an increased differential to see if it compared favorably to the models. See  FIG.  15   .   SW trials 2, 3, 5, 7, 8, 9, 10, and 11: These trials were performed to push the limits of the device and see how accurate our current modeling system reflected reality in salt water. See  FIGS.  16 - 23   .   FW trials 1-5: These trials were performed to push the limits of the device and see how accurate our current modeling system reflected reality in fresh water. See  FIGS.  24 - 28   .       

     The outcome for the salt water and fresh water trials (corresponding to  FIGS.  15 - 27   ) are also summarized in Table 1 below. 
     The tests show that levels of oxygen could be infused at levels not previously possible with conventional equipment while keeping the total gas pressure (TGP) relatively unchanged. For example, in Saltwater trial 11, the saturator system was operated at 65 internal psi, with water flow at 8000 L/min and oxygen flow at 245 L/min. While dissolved oxygen levels reached 447 percent saturation, the overall total gas pressure change was only 6.5 percent. 
     In comparison, existing saturator devices can only dissolve oxygen in water to reach 300 percent saturation, while the overall total gas pressure change is usually 140 percent, which is lethal to aquatic life. 
     As such, an advantage of the use of the present saturator system  10  and/or double array saturator system  100  is that the oxygen could be infused into the water at nearly ten times the amount of oxygen that would be infused by using the prior art saturator device while the total gas pressure in the liquid remains relatively unchanged. 
     Another advantage of the present saturator system is that it enables gas to be infused into an aqueous liquid under pressure with a high flow rate without increasing or significantly increasing the total gas pressure in the liquid. 
     The invention should be understood to be limited only by the accompanying claims, purposively construed. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                 Water 
                 Back 
                   
                   
                 Recirc 
                   
                 Oxygen 
                 Oxygen 
                   
                   
                   
               
               
                 Trial 
                   
                 Temp 
                 Flow 
                 Pressure 
                 Rotameter 
                 Oxygen 
                 Pressure 
                 Target O2 
                 Delivered 
                 Delivered 
                 % TGP 
                 Efficiency 
                 Final 
               
               
                 # 
                 FW/SW 
                 (C.) 
                 (LPM) 
                 (psi) 
                 (LPM) 
                 (LPM) 
                 (psi) 
                 (gm/min) 
                 (gm/min) 
                 (LPM) 
                 Change 
                 % 
                 % DO 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 Apr. 16-19, 2018 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 SW 
                 19.17 
                 3000 
                 17.5 
                 21 
                 60 
                 47.5 
                 64.6 
                 67 
                 46.8 
                 6 
                 78 
                 208 
               
               
                 2 
                 SW 
                 17.34 
                 3200 
                 21.5 
                 22.8 
                 70 
                 51.5 
                 82.6 
                 87.8 
                 61.4 
                 3.25 
                 87.7 
                 231 
               
               
                 3 
                 SW 
                 17.08 
                 3400 
                 26 
                 24.6 
                 80 
                 56 
                 97.1 
                 102 
                 71.3 
                 4.3 
                 89.1 
                 240 
               
               
                 5 
                 SW 
                 10.24 
                 3800 
                 30.3 
                 29.3 
                 100 
                 61 
                 124.5 
                 130.2 
                 91.1 
                 4.5 
                 91.3 
                 253 
               
               
                 7 
                 SW 
                 17.28 
                 4000 
                 36.85 
                 31.5 
                 115 
                 67 
                 140.4 
                 133.3 
                 93.2 
                 3.4 
                 81.1 
                 268 
               
               
                 8 
                 SW 
                 16.91 
                 4000 
                 43.25 
                 33.5 
                 130 
                 74 
                 161.7 
                 154.6 
                 108.1 
                 2.85 
                 83.2 
                 294 
               
               
                 9 
                 SW 
                 11.44 
                 4500 
                 52 
                 38.5 
                 160 
                 85 
                 208.7 
                 186.4 
                 130.4 
                 3.05 
                 81.5 
                 307 
               
            
           
           
               
            
               
                 May 2-4, 2018 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 FW 
                 11.3 
                 4000 
                 30.35 
                 17.6 
                 60 
                 90 
                 66 
                 68 
                 47.6 
                 6 
                 79.3 
                 173 
               
               
                 2 
                 FW 
                 11.6 
                 6000 
                 34.7 
                 20 
                 70 
                 92 
                 90 
                 99 
                 69.2 
                 3.5 
                 98.9 
                 191 
               
               
                 3 
                 FW 
                 12.1 
                 8000 
                 45.5 
                 22 
                 85 
                 100 
                 113.1 
                 112.3 
                 78.5 
                 4.5 
                 98.1 
                 209.4 
               
               
                 4 
                 FW 
                 12.5 
                 8000 
                 45.1 
                 31.8 
                 125 
                 100 
                 125 
                 152 
                 106.3 
                 9 
                 85.1 
                 244 
               
               
                 10 
                 SW 
                 19.1 
                 6000 
                 52 
                 45.7 
                 190 
                 90 
                 210 
                 225 
                 157.4 
                 7 
                 82.8 
                 354 
               
               
                 11 
                 SW 
                 19.2 
                 8000 
                 65 
                 53.9 
                 245 
                 105 
                 265 
                 295 
                 206.3 
                 6.5 
                 91.7 
                 447