Abstract:
Provided herein are systems, apparatus, and methods for extracting pure oxygen from a liquid. In some embodiments, a system for extracting oxygen from a liquid comprises a separator configured to allow a liquid to pass therethrough and to produce a liquid mixture comprising the liquid having at least a portion of oxygen removed therefrom. The separator comprises a wall surrounding an interior portion of a tube, the wall having at least one aperture formed therein. The separator also comprises at least one magnet positioned adjacently to the at least one aperture having a north pole end and a south pole end forming a magnetic field gradient therebetween and extending into an interior portion of the tube. The system also comprises a storage tank fluidly coupled to the at least one aperture and configured to store the at least a portion of oxygen removed from the liquid via the separator.

Description:
RELATED APPLICATIONS 
       [0001]    This application hereby claims the benefit of and priority to U.S. Provisional Patent Application 62/299,286, titled “SYSTEM AND A METHOD TO EXTRACT OXYGEN FROM AIR,” filed Feb. 24, 2016, and which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    Aspects of the disclosure are related to oxygen extraction and more particularly to extracting oxygen from air. 
       TECHNICAL BACKGROUND 
       [0003]    Pure oxygen is useful in many ways. Fields that benefit from the use of pure oxygen include, for example, the medical field, sports and recreational fields, and the industrial field. Pure oxygen, however, is not readily available as a direct source but must instead be extracted from other sources including oxygen. There are various ways to capture or extract pure oxygen from such other sources. Extracting oxygen has typically been expensive and can require a complex setup that limits the supply of oxygen in various industries and fields. 
         [0004]    In non-cryogenic extraction methods, process such as adsorption, chemical processing, polymeric membranes, and ion transport membranes may be used. In the adsorption method, a material made up of special compounds is used that has unique capabilities for adsorbing certain gases such as oxygen, thus removing that gas from a mixture of other gases. The adsorption method does not entail a chemical change in the material, thus allowing for reversible process. However, the complete removal of a specific gas using this process is difficult to achieve with great certainty. Since the process is reversible, an equilibrium state is achieved where the target gas starts flowing out of the adsorbing material. 
         [0005]    By utilizing certain chemical approaches, it is possible to react with the gases and remove certain chemicals directly. This approach can be very effective to achieve 100% purity, since the chemical reaction will keep on happening given enough reactant and sufficient reactive area. Thus, the gas can be completely removed. However, chemical separation approaches can be quite complex to implement and do not currently present meaningful market share. Furthermore, creating continuous systems based on chemical approaches is difficult. 
         [0006]    By filtering air through a permeable membrane such that the membrane has higher permeability to oxygen than another gas (such as nitrogen), the concentration of oxygen can be increased by trapping or filtering the other, larger gas. This technique, however, does not typically achieve a high purity in the target gas because, as a separator, the filter will allow gases that are more permeable than the target gas to pass through unimpeded. Thus, the resultant gas includes a mixture of all of the gases more permeable than what the filter can remove. 
         [0007]    The ion transport membrane method uses hot liquid gases (that would ionize oxygen) passing over special (ceramic) membranes that allow the oxygen ions to pass through and recombine to create pure oxygen. However, while this process can achieve pure oxygen, it uses high energy costs for heating and for recompressing the recombined oxygen. 
         [0008]    In one cryogenic extraction method, by utilizing pressure and centrifuges, it is possible to separate oxygen from air without liquefaction. However, this process suffers from high energy costs and complex equipment. 
         [0009]    Another cryogenic extraction method takes advantage of the fact that at a certain pressure, every gas has a separate boiling temperature. By gradually reducing the pressure (i.e., relieving the pressure) from on outlet of a liquid air container, every gas will take its turn to exit the tank according to its boiling temperature. This approach is effective at separating all types of gases from each other, but suffers from energy losses at many stages and that the process cannot be done in a continuous mechanism, requiring staging of separate lines for compressing and separation. 
         [0010]    Thus, it would be advantageous to utilize a system of extracting pure oxygen from air that overcomes the aforementioned drawbacks. 
       OVERVIEW 
       [0011]    In one example, a system for extracting oxygen from a liquid comprises a separator configured to allow a liquid to pass therethrough and to produce a liquid mixture comprising the liquid having at least a portion of oxygen removed therefrom. The separator comprises a wall surrounding an interior portion of a tube, the wall having at least one aperture formed therein. The separator also comprises at least one magnet positioned adjacently to the at least one aperture, the at least one magnet having a north pole end and a south pole end forming a magnetic field gradient therebetween and extending into an interior portion of the tube. The system also comprises a storage tank fluidly coupled to the at least one aperture and configured to store the at least a portion of oxygen removed from the liquid via the separator. 
         [0012]    In another example, method of extracting oxygen from liquid air comprises extracting oxygen from liquid air to produce a liquid mixture comprising the liquid air having at least a portion of the oxygen extracted therefrom via passing the liquid air through a separator. The separator includes a wall surrounding an interior portion of a tube, the wall having at least one aperture formed therein. The separator also includes a magnet assembly positioned adjacently to the at least one aperture, the magnet assembly having a north pole and a south pole forming a magnetic field gradient between the north and south poles, wherein the magnetic field gradient extends into an interior portion of the tube. The method further comprises storing the extracted oxygen in a storage tank fluidly coupled to the at least one aperture. 
         [0013]    The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Many aspects of the disclosure can be better understood with reference to the following drawings. While several implementations are described in connection with these drawings, the disclosure is not limited to the implementations disclosed herein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents. 
           [0015]      FIG. 1  illustrates an oxygen extraction system according to one embodiment. 
           [0016]      FIG. 2  illustrates an oxygen extraction system with an additional expansion stage. 
           [0017]      FIG. 3  illustrates a portion of the separator shown in  FIGS. 1 and 2 . 
           [0018]      FIG. 4  illustrates an embodiment of a separator tube shown in a cross-sectional view. 
           [0019]      FIG. 5  illustrates an embodiment of a separator tube shown in an isometric view. 
           [0020]      FIG. 6  illustrates an isometric view of a portion of the separator of  FIG. 3  according to an embodiment. 
           [0021]      FIG. 7  shows an extraction tube according to another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The following description and associated figures teach the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects of the best mode may be simplified or omitted. The following claims specify the scope of the invention. Note that some aspects of the best mode may not fall within the scope of the invention as specified by the claims. Thus, those skilled in the art will appreciate variations from the best mode that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
         [0023]      FIG. 1  illustrates an oxygen extraction system  100  according to one embodiment. System  100  draws gaseous atmospheric air into an air intake  102  and removes humidity from the air in a dehumidifier  104 . Removal of the humidity from the input air removes water vapor from the air that could easily freeze and block the process or reduce its efficiency. After drying the air in dehumidifier  104 , system  100  compresses the air in a compressor  106 . A motor  108  is configured to run compressor  106  to compress the gaseous air into a liquid state. 
         [0024]    After being compressed into a liquid, the liquid air passes through a separator  110  designed to extract oxygen from the other liquid gases of the liquid air. As described below, separator  110  functions magnetically to draw the liquid oxygen from the liquid air passing through a shaped tube. The extracted liquid oxygen in this embodiment is stored in an oxygen storage tank  112  fluidly coupled to separator  110  to store the oxygen in its liquid state. The process of extracting at least a portion of the oxygen from the liquid air flowing through the separator  110  produces a liquid mixture of the liquid air having at least a portion of oxygen removed therefrom. This liquid mixture flows from the separator  110  to an expander  114  configured to expand the liquid gases into a gaseous state for ejection back into the environment through a gas outtake  116 . Air intake  102  and gas outtake  116  are preferably positioned far away from each other to avoid the less-oxygenated exit air from being drawn back into oxygen extraction system  100 . 
         [0025]    As illustrated, heat generated in the compression stage via compressor  106  and in the separation stage via separator  110  is provided to expander  114  in the expansion stage. In turn, mechanical energy generated in the expansion stage is provided back to the compression stage. In this way, the shared heat and energy between the compression and expansion stages reduces the amount of external work needed to be entered into the system  100  and reduces the amount of external cooling needed to compress the intake gas. Motor  108  is provided to add mechanical energy to maintain the process continuously to overcome any energy losses in the heat and mechanical energy transfer between the stages. If needed, it is contemplated that a cooling subsystem may be incorporated to compensate for heat generated by the system  100 . 
         [0026]    The separation of oxygen from the liquid air via separator  110  in the separation stage may not completely remove all of the oxygen from the liquid air. Instead, a liquid mixture produced by separator  110  as its output may only have a portion of the oxygen removed. Accordingly, it is contemplated that system  100  may include a feedback system  118  coupled to the separator  110  to pass the liquid mixture of gases back through separator  110  one or more additional times to further extract remaining oxygen from the liquid air. Each subsequent pass of the liquid mixture produced by separator  110  is intended to remove more oxygen therefrom, thus increasing the efficiency of the system  100  in removing the oxygen. 
         [0027]      FIG. 2  illustrates an oxygen extraction system  200  with an additional expansion stage. System components in common with system  100  are described above. In the embodiment shown, another expander  202  fluidly coupled to separator  110  is included and coupled to the oxygen output of separator  110  to take advantage of expanding the liquid oxygen back to its gas state to recoup more of the energy of compression and extract extra heat from the compression process. Oxygen storage tank  112  is fluidly coupled to expander  202  to store the oxygen in its gaseous state. In expander  202 , the capture of energy produced via the compression and expansion stages is leveraged. Both expanders  114 ,  202  transfer mechanical energy back to the compressor  106  and receive heat therefrom. 
         [0028]    In a typical concentration of air, the following gases and percentages are found: nitrogen (78.09%), oxygen (20.95%), argon (0.93%), carbon dioxide (0.03%), and water vapor (varies). The magnetic property of oxygen is paramagnetic while the magnetic properties of nitrogen, argon, carbon dioxide, and water vapor is diamagnetic. Accordingly, oxygen molecules are effectively attracted to magnetic fields while the molecules of these other gases are effectively repelled by magnetic fields. The extraction of liquid oxygen from the liquid air in embodiments herein is done by using the paramagnetic property of oxygen. 
         [0029]    By applying a magnetic field gradient to the liquid oxygen, the oxygen separates from the other diamagnetic gases. Depending on the strength gradient of the magnetic field, the oxygen is separated with more or less speed. The larger the magnetic field gradient, the greater the efficiency at separating the oxygen. Magnetic field gradients much greater than 1 Tesla/meter are preferred. Permanent magnets of 1 Tesla (1 T) are commonly available today using available neodymium magnets that can reach an extreme field of 1.4 T, for example. However, merely placing a 1 T magnet next to liquid air will not create a large gradient on its own. To achieve the large gradient magnetic gradient, special arrangements of the magnets is used. 
         [0030]    By using or creating a C-shaped magnet or by placing the north pole of a magnet very close to the south pole of itself or another magnet and ensuring that the magnetic tips are small enough to force the magnetic field to squeeze, large magnetic fields become available in very small spaces. This magnetic field gradient may be used in the oxygen extraction systems  100 ,  200  described above. 
         [0031]      FIG. 3  illustrates a portion of the separator  110  of systems  100 ,  200 . The air that has been liquefied via the compressor  106  is provided to and fed through the interior of an X-shaped tube  300  positioned between four magnet ends  302 - 308 . In one embodiment, magnet ends  302 ,  304  are the respective north and south ends of a single, C-shaped magnet  310  (as shown) while magnet ends  306 ,  308  are the respective north and south ends of a different single, C-shaped magnet  312 . As shown, magnet ends  302 ,  304  are respectively positioned adjacently to adjacent walls  314 ,  316  of tube  300 , and magnet ends  302 ,  304  are respectively positioned adjacently to adjacent walls  318 ,  320  of tube  300 . Alternatively, magnet ends  302 - 308  may be distinct, individual magnets (e.g., magnets  600 ,  602  in  FIG. 6 ) with their north and south poles appropriately positioned as described herein. 
         [0032]      FIG. 4  illustrates an embodiment of separator tube  300  shown in a cross-sectional view. As shown in this embodiment and as discussed above, tube  300  has an “X” shape. The X shape is formed by a portion of each wall  314 - 320  having a respective pair of concave portions  400 ,  402  and a respective pair of convex portions  404 ,  406 . The arms of the X shape are formed by respective pairs of a concave portion  402  and a convex portion  406  of one wall (e.g., wall  318 ) together with respective pairs of a concave portion  400  and a convex portion  404  of an adjacent wall (e.g., wall  316 ). 
         [0033]    Referring again to  FIG. 3 , the magnetic flux lines  322  that occur when placing the magnet ends  302 - 308  adjacently to one other are illustrated. The magnets are positioned within the gaps of the X-shape tube  300  such that the magnetic field is strongest at the limits of the arms of the X (i.e., adjacent to the apex of adjacent convex portions  404 ,  406 ). By pushing the liquid air through the interior  324  of the X-shape tube  300 , the oxygen will naturally be attracted to the highest magnetic field away from the center of the tube  300  while the non-oxygen gases will not be attracted to the limits. Instead, they will be somewhat pushed out due to the higher concentration of oxygen at the extremities. Since the center of the X-shape tube  300  has the lowest gradient of magnetic field, it helps keep the diamagnetic gases in the center of the tube  300 . The preferred gradient of the magnetic field needed to separate oxygen is 10 Tesla/meter, which can be achieved for short range distances with a 1 T magnet as shown. The X-shape is one of many permutations that are possible to create this 10 T/m gradient. The proposed four magnets with opposite poles towards each other can be extended to 2N count of magnetic poles, and the X-shape will be replaced by a tube with 2N arms extended between the magnets. It is also possible to arrange the magnets such that all the magnets have the same poles centered, and this arrangement can be used for even or odd numbers instead of balancing the magnetic poles in the 2N magnets. However, having all the magnets centered would create a constant force pushing the magnets away from each other adding strain to the fixture holding the magnets. Using C-shaped magnets with the opposite poles centralized reduces complexity. 
         [0034]      FIG. 5  illustrates an embodiment of tube  300  of separator  110  shown in an isometric view. As the concentration of oxygen mounts along the flow path of the X-shape tube  300 , apertures or side exit ports  500  in a wall  502  of the X-shape tube  300  extract the pure oxygen out of the tube to a separate channel. Ports  500  may be connected to extraction tubes (shown in  FIG. 6 ) to facilitate extraction of the oxygen. The extracted oxygen can be used in liquid form and stored in oxygen storage tank  112  as shown in  FIG. 1  or expanded to a gas and stored in oxygen storage tank  112  as shown in  FIG. 2 , which allows the system to recoup the compression energy contained in the liquid oxygen as described above. 
         [0035]      FIG. 6  illustrates an isometric view of a portion of the separator  110  of  FIG. 3  according to an embodiment. As shown, magnets  600 - 608  extend along the length of tube  300 . Magnets  600 - 608  correspond to the position of magnet  310 . For simplicity in the drawing, additional magnets that would be paired with magnets  600 - 608  and corresponding to the position of magnet  312  are not shown. However, it is to be understood that such magnets would be present in a physical system. Between magnets  600 - 608 , the side exit ports  400  of tube  300  allow for the oxygen to be extracted. A plurality of extraction tubes  610  fluidly coupled to side exit ports  400  allow for the extracted oxygen to be provided to oxygen storage tank  112  in the case of system  100  or to be provided to expander  202  in the case of system  200 . 
         [0036]    In another embodiment,  FIG. 7  shows another shape of an extraction tube  700  configured to match the process as oxygen is removed from the liquid air passing therethrough. As shown, a first end  702  of tube  700  is X-shaped as described above. Along the length of tube  700  toward a second end  704 , the shape transforms from an X-shape into a circular shape. In one embodiment, the area of the cross-section of second end  704  is less than the area of the cross-section of first end  702 . For example, the area of the cross-section of second end  704  may be 0.8 times the area of the cross-section of first end  702  to take into account the removal of the volume of the oxygen from the liquid air as it travels along tube  700 . Also, side exit ports  706  along tube  700  may diminish as the need to remove oxygen from the liquid air lessens as oxygen is removed along tube travel. 
         [0037]    The included descriptions and figures depict specific implementations to teach those skilled in the art how to make and use the best mode. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these implementations that fall within the scope of the invention. Those skilled in the art will also appreciate that the features described above can be combined in various ways to form multiple implementations. As a result, the invention is not limited to the specific implementations described above, but only by the claims and their equivalents.