Abstract:
A fluid transfer coupling is described that includes first and second connectable coupling members that together contain a sealed interior space when connected. A gas or steam purge inlet and a purge outlet are disposed in fluid communication with the sealed interior space for purging potential contaminants out of the interior space. The coupling also includes a vacuum port in fluid communication with the sealed interior space for drawing a vacuum on the sealed interior space and optionally testing the space for an adequate seal. The first coupling member includes a first fluid transfer conduit and the second coupling member includes a second fluid transfer conduit. The first and second fluid transfer conduits are positioned such that they can be connected together within the sealed interior space when the first and second coupling members are connected.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to fluid transfer couplings, and more specifically to fluid transfer couplings for use in environments where the coupling may be exposed to potential contamination of the fluid from the environment. 
         [0002]    Connectable fluid transfer couplings such as quick connect/disconnect couplings are used for a variety of applications such as vehicle refueling or storage tank filling and emptying. For many applications, contamination of the fluid being transferred by materials in the surrounding environment is not a significant concern. In such instances, various types of poppet valves and chucks or other connectors are commonly used, with the principal requirements being ease and reliability of the connection and avoiding leaks of the fluid being transferred into the surrounding environment. 
         [0003]    In some situations, however, contamination of the fluid from contaminants in the surrounding environment can be a significant concern. In some cases, for example, the surrounding environment may contain harsh contaminants such as acids, caustic liquids, organic solvents, or seawater. In some cases, even in the seemingly benign environment of ambient air, contamination of the fluid can be a concern if the fluid is used in a process that is sensitive to oxygen, for example. One example where fluid being transferred through a coupling is at risk of environmental contamination is the underwater transfer of fluids such as cryogenic fluids (e.g., cryogenic oxygen and hydrogen used as oxidant and fuel in a fuel cell) to and from underwater vehicles or stationary powered systems. Ice crystals can form in such environments, and either dissolved materials in the surrounding water or the water itself can undermine performance of sensitive components such as fuel cells. 
         [0004]    In cases where contamination of fluid being transferred through a coupling is a concern, low volume couplings such as so-called ‘zero-volume’ quick connect/disconnects have been proposed. Such couplings typically utilize mating surfaces on connectable coupling members that provide a close surface-to-surface coupling that leaves little void space between the coupling members in which contaminants from the surrounding environment can congregate. However, despite the moniker of ‘zero-volume’, such couplings still leave a small volume in which environmental contaminants can congregate. Some low volume quick connects utilize plungers or similar mechanical components to try and remove any residual contamination. However, even such measures cannot completely remove contaminants from the coupling area, as phenomena such as surface active effects can allow contaminants to cling to the mating surfaces. 
         [0005]    In view of the above and other considerations, there remains a need to develop alternative couplings for fluid transfer. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0006]    According to some aspects of the invention, a fluid transfer coupling includes first and second connectable coupling members that together contain a sealed interior space when connected. A gas or steam purge inlet and a purge outlet are disposed in fluid communication with the sealed interior space for purging potential contaminants out of the interior space. The coupling also includes a vacuum port in fluid communication with the sealed interior space for drawing a vacuum on the sealed interior space. The first coupling member includes a first fluid transfer conduit and the second coupling member includes a second fluid transfer conduit. The first and second fluid transfer conduits are positioned such that they can be connected together within the sealed interior space when the first and second coupling members are connected. 
         [0007]    In some aspects, the coupling includes a gas purge inlet in fluid communication with the sealed interior space. 
         [0008]    In some aspects, the coupling includes a steam purge inlet in fluid communication with the sealed interior space. 
         [0009]    In some aspects, the coupling includes gas and steam purge inlets in fluid communication with the sealed interior space. 
         [0010]    In some aspects, each of the first and second coupling members include separate fluid flow transfer conduits for oxygen and hydrogen, which can be coupled together to form separate oxygen and hydrogen fluid flow transfer conduits when the first and second coupling members are connected. In some aspects each of the first and second coupling members include separate fluid flow transfer conduits for liquid oxygen, gaseous oxygen, liquid hydrogen, and gaseous hydrogen, which can be coupled together to form separate liquid oxygen, gaseous oxygen, liquid hydrogen, and gaseous hydrogen fluid flow transfer conduits when the first and second coupling members are connected. In some aspects, the coupling includes a gas barrier between the oxygen and hydrogen fluid flow transfer conduits within the sealed interior space. This separation can help prevent any unintentional mixing of reactive hydrogen and oxygen within the sealed interior space. 
         [0011]    In some aspects, the coupling includes a purge shroud. When deployed, the purge shroud forms a purge space around the fluid transfer conduits. This purge space is in fluid communication with the purge inlet and the purge outlet and can provide an otherwise sealed area for purging in the interior space of the coupled first and second coupling members. 
         [0012]    In some aspects, the coupling includes a vacuum shroud. When deployed, the vacuum shroud forms a vacuum space around the fluid transfer conduits. This vacuum space is in fluid communication with the vacuum port, and can provide an otherwise sealed area for drawing a vacuum in the interior space of the coupled first and second coupling members. 
         [0013]    In some aspects, the coupling is utilized in a system comprising a polymer electrolyte membrane (PEM) fuel cell, cryogenic oxygen and hydrogen storage tanks, and the fluid transfer coupling is in fluid communication with the cryogenic oxygen and hydrogen storage tanks. 
         [0014]    In some aspects, a method of transferring fluid through a connectable coupling comprises connecting a first coupling member comprising a first fluid transfer conduit to a second coupling member comprising a second fluid transfer conduit. The connected coupling members together form an interior space inside the connected coupling members with the first and second fluid transfer conduits disposed in the interior space. A sealed purge space is formed in the inner space around the fluid transfer conduits, and the purge space is purged with steam or gas. A sealed vacuum space is formed in the inner space around the fluid transfer conduits, and a vacuum is drawn on the sealed vacuum space. After purging and drawing a vacuum, the first and second fluid transfer conduits are connected within the sealed vacuum space and the fluid to be transferred is flowed through the connected fluid transfer conduits. 
         [0015]    In some aspects, the coupling is used, and the method is performed, underwater. 
         [0016]    In some aspects, the purging is performed with steam, and a sealed interior space is cooled after purging to create a partial vacuum 
         [0017]    In some aspects, the coupling comprises separate oxygen and hydrogen fluid transfer conduits having a gas barrier between that forms separate spaces around the oxygen fluid transfer conduits and the hydrogen fluid transfer conduits within the sealed vacuum space. In such aspects, a vacuum can be separately pulled from the space around the oxygen fluid transfer conduits and from the space around the hydrogen fluid transfer conduits. 
         [0018]    In some aspects, the pressure (or vacuum) of the vacuum space(s) can be monitored after the vacuum is drawn. If the vacuum does not meet performance specifications, any or all of the previous steps can be repeated to recover from a poor seal. In some aspects, the purge is repeated. In aspects where separate hydrogen and oxygen spaces are formed within the sealed vacuum space, the vacuum on these spaces can be monitored separately, which can help identify the location of any problems in the ability to maintain the desired vacuum. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying figures, in which: 
           [0020]      FIG. 1A  is a schematic depiction of an exemplary coupling as described herein in its unconnected state; 
           [0021]      FIG. 1B  is a schematic depiction of an exemplary coupling as described herein with coupling members connected; 
           [0022]      FIG. 1C  is a schematic depiction of an exemplary coupling as described herein with coupling members connected and configured for purging; 
           [0023]      FIG. 1D  is a schematic depiction of an exemplary coupling as described herein with coupling members connected and configured for drawing a vacuum; 
           [0024]      FIG. 1E  is a schematic depiction of an exemplary coupling as described herein with coupling members connected and fluid transfer conduits connected; and 
           [0025]      FIG. 2  is a schematic depiction of an exemplary fluid storage system with a coupling as described herein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Referring now to the Figures,  FIGS. 1A-1F  depict an exemplary coupling  10  in various stages of connection. In  FIG. 1A , coupling members  12  and  14  are shown as components on larger structures  16  and  18  such as housings, vehicles, or modules between which fluid is to be transferred. Typically, at least one of the structures  16  or  18  would be a mobile structure such as a vehicle. Alignment bumpers  20  and alignment chuck  22  provide a visual and/or tactile cue for proper alignment of the coupling members  12 ,  14  as they are connected. A retracting cover plate  24  on structure  16  is shown in its retracted position. In  FIG. 1B , the coupling members  12  and  14  are shown in their connected position. 
         [0027]    Coupling member  12  has an articulating arm  23  associated therewith for deployment of various components thereof as further described herein. The deployable components of coupling member  12  include a fluid transfer conduit module comprising a vacuum-jacketed fluid manifold  25 , liquid oxygen conduit  26 , gaseous oxygen conduit  28 , liquid hydrogen conduit  30 , and gaseous hydrogen conduit  32 . Corresponding fluid transfer conduits are disposed in coupling member  14 : liquid oxygen conduit  26 ′, gaseous oxygen conduit  28 ′, liquid hydrogen conduit  30 ′, and gaseous hydrogen conduit  32 ′. 
         [0028]    Turning now to  FIG. 1C , the fluid transfer conduit module has been deployed so that purge shroud  34  engages with purge shroud mating component  36 . Purge seals  38 ,  40  form a seal between the purge shroud  34  and the purge shroud mating component  36  to enclose the sealed purge space  37 . A steam or pressurized gas purge flow is introduced to the sealed purge space  37  through purge nozzles  40  and is discharged through purge drain ports  42 , which can be equipped with one-way check valves to prevent contaminant inflow following purging. Pressurized gas such as nitrogen can be used for purging. Steam such as superheated steam can also be used for purging, and can provide benefits such as melting and removal of any ice particles or buildup from purge space  37 . It can also provide a scrubbing action on surfaces in the sealed purge space  37 , remove precipitates from seawater, and provide a partial vacuum formation during cooling. The pressure of the pressurized gas or steam purge can vary according to environmental parameters, such as the pressure of the environment in which coupling and fluid transfer is to take place. The purge pressure can range from 20 psia to 1000 psia, and more specifically from 300 psia to 700 psia. In some embodiments, the coupling  10  can be equipped with both steam purge and compressed gas purge. Such a configuration can be used, for example, for marine applications involving both underwater and topside fluid transfer connections (e.g., a fuel and oxygen delivery vehicle that takes on fuel and oxygen topside and delivers it to an underwater recipient) where compressed gas purge is used topside and steam purge is used underwater. 
         [0029]    As shown herein, coupling member  12  can be described as an active coupling member whereas coupling member  14  without an articulating arm can be described as a passive coupling member. However, in other embodiments, depending on the particular design features, both of the coupling members can have actively deployable components. For example, the purge shroud  34  could have been deployed from the coupling member  14  (in this embodiment having its own coupling arm, not shown) instead of from the coupling member  12  as shown. 
         [0030]    Turning now to  FIG. 1D , a further deployment imparted by the articulating arm  22  ( FIG. 1A ) of vacuum shroud  42  has been carried out. Vacuum seals  46 ,  48  form a seal to enclose a sealed vacuum space inside of vacuum shroud  42 . A vacuum is drawn on the sealed vacuum space through vacuum jacket flex line  50 , which has fluid transfer conduits disposed within the jacket. After a vacuum has been created in the sealed vacuum space, it can be tested for compliance with specifications. If a sufficient vacuum cannot be achieved or maintained, a process controller (or manual control) can re-initiate any of the previous steps, including docking of the larger structures (e.g., vehicles), connection of the coupling members, sealing of the purge space  37 , purging, and sealing of the vacuum space, followed by re-establishing a vacuum and re-testing. 
         [0031]    In some embodiments, and as shown in  FIGS. 1A-1E , a gas barrier  52  is disposed between the oxygen-containing fluid transfer conduits  26 ,  28 , and the hydrogen-containing fluid transfer conduits  30 ,  32 . The gas barrier  52  seals against gas barrier mating member  54  to provide separate evacuation spaces around the oxygen-containing and hydrogen-containing fluid transfer conduits, which can help avoid any unintentional mixing of any escaped reactive gases as well as help identify any leak sources during vacuum testing. 
         [0032]    After connecting, purging, and establishing a vacuum, the fluid transfer conduits are connected as shown in  FIG. 1E , with the connection of liquid oxygen conduits  26  and  26 ′, gaseous oxygen conduits  28  and  28 ′, liquid hydrogen conduits  30  and  30 ′, and gaseous hydrogen conduits  32  and  32 ′. The conduits can be fitted with self-connecting complementary connectors such as bayonet connectors fitted with poppet valves that are normally closed but are opened by act of connecting the conduits. After connection, fluid flow is initiated through the vacuum-surrounded fluid transfer conduits. The vacuum can be monitored throughout the fluid transfer to assure that there are no leaks. 
         [0033]    Following completion of the fluid transfer, the coupling  10  can be disconnected by essentially reversing the steps described above. After fluid flow is terminated, the conduits  26 ,  28 ,  30 , and  32  are disconnected and retracted from the corresponding conduits,  26 ′,  28 ′,  30 ′, and  32 ′, which causes closure of the poppet valves and sealing of the conduits. Vacuum can be maintained during this stage to protect until baffle  56  is in its resting position to ensure protection of the conduits. Vacuum can then be stopped and the vacuum shroud  44  retracted. Vacuum is then stopped, allowing the surrounding fluid environment (e.g., seawater, air) to flow back into the interior space of the coupling through pressure equalization ports (not shown), which can be equipped with filters. After the interior space has been filled and pressure equalized with the outside environment, the retractable cover  24  can be closed, and the coupling members  12  and  14  can be disconnected. 
         [0034]    The coupling described herein can be used in connection with a wide variety of systems, indeed virtually any system, where a coupling is needed for fluid transfer. In an exemplary embodiment, depicted in schematic fashion in  FIG. 2 , the coupling is utilized in a system for the transfer of cryogenic oxygen and cryogenic hydrogen to a storage system such as for a PEM fuel cell on a vehicle or stationary structure such as an underwater vehicle or stationary structure. As shown in  FIG. 2 , the coupling members  12  and  14  and articulating arm  22  are disposed in oxygen/hydrogen transfer and storage system  60 . In the exemplary embodiment depicted in  FIG. 2 , the structure  16  can be a submerged vehicle or station with an on-board PEM fuel cell stack (not shown) and associated oxygen and hydrogen storage system, and the structure  18  can be a refueling vehicle that replenishes the stored oxygen and hydrogen for the PEM fuel cell stack. In this system, oxygen and hydrogen are delivered from oxygen supply tank  62  and hydrogen supply tank  64  through the coupling members  14  and  12 , into liquid oxygen conduit  26 ″, gaseous oxygen conduit  28 ″, liquid hydrogen conduit  30 ″, and gaseous hydrogen conduit  32 ″ to liquid oxygen storage tank  66 , gaseous oxygen storage tank  68 , liquid hydrogen storage tank  70 , and gaseous hydrogen (and water vapor) storage tank  72 . Liquid oxygen storage tank  66  and liquid hydrogen storage tank  70  are disposed in a cryogenic section  74  of the structure  16 , and other components including the gaseous oxygen storage tank  68  and gaseous hydrogen (and water vapor) storage tank  72  are disposed in a non-cryogenic portion  76  of the structure  16 . Oxygen pump  78  and hydrogen pump  80  assist in transfer of the gaseous portions given off by the liquid oxygen and hydrogen, into the storage tanks  68  and  72 . For purging a sealed interior space in the coupling, pure water from purge storage tank  82  is pumped by pump  84  into steam generator  86 , from where it is directed to the coupling member  12 . A vacuum pump  88  (e.g., a roughing pump plus an ion or electrostatic pump) is utilized to draw a vacuum on the sealed interior space that contains pure water for steam purge. A control system such as an ECU (electronic control unit)  90  is disposed in the non-cryogenic portion  76  for process control and power management. Power can be supplied from an on-board PEM fuel cell stack (not shown) or other sources. 
         [0035]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.