Patent Publication Number: US-2021178314-A1

Title: Air separation modules, nitrogen generation systems, and methods of making air separation modules

Description:
BACKGROUND 
     The present disclosure generally relates to nitrogen generation systems, and more particularly to air separation modules for nitrogen generation systems such as in aircraft. 
     Vehicles, such as aircraft, commonly carry fuel in fuel tanks. The fuel generally resides within the fuel tank as a liquid and bounds an ullage space defined within the fuel tank. The atmosphere within the ullage space typically harbors a mixture of fuel vapor and air from the ambient environments. Since mixtures of fuel vapors and ambient air can be potentially hazardous, e.g., due to combustion in the event of a spark or flame, some vehicles employ inerting systems. Inerting systems limit oxygen concentration within fuel tank ullage spaces by reducing oxygen concentration in the ullage space, generally with an air separation module. 
     Air separation modules separate air received from the ambient environment into an oxygen-enriched air flow and a nitrogen-enriched air flow. The nitrogen-enriched air flow is generally provided to the vehicle fuel tanks by the nitrogen generation system in volume sufficient to limit concentration of oxygen within the fuel tank ullage space to below that sufficient to support combustion. The number of the air separation modules employed by the nitrogen generation system, as well as the size of the associated installation space within the vehicle required for air separation module, generally corresponds to the volume of nitrogen-enriched air required for the vehicle fuel tanks. Vehicles requiring smaller nitrogen-enriched air flows typically employ fewer air separation modules than those requiring larger flows. 
     Such systems and methods have generally been acceptable for their intended purpose. However, there remains a need for improved air separation modules, nitrogen generation systems having air separation modules, and methods of making air separation modules for nitrogen generation systems. 
     BRIEF DESCRIPTION 
     An air separation module is provided. The air separation module includes a separator, a canister, and a nominal-length end cap. The separator is arranged to separate ambient air into an oxygen-enriched air fraction and a nitrogen-enriched air fraction. The canister supports the separator and has a canister end flange, a canister intermediate flange and a canister end, the canister intermediate flange arranged between the canister end flange and the canister end. The nominal-length end cap is fixed to the canister end flange, and the separator extends between the canister end flange and the canister end. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that the separator has a separator length, that the canister has flange spacing distance defined between the canister end flange and the canister intermediate flange, and that the separator length is greater than the flange spacing distance. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include an extended-length end cap, that the extended-length end cap is longer than the nominal-length end cap, and that the canister intermediate flange couples the extended-length end cap to the canister. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include a flow control valve supported by the extended-length end cap, that the extended-length end cap fluidly couples the flow control valve with the separator to communicate a compressed air flow to the separator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that the extended-length end cap has an extended-length end cap mounting feature for fixation of the air separation module within an aircraft, and that the extended-length end cap mounting feature is adjacent to the canister intermediate flange. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that the extended-length end cap has an extended-length end cap flange, and that the extended-length end cap flange is fastened to the canister intermediate flange. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that a portion of the canister between the canister end and the canister intermediate flange spaces the separator from the extended-length end cap. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that a terminal portion of the separator is arranged within the extended-length end cap. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that the nominal-length end cap has a nominal-length end cap flange and that the nominal-length end cap flange couples the nominal-length end cap to the canister end flange. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that the separator terminates at the canister end flange and that the nominal-length end cap has no mounting feature for fixation of the air separation module within an aircraft. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that the canister has a diameter that is about nine (9) inches (about 23 centimeters). 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include a filter module supported by the nominal-length end cap and that the nominal-length end cap fluidly couples the separator to the filter module for filtering the nitrogen-enriched air fraction from the separator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the air separation module may include that the canister defines a discharge port for discharging an oxygen-enriched received from the separator. 
     A nitrogen generation system is also provided. The nitrogen generation system includes an air separation module as described above; an extended-length end cap, the canister intermediate flange coupling the extended-length end cap to the canister intermediate flange; and a flow control valve supported by the extended-length end cap, and that the extended-length end cap fluidly couples the flow control valve with the separator to issue a nitrogen-enriched air flow from the canister. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the nitrogen generation system may include that the canister defines an overboard air discharge port for discharging an oxygen-enriched received from the separator, and that the nitrogen generation system further includes a filter module supported by the nominal-length end cap, the nominal-length end cap fluidly coupling the filter module to the separator for communicating compressed air the separator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the nitrogen generation system may include that a terminal portion of the separator is arranged within the extended-length end cap, that the extended-length end cap has an extended-length end cap flange, and that the extended-length end cap flange is fastened to the canister intermediate flange. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the nitrogen generation system may include that a portion of the canister between the canister end and the canister intermediate flange spaces the separator from the extended-length end cap, that the extended-length end cap has an extended-length end cap mounting feature for fixation of the air separation module within an aircraft, and that the extended-length end cap mounting feature is adjacent to the canister intermediate flange. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the nitrogen generation system may include a fuel tank carried by an aircraft and that the fuel tank is fluidly coupled to the separator through the flow control valve. 
     A method of making an air separation module is additionally provided. The method includes defining a canister having a canister end flange, a canister intermediate flange and a canister end, the canister intermediate flange arranged between the canister end flange and the canister end; supporting a separator configured to separate ambient air into an oxygen-enriched air fraction and a nitrogen-enriched air fraction within the canister such that the separator extends between the canister end flange to the canister end; and fixing a nominal-length end cap to the canister end flange. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the nitrogen generation system may include fixing an extended-length end cap to the canister intermediate flange; supporting a flow control valve with the extended-length end cap; fluidly coupling the flow control valve with the separator to issue a nitrogen-enriched air flow from the canister; supporting a filter module with the nominal-length end cap; and fluidly coupling the filter module to separator to provide a compressed air flow to the separator. 
     Technical effects of the present disclosure include relatively large inerting capability in relation to space occupied by the air separation module. In certain examples air separation modules described herein have canisters separators of length greater than the spacing distance between the air separation module end caps, providing larger canister volume than that defined within the canister between the air separation module ends caps. In accordance with certain examples air separation modules described herein include separators partially contained within at least one of the end caps, providing larger canister volume than that defined between within the canister between the air separation module end caps. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is a schematic view of an air separation module constructed in accordance with the present disclosure, showing a nitrogen generation system carried by an aircraft and including the air separation module providing a nitrogen-enriched air flow to a fuel tank; 
         FIG. 2  is a perspective view of the air separation module of  FIG. 1  according to an example, showing an end cap housing a portion of the air separation module canister and separator; 
         FIG. 3  is a cross-sectional view of the air separation module of  FIG. 1  according to the example, showing the canister and separator extending beyond a canister intermediate flange connecting the end cap to the canister; and 
         FIG. 4  is a block diagram of a method of making an air separation module, showing operations of the method according to an illustrative and non-limiting example of the method. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an example of an air separation module constructed in accordance with the disclosure is shown in  FIG. 1  and is designated generally by reference character  100 . Other embodiments of air separation modules, nitrogen generation systems having air separation modules, and methods of making air separation modules for nitrogen generation systems, are provided in  FIGS. 2-4 , as will be described. The systems and methods described herein can be used for generating nitrogen-enriched air flows for inerting fuel tanks, such as fuel tanks carried by aircraft, though the present disclosure is not limited to fuel tanks or to aircraft in general. 
     Referring to  FIG. 1 , a vehicle  10 , e.g., an aircraft is shown. The vehicle  10  includes a fuel system  12 , a compressed air source  14 , and a nitrogen generation system  102 . The fuel system  12  includes a fuel tank  16  containing liquid fuel  18 . The liquid fuel  18  and the fuel tank  16  define between one another an ullage space  20 . The ullage space  20  is in fluid communication with the nitrogen generation system  102  and contains therein a mixture of fuel vapors  22  and a nitrogen-enriched air faction  24  provided by the nitrogen generation system  102 . It is contemplated that that the nitrogen-enriched air fraction be sufficient to retain concentration of oxygen within the ullage space  20  to limit (or eliminate entirely) probability of fuel vapor combustion in the event that an ignition source comes into communication with the fuel vapors  22 . In certain examples the compressed air source  14  can be a compressor section of a gas turbine engine. 
     The nitrogen generation system  102  includes a source conduit  104 , a supply conduit  106 , and the air separation module  100 . The source conduit  104  fluidly connects the compressed air source  14  to the air separation module  100 . The supply conduit fluid connects the air separation module  100  to the fuel system  12 , e.g., to the fuel tank  16 . The compressed air source  14  is configured to provide a compressed air flow  26 , e.g., a bleed air flow from a gas turbine engine, from the ambient environment  28 . The air separation module  100  is configured to separate the compressed air flow  26  into the nitrogen-enriched air fraction  24 , which the air separation module  100  provides to the supply conduit  106 , and an oxygen-enriched air faction  30 , which the air separation module  100  returns to the ambient environment  28  via a discharge port  108  (shown in  FIG. 2 ). The supply conduit  106  provides the nitrogen-enriched air fraction  24  to the fuel system  12 , e.g., to inert the ullage space  20  within the fuel tank  16 . 
     With reference to  FIG. 2 , the air separation module  100  is shown. The air separation module  100  includes a canister  110 , a nominal-length end cap  112 , and an extended-length end cap  114 . The air separation module  100  also includes a flow control valve  116 , a filter module  118 , and an oxygen-enriched air fraction duct  120 . 
     The canister  110  has a canister end flange  122 , a canister intermediate flange  124 , and a canister end  126  (shown in  FIG. 2 ). The canister  110  also has a thickened portion  128 , one or more canister mounting feature  132 , and defines the discharge port  108 . The canister end  126  is arranged within the extended-length end cap  114 , is arranged on an end of the canister  110  opposite the canister end flange  122  and is configured to couple the extended-length end cap  114  to the extended-length end cap  114  to the canister  110 . The canister end flange  122  is arranged on an end of the canister  110  opposite the extended-length end cap  114  and is configured to couple the nominal-length end cap  112  to the canister  110 . In certain examples the canister  110  has a diameter  168  (shown in  FIG. 3 ) that is about nine (9) inches (about 23 centimeters), which allows the air separation module  100  to serve as a drop-in replacement for a legacy air separation module having smaller nitrogen-enriched air flow generating capability. 
     The canister intermediate flange  124  is arranged between the canister end  126  and the canister end flange  122 . The thickened portion  128  of the canister  110  is arranged to provide longitudinal stiffness to the canister  110  and, in the illustrated example, couples the one or more canister mounting feature  132  to the canister  110 . The one or more canister mounting feature  132  are arranged for fixation of the air separation module  100  to a vehicle, e.g., the vehicle  10  (shown in  FIG. 1 ). In the illustrated example the one or more canister mounting feature  132  is arranged to seat therein a tie-rod, which allows the air separation module  100  to be fixed within certain legacy nitrogen generation systems. 
     The nominal-length end cap  112  has a nominal-length end cap flange  134 , a filter support  136  and defines an inlet port  138 . The filter support  136  is arranged on a side of the nominal-length end cap  112  opposite the nominal-length end cap flange  134 . The nominal-length end cap flange  134  extends about the nominal-length end cap  112 , has a fastener pattern  150  and receives therethrough a plurality of fasteners  140 . The plurality of fasteners  140  fix the nominal-length end cap  112  against the canister end flange  122 , the nominal-length end cap  112  thereby connected to the canister  110 . The filter support  136  is configured to seat thereon a filter module  118 . The inlet port  138  extends through the nominal-length end cap  112  and fluidly connects the canister  110  to the filter module  118 , and therethrough with the source conduit  104 . 
     The extended-length end cap  114  is similar to the nominal-length end cap  112  and additionally includes an extended-length end cap flange  142 , a flow control valve support  144 , and an extended-length end cap mounting feature  146 . The flows control valve support  144  is configured to seat thereon the flow control valve  116  and is arranged with extended-length end cap flange  142  on a common end of the extended-length end cap  114 . The extended-length end cap flange  142  extends about the extended-length end cap  114 , has a fastener pattern  148 , and receives therethrough a plurality of fasteners  152 . The plurality of fasteners  152  fix the extended-length end cap  114  against the canister intermediate flange  124 , the extended-length end cap  114  thereby connected to the canister  110 . The extended-length end cap mounting feature  146  is configured to fix the air separation module  100  in the vehicle  10  (shown in  FIG. 1 ), e.g., by seating therein a tie rod or airframe structure. An outlet port  154  (shown in  FIG. 3 ) extends through the extended-length end cap  114  and fluidly connects with the flow control valve  116 , and therethrough with the supply conduit  106  to provide the nitrogen-enriched air fraction  24  (shown in  FIG. 1 ) to the fuel tank  16  (shown in  FIG. 1 ). 
     With reference to  FIG. 3 , the air separation module  100  is shown. The air separation module  100  generally includes a separator  156  configured to separate ambient air, e.g., the compressed air flow  26  (shown in  FIG. 1 ), into an oxygen-enriched air fraction, e.g., the oxygen-enriched air fraction  30  (shown in  FIG. 1 ), and a nitrogen-enriched air fraction, the nitrogen-enriched air fraction  24 . The canister  110  supports the separator  156  and has the canister end flange  122 , the canister intermediate flange  124  and the canister end  126 . The canister intermediate flange  124  is arranged between the canister end flange  122  and the canister end  126 . The nominal-length end cap  112  is fixed to canister end flange  122  and the separator  156  extends between the canister end flange  122  and the canister end  126 . 
     It is contemplated that air separation module  100  be extended, e.g., be of length greater than that of certain legacy air separation modules. In this respect, in certain embodiments, the separator  156  has a separator length  158 , the canister has a flange spacing distance  160  defined between the canister end flange  122  and the canister intermediate flange  124 , and the separator length  158  is greater than the flange spacing distance  160 . In accordance with certain embodiments, the extended-length end cap  114  has an extended end cap portion  162  extending from the extended-length end cap flange  142  in a direction opposite the nominal-length end cap  112 , and a separator terminal portion  164  is contained within the extended end cap portion  162  of the extended-length end cap  114 . It is also contemplated that a canister extended portion  166  of the canister  110 , arranged between the canister end  126  and the canister intermediate flange  124 , space the extended-length end cap  114  from the separator  156 . This allows the canister  110  to support the separator terminal portion  164  prior to and during assembly of the extended-length end cap  114  on the canister  110 . 
     In the illustrated example the nominal-length end cap  112  is coupled to the canister  110  by the nominal-length end cap flange  134 . In this respect the nominal-length end cap flange  134  is fixed to the canister end flange  130  by the plurality of fasteners  152 , which are seated in the fastener pattern  150 . Fixation of the nominal-length end cap  112  to the canister  110  with the nominal-length end cap flange  134  and the canister end flange  130  provides stiffness to the air separation module  100 . In certain examples the stiffness allows the filter module  118  to be supported by the nominal-length end cap  112  such that the nominal-length end cap  112  fluidly couples the separator  156  to the filter module  118  for filtering the nitrogen-enriched air fraction  24  (shown in  FIG. 1 ) issued from the canister  110 . In accordance with certain example the separator  156  terminates at the canister end flange  122  and no mounting feature for fixation of the air separation module  100  within the vehicle  10 , e.g., an aircraft, allowing the air separation module  100  to extend from an installation envelope of a legacy air separation module and occupy additional space adjacent the to the installation envelope. 
     In the illustrated example the extended-length end cap  114  is longer than the nominal-length end cap  112  and is coupled to the canister  110  by the canister intermediate flange  124 . In certain examples the extended-length end cap flange  142  couples the extended-length end cap  114  to the canister intermediate flange  124 , e.g., via a plurality of fasteners  152  (shown in  FIG. 1 ) received within the fastener pattern  150  (shown in  FIG. 1 ). The canister intermediate flange  124  to the extended-length end cap flange  142  provides stiffness to the air separation module  100 , allowing the separator  156  and the canister extended portion  166  to extend into the extended-length end cap  114 . In certain examples the flow control valve  148  is supported by the extended-length end cap  114  and the extended-length end cap  114  fluidly couples the flow control valve  148  with the separator  156  to communicate a compressed air flow  26  (shown in  FIG. 1 ) to the separator  154 . In accordance with certain embodiments, the second end mounting feature of the extended-length end cap  114  can be adjacent to the canister intermediate flange  124  for fixation of the air separation module  100  within the vehicle  10  (shown in  FIG. 1 ). 
     With reference to  FIG. 4 , a method  200  of making air separation module, e.g., the air separation module  100 , is shown. The method  200  includes defining a canister having a canister end flange, a canister intermediate flange, and a canister end, the canister intermediate flange arranged between the canister end flange and the canister end; e.g., the canister  110  (shown in  FIG. 2 ) having the canister end  126  (shown in  FIG. 2 ), the canister intermediate flange  124  (shown in  FIG. 2 ), and the canister end flange  130  (shown in  FIG. 2 ); as shown with box  210 . The method  200  also includes supporting a separator configured to separate a compressed air flow into an oxygen-enriched air fraction and a nitrogen-enriched air fraction, e.g., the separator  156  (shown in  FIG. 3 ), within the canister such that the separator extends between the canister end flange to the canister end, as shown with box  220 . The method  200  additionally includes fixing a nominal-length end cap, e.g., the nominal-length end cap  112  (shown in  FIG. 2 ), to the canister end flange, as shown box  230 . 
     As shown with box  240 , it is contemplated that the method  200  additionally includes fixing an extended-length end cap, e.g., the extended-length end cap  114  (shown in  FIG. 2 ) to the canister intermediate flange. In certain examples the method includes supporting a flow control valve, e.g., the flow control valve  116  (shown in  FIG. 2 ), from the extended-length end cap such that the separator is fluidly coupled to the flow control valve to issue the nitrogen-enriched air flow fraction from the canister, as shown with boxes  250  and  260 . In accordance with certain examples the method  200  includes supporting a filter module, e.g., the filter module  118  (shown in  FIG. 2 ), with the nominal-length end cap and fluidly coupling the separator to the filter module for filtering the compressed air flow communicated to the separator, e.g., the compressed air flow  26  (shown in  FIG. 1 ), as shown with boxes  270  and  280 . 
     Fuel tanks, such as fuel tanks used to store liquid fuel in vehicles like aircraft, commonly contain fuel vapors within the ullage space of the fuel tank. Because such fuel vapors can present a fire hazard some vehicles include nitrogen generation systems with air separation modules. The air separation modules are typically arranged to provide a flow of nitrogen-enriched air to the fuel tank ullage space, limiting concentration of oxygen within the fuel tank ullage space and reducing (or eliminating entirely) the fire hazard potentially posed by the fuel vapors. The volume of nitrogen enriched air is generally constrained by the size of the air separation module and space allocated to the air separation module within the vehicle. 
     In examples provided herein air separation modules are provided with extended separators to provide relatively large nitrogen-enriched air flow generation capacity. In certain examples the diameter and/or placement of the fixation features of the air separation module corresponds an installation envelope of a legacy air separation module. In accordance with certain examples air separation modules include an extended-length end cap. The extended-length end cap provides increased canister volume, portions of the canister length and the separator arranged within the extended-length end cap to provide additional nitrogen-enriched air flow generation capacity, the air separation module thereby providing increased inerting capability within a predetermined, e.g., legacy, air separation module installation envelop. 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.