Abstract:
A gas and liquid phase separator apparatus and an apparatus for energy production based on fuel cells within the phase separator.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a gas and liquid phase separator as well as to an assembly for energy production based on fuel cells, which is provided with such a phase separator. 
     2. Related Art 
     Gas and liquid phase separators are used in many industrial applications, especially in the field of energy production based on fuel cells. 
     Conventionally, an assembly for energy production based on fuel cells comprises a cell block, which has an anode compartment in which the oxidation of hydrogen takes place, as well as a cathode compartment in which the oxygen in air is reduced, with water being produced. 
     It is in this case known to provide a gas separator downstream of the cathode compartment, making it possible to separate the oxygen-depleted air and the water which are discharged from this cathode compartment. It is also possible to provide another phase separator in the outlet line of the anode compartment, which carries a mixture of hydrogen and water. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a phase separator which is advantageous in terms of compactness and which can be used, in particular but not exclusively, in an assembly for energy production based on fuel cells. 
     To this end it relates to a gas and liquid phase separator comprising a body, an inlet for a diphasic mixture containing gas and liquid to be separated, a gas outlet and a liquid outlet, characterized in that it furthermore comprises a hydrophilic structure which is arranged in the body and delimits an internal space and an external space with respect to this body, in that means are provided for creating vortices in the diphasic mixture when it is flowing through said internal space, so as to recover the liquid against the walls of said hydrophilic structure, in that the gas outlet is in communication with the internal space, and in that the liquid outlet is in communication with the external space. 
     According to other characteristics of the invention:
         the means for producing vortices comprise a profiled auxiliary member, in particular an impeller;   the means for producing vortices consist of said hydrophilic structure.       

     The invention also relates to an assembly for energy production based on fuel cells, comprising a fuel cell block which has a cathode compartment, an anode compartment, at least two gas feed circuits and at least two discharge circuits, each of which makes it possible to discharge a mixture of gas and water from the cell block, this assembly being characterized in that at least one discharge circuit leads into a gas and liquid phase separator as defined above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be understood more clearly on reading the following description, which is given solely by way of nonlimiting example and refers to the appended drawings, in which: 
         FIG. 1  is a schematic view illustrating an assembly for energy production based on fuel cells, which is equipped with a phase separator according to the invention; 
         FIG. 2  is a view in diametral section illustrating this phase separator more precisely; 
         FIG. 3  is a view in section similar to  FIG. 2 , illustrating a phase separator according to a first alternative embodiment of the invention; 
         FIG. 4  is a view in section on the line IV—IV in  FIG. 3 ; 
         FIG. 5  is a view in section similar to  FIGS. 1 and 2 , illustrating a phase separator according to another alternative embodiment of the invention; and 
         FIG. 6  is a view in section on the line VI—VI in  FIG. 4 . 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The energy production assembly schematically represented in  FIG. 1  comprises a fuel cell block, which has a cathode  2  as well as an anode (not shown). 
     This cathode compartment  2  receives an air feed circuit  6  at an inlet  4 . A circuit  8  furthermore makes it possible to discharge a mixture of oxygen-depleted air and water from the outlet  10  of this cathode. 
     The discharge circuit  8  leads into a separator  12 , making it possible to separate the gas and liquid phases of the aforementioned mixture. A line  14  makes it possible to recycle the water separated from this mixture back to the inlet of the cathode  2 . The separated gas phase, essentially consisting of oxygen-depleted air, is furthermore discharged via a line  16 . 
     The fuel cell block is also equipped with two additional circuits (not shown), respectively for supplying the anode with hydrogen and for discharging the depleted hydrogen mixed with water from this anode. This discharge circuit may also lead into another phase separator (not shown) similar to the one  12 . 
     Referring now to  FIG. 2 , the phase separator  12  comprises an inlet  18  placed in communication with the discharge circuit  8 . This tubular inlet  18  extends into a cylindrical body  20 , which is coaxial with this inlet but has a larger diameter. 
     The body  20  ends in an outlet  22 , which is coaxial with the inlet  18  and has a similar diameter. This body contains a hydrophilic membrane  24 , which is arranged so as to form a cylinder coaxial with the inlet  18  and the outlet  22 , and with the same diameter as them. The membrane  24 , for example made of polyethylene or nylon, is to this end held in place by seals and clamping. 
     This membrane hence defines two spaces in the body of the separator, respectively an internal space  26  and an external space  28 . 
     The external space  28 , which is annular, is placed in communication with a radial outlet  30  with which the body  20  is provided. This outlet  30 , which makes it possible to discharge the water, as will be explained below, leads into the recycling line  14 . 
     A coalescer pad  32  of the known type is arranged in the inlet  18  of the separator  12 . It makes it possible to increase the size of the water droplets to be recovered, so as to improve their separation. 
     Downstream of this pad  32 , in the example which is represented, an impeller  34  is provided which is arranged immediately upstream of the hydrophilic membrane  24 . This impeller makes it possible to create vortices in the flow of gas and water taken in through the inlet  18 . 
     The mixture hence follows along an approximately helicoid path in the internal space  26 , which is indicated by the arrows F. As a variant, such vortices may also be induced by replacing the impeller  34  with a tangential gas inlet. 
     In this way, because of the centrifugal force, the water initially present in the mixture becomes pressed against the internal walls of the membrane  24 , which hence carries out the recovery of this water. 
     It is discharged by means of the radial outlet  30 . The quality of this discharge may be improved by keeping the pressure in the external space  28  at a value lower than that prevailing in the internal space  26 . 
     To this end, suction may be applied to the water at the outlet  30 , for example by pumping. As a variant, it is also possible to utilize the pressure difference naturally existing between these internal and external spaces,  26  and  28  respectively. 
     The membrane  24  is such that its bubble point is higher than the pressure difference existing between the internal space  26  and the annular external space  28  during operation. This makes it possible to avoid any passage of gas toward this external space  28 , so that only the water is present therein. 
       FIGS. 3 and 4  illustrate a first alternative embodiment of the invention. In these figures, the mechanical elements which are identical to those in  FIG. 2  are assigned the same reference numbers, to which 50 has been added. 
     The separator  62  in these  FIGS. 3 and 4  differs from the one  12  in  FIG. 2  firstly in that the membrane  74  does not have a cylindrical profile. 
     Specifically, as shown by  FIG. 4 , this membrane  74  is involute, or folded, as viewed in a section transverse to the flow of the mixture. This makes it possible to increase the contact area of this membrane, and therefore to improve the separation. 
     Furthermore, an additional membrane  86  is arranged in the internal space  76  delimited by the primary membrane  74 . This membrane  86  therefore separates this internal space  76  into a central region  88  and an intermediate region  90 , which is annular. 
     The bubble point of the secondary membrane  86  is advantageously higher than the pressure difference existing between the central region  88  and the intermediate region  90 . It should be noted that this pressure difference ensures substantially integral recovery of the water initially present in the central region  88 . This hence avoids stagnation of this water in this region  88 , and guarantees efficient separation. 
     A purge (not shown) may be provided on the walls of the body  70 , so as to feed into the intermediate region  90 . Such a purge makes it possible to discharge the air present in this intermediate region  90 , and therefore to prevent this air from remaining trapped and blocking the separator. 
     The primary membrane  74 , the bubble point of which is higher than that of the secondary membrane  86 , lastly ensures recovery of all the water taken in through the inlet  68 . This water is subsequently discharged through the outlet  80 , in a manner similar to that which was described with reference to  FIG. 2 . 
     It should be noted that, in the exemplary embodiment of the  FIGS. 3 and 4 , the pressure prevailing in the central region  88  is slightly higher than that of the intermediate region  90 , which is itself much higher than that prevailing in the external space  78 . 
       FIGS. 5 and 6  illustrate another alternative embodiment. In these figures, the mechanical elements which are similar to those in  FIG. 2  are assigned the same reference numbers, to which 100 has been added. 
     The separator  112  in  FIGS. 5 and 6  differs from the one in  FIGS. 2 to 4  in that it does not have an impeller. Specifically, the turbulent movement of the flow of water and gas taken in through the inlet  118  is ensured by the actual configuration of the hydrophilic membrane  124 . 
     Here, the latter has a folded or multilobed, or involute shape, as viewed in a section transverse to the flow direction of the mixture of water and gas. It should be noted that the shape of the folds of the membrane is such that they leave a central free section  125  remaining, the transverse dimension of which is particularly small. 
     Furthermore, as viewed from the side in  FIG. 5 , the membrane  124  also has a spiral arrangement, i.e. its forms a helix overall. In this way, the mixture of water and air taken in through the inlet  118  flows along a vortex as it progresses along the membrane  124 . 
     The embodiment of these  FIGS. 5 and 6  is more particularly advantageous in economic terms. This is because it makes it possible to combine two separate functions in a single membrane, namely those of creating vortices as well as recovering the water. 
     The invention makes it possible to achieve the objects mentioned above. 
     This is because the phase separator according to the invention has a simple structure, and employs a small number of constituent elements. 
     Furthermore, the use of a hydrophilic membrane makes it possible to divide this separator into two separate compartments, which are respectively intended for discharging the water and the gas. In this way, the compartment reserved for the water can be provided with a lower pressure, which guarantees particularly efficient recovery thereof. 
     It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.