Abstract:
A device for separating impurities from gases, such as process gases or hydrogen, includes a filter unit ( 25 ) for separating particulates and fluid media, such as water and/or oil. The filter unit has a coalescing unit ( 29 ) for increasing the drop volume of separated fluid media and a collection unit, preferably in the form of an absorber unit ( 15 ) for binding the separated fluid media.

Description:
FIELD OF THE INVENTION 
     The invention relates to a separation device for separating impurities from gases, such as process gases or hydrogen. 
     BACKGROUND OF THE INVENTION 
     When gases are used as an operating resource, as reagents or the like in technical processes, impurities in the form of particulate and/or fluid media in the process gases in question pose a risk to operational reliability up to and including system failure, may distort analysis results or may result in other malfunctions. In many cases, in addition to particulate impurities, the available gases are also contaminated by fluid media such as water and oil. Among other things, in the case of the increased use of hydrogen (H 2 ) for actuation purposes, such contamination of the gases that serve as operating resources is necessary to anticipate. Freedom from particulate and fluid impurities, such as water and oil, is essential to the operating ability of the relevant, associated systems such as, in particular, fuel cells. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide an improved separation device that allows the separation of such impurities out of process gases, in particular out of hydrogen that is provided for technical purposes. 
     This object is basically achieved according to the invention by a separation device, where the separation device has a filter device for separating out particulate and fluid media such as water and/or oil, a coalescing device to increase the size of the droplets of fluid media that have been separated off, as well as a collecting device, which collecting device is preferably designed in the form of a absorption device that binds the fluid media that have been separated off. 
     According to an advantageous embodiment of the invention, the separation device has at least one separating element, which defines a primary axis, and which can be accommodated in a housing such that the primary axis is oriented at least approximately vertically. The absorption device is disposed in a region of the separating element that allows the transfer of fluid media from the coalescing device to the absorption device through the effect of gravity. A device is thereby created that has a simple design and that allows an independent operation without additional components because the conveyance of fluid media that have been separated off to the absorption device is self-actuating, caused by the effect of gravity. 
     In the case of especially advantageous embodiments, the respective separating element is designed in the manner of a filter cartridge having a support tube. The has media channels and coaxially encompasses the primary axis. The outside of the support tube is enclosed by coalescing device and filter device. That separating element can be implemented in a compact unit, which unit can be replaced in an easy manner at the end of each respective intended operating interval. 
     In an especially advantageous manner, the internal space of the support tube is subdivided into an upper discharge chamber, from which the cleaned gas can be discharged after it has passed through the filter device and the coalescing device, and into a lower absorber chamber that forms the absorption device. 
     For such a separation process, in which the gas that is to be cleaned flows through the separating element from the outside into the inner discharge chamber, in advantageous embodiments, the support tube is enclosed from the outside to the inside by pleated filter material of the filter device and by a part of the drainage layer that forms the coalescing device. In the coalescing device, pre-coagulated filter media that have been separated off by the filter device sink down to the region of the absorber chamber as the droplet size steadily increases. 
     A preferably multi-layered filter mat, made out of fiberous material, for example in the form of a metal fiber nonwoven and causing a pre-coagulation of fluid media, is preferably provided as a filter material. 
     That filter mat that is made of that fiberous material can also form a mesh packet. 
     A metallic mesh or a layer of fiberous material that has been applied according to the spun-spray method may be advantageously provided as a drainage layer. 
     In especially advantageous embodiments, the absorption device contains a mixture of hydrophilic substances and oleophilic substances in the absorber chamber. 
     Such mixture of substances may contain substances, such as silica gel or zeolite beads as hydrophilic components, and substances, such as diatomaceous earth or melt-blown fiberous material as oleophilic components, in the filling of the absorber chamber. 
     In the case of especially advantageous embodiments, the support tube comprises coaxial tube members, which tube members are connected to one another at a connecting piece that separates the discharge chamber from the absorber chamber. Such embodiments are characterized by particular compactness, because the absorber chamber in the lower section of the composite support tube is integrated into the filter cartridge. 
     In the case of such a design having an assembled support tube, the configuration may be advantageously such that a fluid-restraining barrier is provided on the outside of the tube member associated with the discharge chamber, which barrier is formed by a hydrophobic and/or oleophobic fabric, for example. Such barrier may also be formed of any structure having a degree of fineness that allows the passage of gas, but that prevents the passage of drops. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings that form a part of this disclosure: 
         FIG. 1  is a side view in section of a separating element of a separation device according to an exemplary embodiment of the invention; and 
         FIG. 2  is a partial end view in section of the separating element taken along the line II-II of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The separating element  1  depicted in  FIG. 1  can be accommodated in a housing, not shown here, as a component of the separation device according to the invention. For the operation of the separation device, the separating element  1  is disposed in the associated housing such that the primary or longitudinal axis  3  formed by the separating element  1  is oriented at least approximately vertically. When using the separation device in a fueling system having a hydrogen operated drive device, the housing that is to accommodate the separating element  1  is designed for a very high pressure level of 750 to 1000 bar, for example. That housing design is conventional for such applications, and is configured such that the hydrogen (H 2 ) that is to be cleaned flows against the separating element  1  from outside during operation, as is indicated by a flow arrow  5 . The clean gas exits from an discharge chamber  7 , which is located inside the separating element  1 , and moves upward and out. 
     The separating element  1  is designed in the manner of a filter cartridge, having a support tube that comprises two tube members  9  and  11 . Tube members  9 ,  11  are disposed coaxially aligned with the primary axis  3  and with one another, and are connected to one another by a connecting piece  13 . Both tube members  9 ,  11  that form the support tube have media passages in the manner conventional for support tubes, which media passages are not numbered in the drawing. The connecting piece  13  separates the hollow space enclosed by the support tube  9 ,  11  into the upper discharge chamber  7 , located in the upper tube member  9 , and a lower absorber chamber  15 , enclosed by the lower tube member  11 . The absorber chamber  15  is closed at the lower end of the tube member  11  by an end piece  17  in the form of a stopper. A connector  19  is provided at the upper end of the separating element  1  for the discharge of clean gases from the discharge chamber  7 . The connector  19  extends with a connecting piece  21  into the upper end of the tube member  9 . A seal in the form of an O-ring  23  for connecting a line (not shown) is located on connecting piece  23 . 
     A filter device in the form of a cylindrical filter structure  25  of a virtual outer circumference is located on the outside of the separating element  1 . In this case, this filter structure  25  is a water trapping material, which, as shown in  FIG. 2 , is pleated and preferably has a multi-layered design. A filter structure  25  in the form of a metal fiber nonwoven, which causes a pre-coagulation of fluid media, may preferably be provided as a filter material. A mesh packet can be formed that is closed along a longitudinal seam  27 . A drainage layer  29  is connected to the inside of the filter structure  25  as a coalescing device. In this case, the present embodiment is a structure that functions as a coalescer, in which droplets of water and/or oil, which are formed at the filter structure  25  by pre-coagulation, are coagulated into larger drop volumes so that these media drop down by gravity as the droplet size steadily increases. 
     Instead of the pleated filter medium, a preferably multi-layered filter mat may serve as a filter structure, which may be pleated or designed as a cylindrical rolling element. The drainage layer  29  may be a metallic mesh or a layer of fiberous material, which is applied directly to the inside of the pleated filter medium  25 , for example using the spun-spray method. As soon as the droplets that are formed have sunk down into the region of the lower tube member  11  of the support tube, in which the absorber chamber  15  is located, the accumulation of formed droplets reaches the absorber chamber  15  via the fluid passages of the tube member  11 . A mixture of substances comprising hydrophilic substances as well as oleophilic substances is located in the absorber chamber  15  to bind the fluids. In so doing, a mixture of silica gel or zeolite beads may advantageously be provided as hydrophilic components, and substances such as diatomaceous earth or melt-blown fiberous material as oleophilic components. 
     A fluid-retaining barrier may be provided within the drainage layer  29  along the tube member  9  associated with the discharge chamber  7 , for example being formed by a hydrophobic and/or oleophobic fabric. The assembly thus formed is held together at what, in the drawing, is the lower end by the end piece  17 , and at the upper end by the connector  19 . There are edge members  31  or, respectively,  33  located on both of these parts  17  and  19 , which project axially and overlap the facing edge of the filter mat  25 . As shown in  FIG. 1 , these wall parts  31 ,  33  can be pressed inward through the application of compressive force that is applied radially inward, in order to fix the end piece  17  and connector  19  to the narrowing formed on the filter mat  25 . 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.