Abstract:
A apparatus for substantially dehumidifying an insulating annular space ( 108 ) is provided. This apparatus includes an insulated surrounding envelope ( 106 ), an inner cylindrical device ( 107 ) and a partial annular cylinder ( 100 ) comprising at least two porous zones. This apparatus positions the partial annular cylinder ( 100 ) within the insulating annular space ( 108 ) that is formed by the inner cylindrical device ( 107 ) positioned within the insulated surrounding envelope ( 106 ). This partial annular cylinder ( 100 ) holds adsorbent.

Description:
This application is a §371 of International PCT Application PCT/EP2008/062850, filed Sep. 25, 2008. 
     BACKGROUND 
     There are many devices or assemblies that incorporate an insulating region. Often, within this insulating region is an active element, whose purpose is to reduce or remove moisture from this region. If this insulating region is maintained in an evacuated state, it is important to reduce or remove moisture in order to avoid problems with vacuum pumping. There is a need within the industry for a moisture removal device that ensures the desiccation of the vacuum insulating region. 
     The process in the present application is directed to a moisture removal device that satisfies the need in society in general for a moisture removal device that ensures the desiccation of the vacuum insulating region. 
     U.S. Pat. No. 3,108,706 discloses a system wherein a partial vacuum insulating space is created within an annular area. The problem that this patent addresses is the release into the vacuum of hydrogen by the metal itself. An adsorption agent is introduced into this insulating space that is specifically selective to adsorb hydrogen. 
     UK 2,139,311 discloses a system that also addresses the release of hydrogen into the vacuum by the metal itself. An adsorption device is either spirally wound around one of the surfaces, or the adsorption material is formed into a sintered body and inserted into this space. Either system is designed to be heated externally to regenerate the adsorbent. This system requires special manufacturing, construction and operating procedures as well as specialized adsorbent, which can not be easily replaced at the end of its useful life. It is not easily retrofitted into existing systems. 
     U.S. Pat. No. 4,704,068 discloses a system wherein a partial vacuum insulating space is created within an annular area. An adsorption agent is sealed in a gas-and-moisture tight container, introduced into this insulating space, and ruptures upon the final evacuation of the partial vacuum insulating space. This system requires special manufacturing, and operating procedures, which must be repeated every time the adsorbent reaches the end of its useful life. It also may not be easily retrofitted into all existing systems. 
     U.S. Pat. No. 6,087,581 discloses a system wherein a partial vacuum insulating space is created within an annular area, and wherein an adsorbent is placed in physical and thermal contact with the outer containment wall, such that the thermally regenerable adsorbent may be heated through the outer containment wall to regenerate the adsorbent. This system requires special manufacturing, construction and operating procedures as well as specialized adsorbent, which can not be easily replaced at the end of its useful life. It is not easily retrofitted into existing systems. 
     SUMMARY OF THE INVENTION 
     The goal of the present invention is to improve upon previously known systems. The instant invention is essentially characterized as an apparatus for substantially dehumidifying an insulating annular space comprising:
         an insulated surrounding envelope,   an inner cylindrical device,   a partial annular cylinder comprising at least two porous zones,   wherein said partial annular cylinder is positioned within an insulating annular space formed by said inner cylindrical device positioned within said insulated surrounding envelope, and   wherein said partial annular cylinder holds absorbent.       

     Such an apparatus solves the problem of need for a moisture removal device that ensures the desiccation of the vacuum insulating region. Such an apparatus allows for easy retrofitting into existing systems, requires no specialized manufacturing or operating procedures, and allows for easy removal and replacement when the adsorbent has reached the end of its useful life. Such a system would allow the external regeneration of the adsorbent if necessary, and would not require any in situ heating to regenerate the adsorbent. 
     Moreover, other embodiments may comprise one or more of the following features. 
     Said inner cylindrical device may be concentrically positioned within said insulated surrounding envelope. Said partial annular cylinder may have a radial axis defined by the annular cross section, and two longitudinal cross sections that are defined by the longitudinal axis, wherein said longitudinal axis is normal to said radial axis. 
     Said annular cross section may be further defined by an inner radius and an outer radius. Said longitudinal cross sections may be further defined by an inner edge, an outer edge, a distal edge and a proximal edge. 
     Said truncated annular cross section may comprise a semicircle. Said truncated annular cross section may comprise a major arc. Said major arc may have an inscribed angle of between 180 degrees and 270 degrees. Said major arc may have an inscribed angle of between 200 degrees and 250 degrees. Said major arc may have an inscribed angle of between 200 degrees and 230 degrees. 
     Any gas or vapor present within said annular space may contact said absorbent. Said gas or vapor may comprise air. Said inner cylindrical device may comprise a single distillation column. Said insulating annular space may be substantially evacuated. Said at least two porous zones may be located at said longitudinal cross sections. Said porous zones may comprise a permeable mesh barrier. 
     Said permeable mesh barrier may be secured to said partial annular cylinder by means of a plurality of fasteners positioned along the perimeter of said porous zone. Said fasteners may be selected from the group consisting of rivets, bolts, and screws. 
     Said partial annular cylinder may have an internal volume of 0.03 cubic meters, preferably 0.04 cubic meters. Said partial annular cylinder may have an internal volume of 0.04 cubic meters, preferably 0.05 cubic meters. Said partial annular cylinder may have an internal volume of 0.06 cubic meters, preferably 0.07 cubic meters 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, and in which: 
         FIG. 1   a  is a schematic front view of one embodiment of the current invention. 
         FIG. 1   b  is a schematic top view of an embodiment of the current invention. 
         FIG. 1   c  is a schematic detail of the end of an embodiment of the current invention. 
         FIG. 2   a  is a schematic top view of an embodiment of the current invention. 
         FIG. 2   b  is a schematic front view of an embodiment of the current invention. 
         FIG. 3  is an isometric illustration of an embodiment of the current invention. 
         FIG. 4  is a front view of an embodiment of the current invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For a further understanding of the nature and objects for the present invention, reference should be made to the detailed description, taken in conjunction with the accompanying drawing, in which like elements are given the same or analogous reference numbers and wherein: 
     Illustrative embodiments are described below. While the process in the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. 
     The following examples and embodiments are directed toward, but not limited to, a single column distillation apparatus of an air separation unit. 
     As used herein, the term “substantially dehumidify” is defined as removing sufficient moisture from any atmosphere that may be present, as to result in a relative humidity of less than 5%, preferably less than 1%, even more preferably less than 0.1%. 
     As used herein, the term “substantially evacuated” is defined as having sufficient atmosphere removed to result in a pressure of less than 10 Pa, preferably less than 1 Pa, even more preferably less than 0.1 Pa. 
     Now turning to  FIGS. 1   a ,  1   b , and  1   c , an adsorption box  100  in accordance with embodiments of the present invention is illustrated. The adsorption box  100  comprises porous zones  101 , fasteners  102 ,  104 , frame  105 , and permeable mesh barriers  103 . 
     As indicated in  FIG. 1   a , porous zone  101  comprises an opening in the end of adsorption box  100  that is covered by a permeable mesh barrier  103 . This permeable mesh barrier  103  allows gases and vapors to pass through, while containing adsorbent within the adsorption box  100 . This adsorbent may be silica gel or activated alumina. Permeable mesh barrier  103  is attached to adsorption box  103  by means of frame  105 , which is rigidly secured to adsorption box  100  by means of fasteners  102  and  104 . 
     Permeable mesh barriers  103  may be comprised of any suitable material known to the skilled artisan. Permeable mesh barriers  103  may be fabricated as part of frame  105 , thus facilitating the secure attachment to the body of adsorption box  100  with fasteners  102 ,  104 . 
       FIG. 1   b  is a schematic top view of one embodiment of the present invention, illustrating the radial cross section of the truncated annular cylindrical shape of one embodiment of adsorption box  100 . This view illustrates filler portal  109 , which is used to load adsorbent  110  into adsorption box  100 . From this view, longitudinal cross sections  111  are illustrated as the faces of the truncated annular cylinder. Porous zones  101  are located at these longitudinal cross sections  111 . 
       FIG. 1   c  is a schematic view of one embodiment of the present invention, illustrating a detailed view of porous zone  101  as illustrated in  FIG. 1   b . From this view, one embodiment of the attachment of permeable barrier  103  to the body of adsorption box  100  may be seen. With permeable mesh barrier  103  positioned between the body of adsorption box  100  and frame  105 , fasteners  102  and  104  (not shown for clarity) are used to secure the frame and permeable barrier to the body of adsorption box  100 . 
     As indicated in  FIGS. 2   a  and  2   b , adsorption box  100  comprises a hollow annular cylinder, with an annular radial cross-section.  FIG. 2   a  presents a schematic top view of one embodiment of the present invention similar to the view shown in  FIG. 1   b . This annular cylinder is radially truncated so that the annular cross section may be in the form of a semicircle. This annular cross section may comprise a major arc, wherein said major arc has an inscribed angle β of between 180 degrees and 270 degrees. Said major arc may have an inscribed angle β of between 200 degrees and 250 degrees. Said major arc may have an inscribed angle β of between 200 degrees and 230 degrees. This annular cross section may comprise a minor arc, wherein said minor arc has an inscribed angle β of between about 90 degrees and about 180 degrees 
       FIG. 2   b  presents a front schematic view of one embodiment of the present invention, similar to the view shown in  FIG. 1   a . This annular cylinder face comprises a longitudinal axis A 2  that lies perpendicular to the radial axis A 1  of the annular cross section. In one embodiment, fasteners are positioned along inner edge E 1  and outer edge E 2  of the face of said truncated annular cylinder. In one embodiment, fasteners are positioned along inner edge E 1 , outer edge E 2 , distal edge E 3 , and proximal edge E 4 . Fasteners  102  and  104  may be rivets, bolts, screws, or any other attaching means known to the skilled artisan. 
     As indicated in  FIGS. 2   a  and  3 , adsorption box  100  is defined by an inner radius R 1  and an outer radius R 2 . the truncated ends are defined by longitudinal cross-sections sections  111 , wherein said longitudinal cross-sections  111  are further defined by an inner edge E 1 , an outer edge E 2 , a distal edge E 3 , and a proximal edge E 4 . 
     As indicated in  FIG. 4 , adsorption box  100  is defined by a longitudinal annual cylinder length of L 1 . The truncated ends are defined by either a distal end E 3 , a proximal end E 4 , or both, having a width of L 3 . In one embodiment, the width of the distal end E 3  is unequal to the width of the proximal end E 4 . Also indicated in  FIG. 4 , permeable mesh barrier  103  is defined by a longitudinal length of L 2  and an axial width of L 4 . 
     As indicated in  FIG. 3 , according to one embodiment, an operative unit  107 , in this particular example the column, is supported inside the surrounding envelope  106 , in this particular example the cold box. The annular region  108  that includes the volume that is outside the operative unit  107  and still inside the surrounding envelope  106  is substantially evacuated. Adsorption box  100  is used to adsorb any humidity that may be present inside the cold box  106 , prior to lowering the pressure within this evacuated region  108 . 
     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.