Abstract:
The invention concerns an installation for emptying casks ( 1 ) equipped with an external bag ( 11 ) and an internal bag ( 12 ) containing powdery products. It comprises a glove box ( 12 ) consisting of a bell made of a transparent material. It is provided, on its upper part, with an opening for the passage of a suction rod ( 3, 31, 32 ) equipped with sealing means between said pipe and the bell. The lower part of the bell is provided with means adapted to be urged in sealed position on the upper part of a cask ( 1 ). The bell ( 2 ) is suspended to a frame ( 5, 15 ) for its vertical displacement.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an installation for emptying casks equipped with a double internal bag comprising an outer bag and an inner bag containing powdery products and to a method for using said installation. 
     PRIOR ART 
     For the chemical industry, and more particularly the pharmaceutical industry, the confinement of products has always been a fundamental problem. During the last ten years, the products used by this industry, in particular powdery products, have been constantly increasing in their toxicity and in their reactivity. Furthermore, the production standards relating to quality result in the confinement of such products being unavoidable. 
     Confinement is also a necessity for both ecological reasons and for protecting the health of operators and, furthermore, to prevent the product from coming into contact with the ambient atmosphere and being contaminated. The operators have, up until the present time, been protected by clothing and gas masks or similar apparatuses. However, this solution is not satisfactory because is makes manipulations difficult and unpleasant. Furthermore, this solution protects neither the products nor the environment: it is therefore necessary to make use of more sophisticated systems. In such systems, complex ventilation and filtration systems are often resorted to. Installations comprising glove boxes have been used. A glove box is a closed enclosure provided with openings leading to the inside of gloves through which the operators try to manipulate the product that are inside a cubicle, for example by taking a cask, emptying it into another device for the manufacture of a product or for transferring it by means of an appropriate installation to a precise place. This type of installation is extremely costly and the manipulations of the casks is rather difficult using installations with gloves which, of course, make satisfactory confinement possible. This type of installation, called an isolating installation is not necessarily the best solution particularly when the powder must be loaded into an item of equipment such as, for example, a reactor, a dryer, etc, whose accessibility is poor and it is difficult to place such an isolating installation above the apparatus or the machine. 
     SUMMARY OF THE INVENTION 
     The purpose of the present invention is to propose an installation combining the advantages of a glove box and a powder transfer system in order to carry out such operations whilst ensuring the confinement of the product and also the protection of the operator and of the environment. 
     The invention also relates to a method of using this installation. 
     The installation for emptying casks according to the invention is characterized by the characterizing clause of claim  1 . 
     The advantage of the installation according to the invention is the fact that, on the one hand, it is easy to place a glove box, which has already proved itself, on a cask provided with two internal bags, one of which is outside the other, to use a suction rod for sucking up the product and, consequently and still by manipulating through the glove box, to put another cask in place of the first one and to use it in a very flexible manner. 
     According to a variant embodiment, the lower part of the bell comprises a flat surface fitted on its lower face with a flat seal making it possible, during the positioning of the glove box on the cask, to ensure the sealing between the two of them, said flat surface being provided with an annular opening formed from a holding ring provided with means of holding the upper part of the bags. 
     The method according to the invention is defined in claim  6 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in greater detail with reference to the appended drawings. 
         FIG. 1  is a diagrammatic side view of the installation according to the invention. 
         FIG. 2  is an enlarged view of the bell placed on a cask. 
         FIGS. 3-13  are partial views of the installation illustrating the stages of the method. 
         FIG. 14  is a plan view of the bell. 
         FIG. 15  is a cross-sectional view of two filters. 
         FIG. 16  is a diagrammatic view of the cleaning device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a cask containing the powdery product to be emptied, the bell  2 , the suction rod  3  and a support chassis  5 . 
     The cask  1  comprises, inside of it, two bags  11  and  12 , in principle made of a plastic material, each one closed independently: the bag  11  will be called the outer bag and the bag  12  will be called the inner bag. These two bags make it possible to confine the powdery product even after opening the cask, that is to say after having removed its lid. The glove box  2  is fixed to a support  51  of the chassis  5  which can be displaced in the vertical direction. The suction rod  3  is suspended by a flexible link  52  and a pulley  53  from the chassis  5  in order to allow the withdrawal of the rod or its insertion during the various stages of the method. The chassis  5  has a flat surface provided with rollers  54  facilitating the displacement of the casks and in particular their positioning under the glove box  2 . 
     The suction rod essentially comprises a pipe  31  connected to a suction device making it possible to transfer the product from the cask to another reservoir or directly into the reactor or device in which the product must be used. The pipe  31  is surrounded by a flexible sleeve  32  closed at its upper end and being connected in a sealed manner to the upper part of the glove box  2 , as will be seen below, thus making it possible to ensure the sealing of the installation. 
     Reference will now be made to  FIG. 2  in order to describe the glove box in detail. The glove box comprises a bell-shaped part  21  made of a transparent material, for example acrylic glass, through which the operator can see and monitor the emptying operations. It is also possible to have a bell made of stainless steel fitted with a part made of transparent material to make it possible to see inside the bell during its use. Two openings  22  placed on the side surface of the bell make it possible to install gloves fitted in a sealed manner into these openings which allow the manipulation of the various items inside the bell. The upper part of the bell is provided with an opening  26  through which passes the suction rod  3  and, in particular, the pipe  31 , while the flexible sleeve  32  is fixed in a sealed manner onto the upper part of the opening  26 . It is possible, in an optional manner, to provide this opening with a valve  27  in order to be able to close it when the rod, and in particular the pipe  31 , are in a separated position such as shown for example in  FIG. 1  or  2 . The lower part of the glove box has a holding ring made of stainless steel  24  forming an annular opening on the lower part of the bell  23  which is flat. The flat surface  23  is provided with a flat seal via which it is placed on the upper part of the cask. The radial width of this flat surface makes it possible to adapt the glove box to casks whose diameters may be different, the essential point being that the bell can stand on the upper edge of the cask via the flat seal thus ensuring sealing. The ring  24  is provided with one or two retaining rings  25  which will be used for holding, as will be explained below, the two bags  11 ,  12  located inside the cask  1 . The glove box is provided with a fixing device  28  by means of which this glove box is connected to the vertical displacement device  51  of the chassis  5 . 
     The method of using this installation will now be described with reference to  FIGS. 3  to  13 . The operator starts by removing the lid from the cask  1 , opening the outer bag  11  and slipping a disposable sealing ring  6  ( FIG. 4 ) inside. The sealing ring  6  is positioned inside the holding ring  24  and the outer bag  11  is opened ( FIG. 5 ) by removing the flexible tie. Up until this stage, no contact with the product located inside the cask is possible since the inner bag  12  is still closed. Subsequently, the glove box  2  is lowered onto the cask, as shown in  FIG. 6 , and the operator places his hands in the gloves of the glove box in order to remove the upper part of the bag  11 ′ that remained during the emptying of the preceding cask and to throw it through an opening  29  of the bell and into a sack. In order to continue, the upper edge of the outer bag  11  is fixed to the holding ring  24  by means of an O-ring (FIG.  2 ). Then he opens the second bag  12  ( FIG. 7 ) and he throws the flexible tie through the opening  29  and ensures that the upper part is also held over the holding ring  24  with the same O-ring or with a second one. From this moment, the product can be sucked up, which is carried out by lowering the suction rod ( FIG. 8 ) and by guiding it inside the cask in order to be able to suck up the product from the smallest recesses to be found inside. The operator, during this phase, manipulates the suction rod without being in contact with the product which is confined inside the glove box-cask installation and without wearing special clothing or equipment. 
     When the cask is completely empty (FIG.  9 ), the rod  3  is raised and the operator inserts his hands in the glove box ( FIG. 10 ) and releases the upper part of the inner bag  12  which falls inside the outer bag  11  together with the disposable ring  6 . Then the suction rod and glove box assembly ( FIG. 11 ) is raised up to a certain height making it possible to have access to the upper part of the outer bag  11 . Using two ties (FIG.  12 ), the upper part of the bag  11  is tied at two places separated in the vertical direction and the bag is then cut between the two ties (FIGS.  12  and  13 ), which makes it possible for the lower part of the bag  11 , which is closed, to drop inside the empty cask while the upper part of the bag  11 , also closed and isolated, remains on the ring  24 . No leakage of the product is able to contaminate either the operator or the environment of the installation. 
     Subsequently, the empty cask is taken away and a new cask is brought in and the same operations as before ( FIG. 2  onwards) are started again. 
     When the product to be transferred contains solvent or when it can react on contact with air or with moisture, the installation can be placed in a nitrogen atmosphere. 
     In order to ensure that work is carried out inside the installation under a slight depression, the bell  2  ( FIG. 14 ) is provided with two openings on the side surface provided with two smooth tubes  7 ,  8 . Each tube is provided with a filter  71 ,  72  fitted in a sealed manner. By means of a ventilation circuit, a flow of air (or of nitrogen if appropriate) is provided between the two filters in order to create a slight depression inside of the installation and to avoid any leakage of the product in the event of a manipulation error or another problem. These filters  71 ,  72  are standard filtering cartridges of the “push through” type, that is to say it suffices to push the new cartridge onto the old one in order to position it, the old one falling into the glove box so that it can be removed through the opening  29 .  FIG. 15  partially illustrates the flow of air (or of nitrogen) through the filters  71 ,  72 . 
     Finally,  FIG. 16  is a diagrammatic representation of a system for cleaning the installation, that is to say the bell and the rod. There is positioned a cask  8  provided with an inlet  81  for the cleaning liquid followed by a hose  82  whose end carries a spray gun  83 . The cask  8  comprises a drainage opening  84 . The bell is placed on the cask  8 , the ducts of the two filters are closed and cleaning is carried out by spraying. To clean the rod  3 , the cleaning liquid is made to flow between the cover  32  and the pipe  31 . After the cleaning, the liquid is drained into a pit or a suitable container. 
     The installation described is very flexible as it can be moved and used with different equipment. Furthermore, it is possible to install it on a weighing device thus making it possible to check the quantity of product sucked up. 
     The glove box can easily be adapted to different diameters, or even different cask geometries by changing the face  23 . 
     Depending on the product to be transferred, it is possible to carry out the transfer in an inert atmosphere. 
     Although illustrative embodiments of the invention have been shown and described, a wide range of modification, change and substitution is contemplated in the foregoing disclosure and in some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.