Fluent material handling – with receiver or receiver coacting mea – Filling or refilling of dispensers – Aerosols
Reexamination Certificate
2000-04-04
2001-09-25
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Filling or refilling of dispensers
Aerosols
C141S003000, C141S302000
Reexamination Certificate
active
06293316
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of filling a container that is closable by a lid; the container is filled with a powder. The invention also relates to transfer apparatus associated with said method, which apparatus can be described as a “filler head”.
Above, and below in the present text, the apparatus associated with said method of filling is referred to as “transfer apparatus”. In any event, said transfer apparatus serves to guide and confine the powder which falls under gravity.
2. Description of Related Art
Said method and apparatus have been developed for the purpose of enabling a powder to be transferred while avoiding any dissemination of said powder outside said apparatus and while avoiding any accumulation of said powder within said apparatus.
Said method and apparatus are particularly suitable for discontinuous transfer of toxic powders, and in particular radioactive powders.
To resolve the technical problem involved, i.e. that of transferring a powder into a container for the purpose of filling the container while avoiding any dissemination of the powder, there exist known apparatuses and in particular apparatuses comprising a tubular body which defines a chamber that can be closed at its bottom end by a valve.
The body is provided with a docking port for receiving the container which is generally closed by a lid. Said port is consequently fitted with means for taking hold of said lid.
A powder-feed duct opens out into the top of the chamber.
After the container has been docked and its lid removed, the valve is opened to put the chamber into communication with the inside of the container.
The powder then flows into the container through the chamber.
To limit the risk of powder being disseminated to the outside, a small degree of suction is maintained in the inside volume of the entire apparatus by means of a ventilation system. The ventilation gas is extracted via a filter column in order to retain the powder entrained thereby.
Such apparatus, although effective, nevertheless leaves zones in which powder accumulates (valve, docking port, . . . ) which can lead to said powder becoming disseminated in operation; and the danger of such dissemination increases with increasing toxicity of said powder.
SUMMARY OF THE INVENTION
Faced with this technical problem, the invention proposes a method and associated apparatus for transferring powder into a container, in which implementation of the method and the apparatus serves to avoid both any leakage of the powder to the outside and any accumulation thereof within the apparatus.
In a first aspect, the invention thus provides a method of filling with powder a container that is closable by a lid. Said method comprises using transfer apparatus which includes a powder-feed duct for feeding said powder and means for putting said duct into communication with the inside of said container. In said method, in characteristic manner, during filling:
the powder passes vertically downwards through the transfer apparatus and, downstream from said powder-feed duct, it does so in a lined well; such lining protecting the internal mechanical parts of said apparatus;
a small level of suction is maintained inside said apparatus, including inside at least the bottom end of said powder-feed duct, in order to provide continuous ventilation and thus avoid any powder accumulating and any powder being disseminated to the outside.
In said method of the invention, both the external surroundings and the internal mechanical parts of the transfer apparatus are effectively protected from said powder: any dissemination of said powder is prevented because of the lining. In addition, because of the ventilation, said internal mechanical parts are protected better. Dynamic confinement is achieved by entraining into filter assemblies all traces of said powder that might accumulate. Naturally said ventilation must be performed with controlled intensity that is compatible with allowing the powder to drop under the effect of gravity.
The person skilled in the art will already have understood the advantage of the method of the invention for transferring a toxic powder into a container, and in particular a powder that is radioactive. The Applicant has specifically developed this method and the associated apparatus for the purpose of filling cylinders for packaging PuO
2
powders.
In the context of the method, it is advantageous for the ventilation which serves to provide dynamic confinement to be implemented as two mutually independent circuits.
The transfer apparatus including, from top to bottom:
the vertical duct for feeding the powder;
a spherical valve having a through cylindrical passage; and
a case enabling the container without its lid to be docked, said case containing means for temporarily retracting said lid, the said two independent ventilation circuits are situated respectively in association with said powder-feed duct and in association with said docking case. The first is referred to as the “top” ventilation circuit, and the second as the “bottom” ventilation circuit.
In both of these top and bottom circuits, ventilation is provided continuously throughout the duration of transfer (i.e. while the powder is actually passing through the transfer apparatus), and also before and after said transfer, while the internal mechanical parts of the transfer apparatus are being arranged and rearranged. Arrangement is for the purpose of putting the powder-feed duct into communication with the inside of the container, while rearrangement is for the purposes of interrupting said communication and allowing the full container, as closed by its lid, to be withdrawn.
In general, ventilation is provided continuously throughout a period of operation during which n containers are filled. Ventilation can be stopped during two such successive periods of operation . . . , however given the nature of the powders transferred, it may be preferable to opt for ventilation through the transfer apparatus to be genuinely continuous.
Said ventilation is advantageously implemented in the bottom circuit in two different modes of operation in succession.
One of said modes of operation serves specifically to sweep the zone in which the retracted lid is received, and in particular to sweep the bottom face of said lid. Such sweeping is performed at the end of transfer.
In case it needs to be said, it is specified at this point that the ventilation within the apparatus of the invention is not “forced” ventilation using air that has been blown, but is ventilation that results solely from maintaining a small amount of suction inside the apparatus. Said ventilation is provided by the surrounding atmosphere being sucked in through admission orifice(s) provided for this purpose in the structure of the apparatus.
In a second aspect, the invention provides apparatus for transferring a powder into a container that is closable by a lid. Such apparatus, which can exist in several variants, is adapted to implementing the above-described method. In characteristic manner, said apparatus comprises:
in a top portion, a vertical powder-feed duct for feeding said powder, said duct being surrounded by a cylindrical sleeve over a certain height starting from its bottom end; said duct and said sleeve thus defining an annular space that is closed at its top end; said duct being suitable for being connected in the vicinity of its top end to apparatus for feeding it with said powder;
in a bottom portion, a case provided firstly with means for taking hold of the lid of the container, for retracting it, and for putting it back into place, and secondly with a vertical cylindrical recess that is open at its top and bottom ends, the shape of said recess enabling it to dock with the top portion of the container without its lid;
a spherical valve having a through cylindrical passage placed between said case and the bottom end of said vertical duct, and suitable, when in the open position, for putting said vertical duct into communication with the inside of sai
Bertolotti Gérard
Defontaine Bernard
Compagnie Generale des Matieres Nucleaires
Dennison, Scheiner Schultz & Wakeman
Douglas Steven O.
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