Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
2000-01-20
2001-10-30
Gorgos, Kathryn (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S253000, C204S252000
Reexamination Certificate
active
06309522
ABSTRACT:
This invention relates to an electrolytic cell and in particular, but not exclusively, an electrolytic cell for the production of chlorine gas by electrolysis of hydrochloric acid.
A known design of such a cell is a series of planar electrodes suspended in a circulating electrolyte across which a voltage is applied. A membrane is supported to cover each electrode to provide separation of the hydrogen and chlorine gas produced by the electrolysis of the electrolyte, which gases are then separately extracted from the cell.
The heat produced by the electrolysis process is removed from the cell by the circulation of the electrolyte but will still subject the cell components to a range of operating temperatures in a given work cycle.
Such a stack of electrode/membrane components has been formed by stacking a series of frames interposed between the electrodes and membranes to form sealed interfaces with them, and to form common manifolds for transporting the electrolyte to and from the electrodes and membranes of the cell sealing being obtained by applying pressure to the stack by clamping them together. A disadvantage of this approach is that all the seals are, in effect, fully formed at the same time as the pressure is applied to the stack and failure of one seal can mean having to reassemble a large part or all of the structure. Particular difficulty is associated with the formation of the manifold seals a construction requires the components to be manufactured to close dimensional tolerances. Thermal cycling also introduces physical stresses that can prejudice seal security during use of the cell.
The present invention, in a first aspect, seeks to provide an electrolytic cell which can be securely assembled from elements with reduced dimensional tolerances and less prone to disturbance when thermally cycled. Accordingly there is provided an electrolytic cell including a first and a second, generally planar, membrane-supporting frame each having a plurality of through-holes and each sealed to a plurality of annular coupling members located between the frames and generally coaxially with a respective through-hole of each frame to thereby define a plurality of sealed conduits through the frames and each coupling member is attached in a sealed relationship to the first frame so as to be capable of movement parallel to the plane of the first frame during assembly of the cell and is sealed to the second frame at a cylindrical interface which provides sealing over a range of distances between the first and second frames.
The frames of the cell of the present invention may be intercoupled by a method according to a second aspect of the present invention which includes the steps of: mounting the second frame in a partially formed electrolytic cell; attaching the plurality of coupling members to the first frame so as to form a seal between each coupling member and the first frames; adjusting the position of the coupling members on the first frame so the plurality of coupling members can be engaged in a sealed relationship with the second frame; and sealing engaging the plurality of coupling members with the second frame thereby forming the plurality of sealed conduits.
The seals between the coupling members and the first frame are securely formed on attaching the coupling members to the frame prior to mounting in the part assembled cell. The first frame and coupling members are then offered up to the second frame with any slight dimensional differences in the plane of frames being accommodated by lateral movement of the coupling members on the first frame.
As will be described in more detail below, an electrode may be sealed between the first and second frames whose thickness will determine the distance between the frames. As the coupling members attached to the first frame are sealed at a cylindrical interface which provides sealing over a range of inter-frame distances, sound sealing is obtainable over a range of electrode thicknesses so lowering the need for high tolerances in the production of the electrode also.
The conduit formed by the through-holes and annular coupling member are part of common manifolds in the assembled cell. It will be appreciated that each manifold is formed fully sealed in stages as the frames are mounted in the cell.
The coupling member may include a ring seal at an annular interface between the coupling member and the first frame and in which the ring seal is retained in an annular groove in the coupling member, for example.
The cylindrical interface may be formed between a radially inner cylindrical surface of the coupling member and a radially outer surface of a circular wall of the second frame and in which a ring seal is retained in a circular groove formed in the inner cylindrical surface of the coupling member, for example. Such a circular wall is conveniently defined by an annular recess formed about a through-hole of the second frame.
Preferably, each coupling member is attached to the first frame by a plurality of threaded fastening members located in oversize through-holes formed in the annular recess of the first frame and threadingly engaged with the coupling member. For example, the threaded fastening members may be bolts and the heads of the bolts located at least partially within an annular recess of the coupling member.
Preferably, the frames and coupling members are formed of the same material in order to provide thermal matching of the components.
The electrolytic cell of the present invention has elements which can be simply machined and assembled as the claimed construction removes the necessity for very tight tolerances on both material supplies and machining.
REFERENCES:
patent: 4210511 (1980-07-01), Campbell
patent: 4233146 (1980-11-01), Rothmayer et al.
patent: 4463064 (1984-07-01), Ruch et al.
patent: 4886586 (1989-12-01), Morris
patent: 4898653 (1990-02-01), Morris
patent: 0056503 (1982-07-01), None
patent: 2280433 (1976-02-01), None
patent: 8100863 (1981-04-01), None
Routh Julian Dudley
Strutt Ivan
Capital Controls Ltd.
Engellenner Thomas J.
Gorgos Kathryn
Nguyen Tram Anh T.
Nicolas Wesley A.
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