GB817071A - Improved electrolytic cell - Google Patents

Abstract

817,071. Electrolytic cells. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. March 9, 1945 [March 15, 1944], No. 5999/45. Class 41. A cell for producing hydrogen and fluorine by electrolysing a molten hydrofluoric acid/alkali metal fluoride complex comprises a tank 1, at least two anodes 4 and at least two cathodes 6 alternating with the anodes in the tank 1, a tank cover comprising an outer member 2 and an inner member 3 which closes an opening in the member 2 adjacent the anodes 4, inner and outer gas chambers 30, 31 in the tank 1 respectively including the members 3, 2, and electrolytepermeable diaphragms 8, 9 which separate the anodes 4 from the cathodes 6 to prevent mixing of hydrogen and fluorine, the diaphragms 8, 9 being constructed and arranged to convey evolved hydrogen and fluorine separately to the chambers 31, 30. The anodes 4, which may be nickel or carbon, are supported in groups of three, Fig. 5, a space 13, Fig. 1, being left between adjacent rows of groups. Each group is suspended by a conductive lead 23 clamped between plates 5 embracing the tops of the anodes 4, the leads 23 passing through the member 3. The cathodes 6, diaphragms 8, 9, tank 1 and members 2, 3 may be of any metal, e.g. copper, iron or steel. The cathodes 6 are mounted between end-plates 7, Fig. 1, so that anodes 4 and cathodes 6 alternate, Fig. 5, the plates 7 being suspended by conductive leads 25 passing through the member 2. The diaphragms comprise plates 8 having openings opposite the anodes 4 in which are welded wire screens 9, each pair of plates 8 enclosing an anode 4 being connected at each end by plates 10 which, with the plates 8, are welded to a grid 11 which is bolted to depending partitions 29 on the member 2, each grid member 11 closing a cathode compartment at the top, Fig. 5. Electrolyte circulates on each side of the anodes and cathodes as indicated by the arrows in Fig. 1. The plates 8, 10 define anode compartments open at the top whereby fluorine passes to the chamber 30 and outlet 34, whilst hydrogen, prevented from rising by the grid 11 from the cathode chambers, passes to the chamber 31, the mesh 9 preventing intermingling of the evolved gases in adjacent compartments. Finelydivided carbon in a volatile binder which is evaporated by baking ensures good contact between the plates 5 and anodes 4. The leads 23, 25 pass through stuffing-boxes 12 containing insulation 32, and, in the case of the anodes 4, a non-conductive material 33, e.g. calcium fluoride, in a binder, e.g. Portland cement or sodium silicate. Hydrogen fluoride is supplied continuously or periodically by apertured pipes 36, and the electrolyte level in the tank 1 is indicated by a depending open-ended pipe which dips in the electrolyte and collects evolved hydrogen which is led to a pressure-responsive device, the hydrogen fluoride supply being regulated to maintain a constant level of electrolyte in the tank 1. A cooling jacket 39 is provided and may surround the bottom of tank 1. The Specification as open to inspection under Sect. 91 comprises also a modification of the above-described apparatus in which the anode compartments are closed at their bottoms by plates and the cathodes 6 are connected directly to the tank 1, the grid 11 being insulated from the partitions 29. Further, any metal may be employed as anode, the plates 10 may be omitted, and the diaphragms 8, 9 may consist entirely of woven wire screen or perforated plates. This subject-matter does not appear in the Specification as accepted.