Patent GB-779928-A (GB)
Title: Improvements in or relating to electrolytic cells
IPC: C25B9/19
Filed: 1955-06-10
Abstract: 779,928. Electrolytic cells. COLUMBIASOUTHERN CHEMICAL CORPORATION. June 10, 1955 [July 12, 1954], No. 16735/55. Class 41. An electrolytic cell, e.g. for electrolysing brine to produce sodium chlorate or caustic soda and chlorine, comprises a vessel having a bottom 20 and side walls and a plurality of cathode structures spaced along the vessel, each structure having an end section 40 extending transversely of the vessel and dividing the vessel into a number of units A ... E and having spaced cathode fingers 38 extending from each section 40 longitudinally of the cell and terminating short of the section 40 of the adjacent cathode, electrically conductive covers 26 for each unit insulated from the corresponding cathode, anodes 28 depending from each cover 26 into the spaces between the fingers 38, and means for electrically connecting each cover 26 to the section 40 of the adjacent unit. The sections 40 are hollow and of metal and are divided into two compartments 42, 43, cooling water entering at 56, flowing through the hollow metal fingers 38 which contain baffles 54 and leaving at 58. The anodes 28 are graphite and the covers 26 are graphite or steel, the lower face being then covered with thin rubber. Each section 40 rests on a partition 32 and at the top is bolted at 82 to the cover 26 of the succeeding unit, a lateral rib 80 on the cover engaging a groove 72 on the top 70 of the section. Adjacent covers 26 are separated by insulators 84 and putty 86. Copper strips 126, 128 on the first and last units A, E respectively serve as current leads. Brine enters each unit at 112 and sodium chlorate solution leaves by an aperture at the bottom on one side. Air is delivered to each unit, and a mixture of air and gases leaves each unit by holes in the covers 26. Each cathode is insulated from the electrolyte in an adjacent unit by hard rubber 60. In a modification, Fig. 8, each finger 221 comprises a metal member 222 having dimples 223 and carrying a woven wire screen 224 coated on the anode side with asbestos. The fingers 221 lie between anodes 208 and are integral with a hollow section which is apertured top and bottom to permit escape of hydrogen and caustic soda respectively, the hollow interior of the section having outlets at each side, Fig. 7 (not shown), for these products. A conduit 264 welded to the side wall 204 of the cell communicating with the anode chamber serves as an outlet for chlorine. In the above embodiments, the side walls, e.g. 204, of each unit are bolted together through abutting flanges with insulation, sandwiched between; and in the second embodiment, the bottoms of adjacent units are similarly secured together, rubber. 238 overlying the bottoms. In another embodiment, Fig. 11, each cathode section 302 has three walls 322, 323, 324 welded together and rods 328, 330 welded to wall 322 support corrugated metal members similar to members 222 of the previous example. A woven wire screen 332 supporting asbestos in its interstices is welded at each end to each side wall of each unit where the wall 322 meets the side wall, and intermediate its ends is formed into a number of deep, narrow, vertical undulations separately to enclose each cathode metal member which is thus separated from the anodes 308. Brine enters each unit at 346. Chlorine and hydrogen leave respectively by outlet 340, pipe 342 and outlet 336, pipe 338, the outlets 336, 340 being in the same side wall of the unit, whilst caustic soda solution leaves the unit by a pipe at the bottom of the opposite side wall. Each cover 306 comprises a number of sections side-by-side, resting at one end at 350 on the unit it covers and bolted at 360 at the other end to the preceding cathode section wall 324, the rib and groove of the previous embodiments being dispensed with. Each side wall is flanged at each end and at the bottom for bolting to adjacent units and to a base 300, rubber 325 insulating the units, and the base 300 is flanged at each end at 312, 314 for bolting to an adjacent base.