Anodic passivation of wetted wall vessels

Claim 1

A COMBINATION WITH A FLUID VESSEL HAVING INCLINED METALLIC WALLS ADAPTED TO HAVE A CONDUCTIVE, CORROSIVE LIQUID FILM FLOW DOWNWARDLY OVER THE WALLS AT A DEPTH; A CONTINUOUS CATHODE RING; NONCONDUCTIVE SUPPORT MEANS INTERCONNECTING THE WALLS AND THE CATHODE RING FOR SUPPORTING THE CATHODE WITHIN THE FLOWING LIQUID FILM, SAID MEANS ALSO SUPPORTING THE CATHODE RING IN UNIFORMLY SPACED RELATION TO THE WALLS AROUND SUBSTANTIALLY THE ENTIRE PERIPHERY THEREOF; A REFERENCE ELECTRODE DISPOSED IN THE LIQUID FILM AND ELECTRICALLY INSULATED FROM THE WALLS AND FROM THE CATHODE RING EXCEPT THROUGH THE LIQUID FILM; AND, ELECTRICAL CIRCUIT MEANS CONNECTED TO THE CATHODE, THE REFERENCE ELECTRODE AND THE METALLIC WALLS FOR MAINTAINING THE POTENTIAL OF THE WALLS AT A PREDETERMINED VALUE WITH RESPECT TO THE REFERENCE ELECTRODE BY PASSING A CONVENTIONAL DIRECT CURRENT FROM THE WALLS THROUGH THE LIQUID FILM OF THE CATHODE RING, WHEREBY THE POTENTIAL VARIATION OF THE METALLIC SURFACE DETECTED BY SAID REFERENCE ELECTRODE IS USED TO CONTROL BY MEANS OF THE ELECTRICAL CIRCUIT MEANS, THE POTENTIAL OF THE CONDUCTIVE SURFACE WITHIN THE PASSIVE REGION AND CORROSION OF THE SURFACE OF THE WALLS BY THE FLUID RETARDED.