| 摘要 |
PURPOSE:To keep the surface of an iron electrode active and to improve the efficiency in the generation of iron ions by appropriately maintaining an iron-based protective coating film formed on the surface to be protected by the action of a constant-potential circuit, and changing the polarities of the iron electrodes for supplying iron ions. CONSTITUTION:A DC current is supplied through a constant-current circuit 4 to a couple of the plate iron electrodes 2a and 2b of a composite iron electrode 2 provided almost in parallel with a water chamber wall. A voltage is impressed by the constant-potential circuit 6 with the positive side of the electrode 2 as the anode and the anticorrosive wall such as a tube plate 15 and a water chamber 1 as the cathode to deposit iron ions on the tube plate 15 and the inner wall of a cooling tube 17, and the iron film is formed on the surfaces. In this operation, the polarity of the electrode 2 is changed at specified time intervals by a polarity changing circuit 3 to prevent the formation of electrolytic scales on a cathode, then a switch 5 is actuated in linkage with the polarity change, and the positive side of the constant-current circuit 4 is always connected to the positive pole of the electrode 2. The potential of the tube plate 15 is detected through a check electrode 14 in the water chamber 1 to keep the potential of the tube plate 15 nearly constant. By this method, the effective surfaces of the iron electrodes 2a and 2b can always be kept active. |
