Anodic corrosion protection of sulphuric acid plants with regard to the recovery of heat

Anodic protection makes it possible to keep materials which can be passivated in a “passive” state or to bring them into this state, even in unfavourable conditions. With sulphuric acid concentrations of 93–99% this method permits the use of inexpensive, stainless austenitic steels, e.g. 1.4541 and 1.4591, at temperatures of up to 160 °C. The temperature range from 120 °C to 160 °C, in particular, is suitable for heat recovery. Anodic protection by the APR‐system provides safe and low‐cost protection for air coolers and bare tube coolers in sulphuric acid plants. The results of laboratory, pilot plant and commercial trials show that in this way a safe operation of sulphuric acid coolers is possible on a long‐term basis.