NITRIC ACID SOLUTION TREATMENT SYSTEM FOR EVAPORATOR

PURPOSE:To extend the working life a evaporator, by incorporating a nitric acid solution containing Ru and Fe with a reducing agent capable of reduction of RuO4 into RuO2 followed by removing the RuO2 together with the Fe using an electromagnetic filter to prevent the evaporator from corrosion due to ruthenium oxide. CONSTITUTION:A nitric acid solution containing Ru and Fe flows, through a pipe 15, into a bottomed cylindrical liquid flow direction-regulating member 17 with many holes on the wall, when a reducing agent capable of reduction of RuO4 into RuO2 (e.g. NO gas) is incorporated through a reducing agent- injection line 16. As a result, the volatile RuO4 in the nitric acid solution, capable of inducing corrosion of structural materials, reacts with the reducing agent (e.g. NO gas) to form a solid RuO2. Taking advantage of the fact that this RuO2 is solid, the flow direction is changed through the above-mentioned many holes on the member 17 to afford the RuO2 with inertia force, thus making the RuO2 impinge on the adsorption surface of an electromagnetic filter 18. On this surface, a ferromagnetic iron has been adsorbed, having characteristics ready to scavenge the solid RuO2, thus resulting in elimination of this RuO2 by the electromagnetic filter 18.