METHOD AND DEVICE FOR PREVENTING CORROSION IN EVAPORATOR TUBE AND SUPERHEATER TUBE

摘要

PROBLEM TO BE SOLVED: To provide a method and a device for effectively preventing corrosion in an evaporator tube and a superheater tube of a vertical boiler and a vertical exhaust heat recovery boiler at a relatively low cost.;SOLUTION: In order to prevent the inner surface corrosion due to water quality of a heat conductive tube used in a horizontally arranged evaporator and a superheater, the boiler water is evaporated for concentration at the same temperature with the evaporators 5 and 6 and the superheater 7 to solidify the sodium phosphate salt for deposition (hyde-out), corrosion of the boiler water is monitored on the basis of pH of the residual solution and concentration of phospholic acid ion. Addition quantity of the can cleaning agent and Na/PO₄ ion mole ratio of the can cleaning agent are controlled to regulate pH of the residual solution and concentration of phospholic acid ion within a range at 9.5-10.2 pH and concentration of PO₄ ion within a range at 2-20 mg/L.;COPYRIGHT: (C)2003,JPO