| 摘要 |
PROBLEM TO BE SOLVED: To prevent stress corrosion crack or corrosion fatigue due to occurrence of dew point corrosion of metal by making a decision whether the concentration of hydrogen ion in an ash deposited on the surface of a metal to be measured increases acceleratedly with time. SOLUTION: The concentration of hydrogen ion in an ash deposited on the surface of an object to be measured, i.e., a heat transmission metal pipe 1, is measured by means of a sensor 3 and a measuring section 4. Based on the measurement and a measuring period Δt, a reaction rate constant (k), a cathode factor g2 and an anode factor (f) stored ion an input section 5, an operating section 6 performs specified operations at a period Δt and indicates 7 the variation of hydrogen man concentration with time. The measured hydrogen ion concentration is then compared with a value measured previously and a decision is made that dew point corrosion has occurred it the concentration is increasing acceieratedly and then an alarm 8 is delivered. At the same time, a waste heat recovery boiler is restarted or a required part is heated by means of a heater to elevate the temperature of deposited ash 2 above dew point thus preventing progress of corrosion. |
