Abstract
The aim of this work is to extend the lower limit of operating temperature of the high-temperature corrosion monitoring sensor for boiler tubes in waste incineration plants. The lower limit of operating temperature depends on the solidifying point of the electrolyte solvent of the Ag/Ag^+-type reference electrode of the sensor. The researchers obtained a modified reference electrode with a lower operating temperature by changing the electrolyte solvent from equimolar NaCl-KCl-Na_2SO_4 to 44 mol% NaCl- 56 mol% ZnCl_2. The field test in a waste incineration plant has been performed to investigate the applicability of the improved sensor. In the test, the corrosion rate of the SUS 310J1 stainless steel was measured by electrochemical impedance method at 30-minute interval, and the state of measurement was monitored by wireless communication equipment for 2,087 hours. As the result, the corrosion sensor proved to be suitable for measurement in the temperature range down to 280℃. The observed data provides the contour map of corrosion rate represented in the T_<metal>-T_<gas> coordinates, which is useful for the structural design and material selection for the boiler superheaters.
