Experience of superheater tubes in municipal waste incineration plant

Two years after the start of operations at the Tokachi Association for Municipal Waste Disposal and Treatment Services municipal waste incineration plant (name: Kuririn Center), which generates 400°C steam, an investigation of the plant's superheater tubes was conducted. The investigation consisted primarily of analyzing ash deposits, measuring tube wall thickness loss and observing tube sections after removal. The concentration of Cl in the deposited ash was found to increase as the temperature of the gas rose, and the amount of deposited ash tended to increase as the temperature of the gas rose. Tube damage consisted primarily of a uniform loss in thickness. Intergranular corrosion and other local corrosion was not observed. The results of thickness-loss measurements showed that, after approximately two years in operation, tubes (SUS310) lost a maximum of 0.45 mm in thickness due to high-temperature corrosion in locations where the steam temperature reached 400°C. Superheater tubes were also apparently damaged from the effects of a soot blower, resulting in an observed maximum loss of 0.9 mm thickness after approximately two years. Furthermore, the rate of thickness loss tended to increase after one year had passed.