Corrosion of T-11 syngas cooler tubes in IGCC pilot plant

Measurements of wall loss of syngas cooler tubes (T-11) were done in an IGCC pilot plant which was operated 4700 hours for 6.25 years. The corrosion rate is pseudo-linear and the total loss is 3.2 mm max. The scale formed consists of the layers of iron sulfide and oxide. The corrosion loss is too large for high temperature corrosion only at tube skin temperature of 230–250°C. The syngas cooler was opened to air for the shutdown time of about 59000 hours. Therefore, it is concluded that the downtime corrosion strongly contributed to the loss of tube wall in this test plant.