Laboratory experiments for investigating high temperature corrosion in oxyfuel environments

In oxyfuel firing, fuel combustion occurs with oxygen and not air such that the resulting flue gas will be mainly CO2 + H2O. In addition there maybe recirculation of the flue gas thus any trace elements in the flue gas will increase in concentration as a function of time. The higher content of CO2 in the flue gas will make it more cost effective to recapture CO2 after combustion.

In addition, there will be a small percent of oxygen that will be used to enable combustion, however since oxygen is expensive; there is an incentive for a reduced input of oxygen. Based on a need for more information on corrosion processes in the oxyfuel environment, laboratory experiments were conducted for two austenitic steels (TP347H FG and Sanicro 28).

Steel specimens cut from tubes were exposed in a carbon dioxide containing environment at 600°C and 700°C for up to 334 hours. Specimens were exposed in air, CO2, CO2 +46%H2O and CO2+46%H2O+1%O2. The growth and morphology of the oxide and its effect on possible carburisation of the steel was investigated using light optical microscopy.

Comparison of the influence of the various environments is discussed.