Effect of Syngas Composition on Metal Dusting of Alloy 800H in Simulated Reforming Gas Atmospheres

Abstract

Abstract The reactivity of various gas mixtures of carbon monoxide (CO), H2, carbon dioxide (CO2), and H2O was investigated in laboratory experiments to study metal dusting in simulated syngas environments of reforming plants. Quartz and Alloy 800H (UNS N08810) samples were exposed to eight gas mixtures of different CO, H2, CO2, and H2O composition at 650°C for 200 h. The amount of coke deposited from the gas mixture and the extent of corrosion were determined. Carbon deposition from the gas mixture onto the quartz and metal specimens was not understandable from the carbon activity, assuming thermal equilibrium of the entire gas mixture, but it was well interpreted according to the carbon activity derived from the gas reaction involving CO, H2, and H2O. Similarly, oxide scale thickness formed on the Alloy 800H specimen depended not on the oxygen potential by the thermal equilibrium, but on the partial equilibrium reaction of H2O and H2. This suggests that the gas mixture is not in an equilibrium condition...