Abstract
Metallic materials selected for the construction of in-bed heat exchangers in fluidized bed combustion (FBC) systems must withstand the corrosive conditions prevalent in these systems. The corrosion behavior of carbon steel, chromium-molybdenum ferritic steels, Type 310 stainless steel, and Incoloy 800 has been evaluated after exposure to complex gas mixtures that simulate conditions anticipated in FBC systems. Experiments have been conducted on internally cooled tube specimens with metal temperatures of 977 and 866 K and gas temperatures in the range 999 to 1123 K. Results are presented on the gas-metal interactions and the scale morphologies as a function of gas chemistry, alloy type, and system temperature. Experimental results are also presented on the corrosion behavior of candidate materials coated with deposits such as CaSO4, CaO, and CaO/CaSO4 mixtures. The information has been used to examine the effects of the type of deposit and deposit sequence on the scale development and grain boundary penetration of oxygen or sulfur in the substrate material.