Studies on the Partial Reactions Between Potassium Chloride and Metallic Chromium Concerning Corrosion at Elevated Temperatures

Recovery of energy from biomass by combustion has become important due to reduction of detrimental CO2 emissions. It has been suggested that the reaction between KCl released during combustion and the protective Cr2O3-layer is the one responsible for starting the complex series of corrosion reactions. In this work, the overall reaction between KCl and Cr was studied through reactions with compounds such as Cr2O3, K2CrO4, and K2Cr2O7 known to participate in the overall reaction or to be formed during it. The reactions were studied in synthetic air with a DTA/TGA apparatus. Under the conditions studied, both KCl and K2CrO4 reacted with pure, metallic Cr as well as with Cr2O3. In the case of Cr, Cr2O3 was formed via the formation of K2CrO4. In reactions including Cr2O3 as reactant also K2Cr2O7 was detected. However, when used as a reagent, K2Cr2O7 reacted with neither Cr nor Cr2O3.