Continuous KCl addition in high temperature exposures of 304 L – A way to mimic a boiler environment

High-Temperature Corrosion of P91/T91, 304l, Sanicro 28 and Inconel 625 Exposed at 600 °C Under Continuous Kcl Deposition

“…The experimental setup allows a continuous deposition of KCl during exposure and exhibits specific characteristics such as "low" and "high amount of KCl"-areas onto the sample surface, described in [21]. These labels were introduced due to the heterogeneous deposition of KCl onto a sample's surface.…”

“…The duration of the exposures was 24 h. Each exposure included 3 samples and was repeated at least twice in order to achieve reproducibility. More details about system robustness/reproducibility as well as a corrosion comparison of 304L exposed in this setup compared to exposure with ex-situ added KCl(s) and exposure in a 12 MW waste fired boiler is published in [21].…”

“…The resulting flue gas consists mainly of water vapor, CO 2 , hydrogen chloride and especially alkali chlorides [2][3][4]. Alkali chlorides are known for their corrosiveness towards superheater tubes [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. The current trend in utilizing more and more agricultural and forestry residues, waste wood, and other waste fractions instead of clean biomass (e.g., wood chips and wood pellets) makes this issue even more pronounced.…”

“…The "chromate formation" mechanism [6,7,[9][10][11]13,15,17,18,20,21,27] where the alkali initiates the corrosion attack of chromia forming steels, deteriorating the protective chromium-rich layer by the formation of alkali chromate. As the primary protection is lost, the resulting secondary oxide scale formed constitutes the steel's ability to withstand further corrosion.…”

“…In this study, four commercial alloys (T91/P91, 304L, Sanicro 28 and Inconel 625) were exposed to a harsh environment with continuous KCl deposition. A setup developed and presented in [21] was used in this study to mimic the continuous deposition of KCl(s) that occurs in biomass-and waste-fired boiler environment, simulating a KCl-rich environment,. The investigated materials were selected in such way that they represent a broad range of material classes: from ferritic/ martensitic stainless steel T91/P91 to the austenitic stainless steels 304L and Sanicro 28 to the nickel-based alloy Inconel 625.…”