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The present study investigates the corrosive influence of SO2 on cylinder liner wear relative to H2SO4. Several charge gases with different concentrations of SO2, H2SO4, and H2O in air are fed to a motored light duty test engine that operates at 98 revolutions per minute (rpm) in order to resemble the corrosive combustion gas and cycle speed of large low‐speed two‐stroke marine engines. When the trapped cylinder gas is compressed, the H2SO4 and H2O vapours can condense on the oil wetted liner surface, and the SO2 can be absorbed in the oil film. Hereby the liner surface may be exposed to a corrosive attack. A blend of a base oil and a commercial marine engine cylinder lubrication oil is used in the experiments. During testing, oil samples are extracted from the engine and subsequently analysed for iron and sulphur accumulation (using an energy dispersive X‐ray fluorescence spectrometer) in order to couple cylinder liner wear with the amount of SO2, H2SO4, and H2O in the charge gas. In contrast to H2SO4, the wear of SO2 is weak (if any), although the SO2 accumulates/reacts considerably in the lube oil. The highest wear rates are found at elevated H2O concentrations.

The work conducted in this paper presents a novel experimental setup to study sulfuric acid cold corrosion of cylinder liners in large two-stroke marine diesel engines. The process is simulated in a motored light duty BUKH DV24 diesel engine where the charge air contain known amounts of H2SO4 and H2O vapor. Liner corrosion is measured as iron accumulation in the lube oil. Similarly sulfuric acid condensation is assessed by measuring the accumulation of sulfur in the lube oil. To clarify the corrosive effect of sulfuric acid the lube oil utilized for experiments is a sulfur free neutral oil without alkaline additives (Chevron Neutral Oil 600R). Iron and sulfur accumulation in the lube oil is analyzed with an Energy Dispersive X-Ray Fluorescence (ED-XRF) apparatus. Three test cases with different H2SO4 concentrations are run. Results reveal good agreement between sulfuric acid injection flow and the accumulation of both iron and sulfur in the oil.

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