Numerical simulation of condensation of sulfuric acid and water in a large two-stroke marine diesel engine

Abstract

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Mixed Flow Reactor Experiments and Modeling of Sulfuric Acid Neutralization in Lube Oil for Large Two-Stroke Diesel Engines

“…7,39 The condensation of H 2 SO 4 occurs in the gas phase just before reaching the lube oil film, where the temperature is lower than in the bulk gas phase. 6,47,48,56 Since no mixing is occurring, transport of CaCO 3 micelles to the H 2 SO 4 happens by diffusion. However, when the piston moves towards TDC (compression stroke, Figure 9(c)), the piston rings act to spread and remove excess lube oil from the cylinder liner.…”

“…Depending on the operating conditions, different concentrations of the H 2 SO 4 droplets can condense onto the lube oil film in a real engine application. 56 The range from concentrated (18·10 3 mol m -3 ) to very dilute H 2 SO 4 droplets (1.8·10 3 mol m -3 ) is therefore examined. Wu et al 21 found that the shrinking rate of acid droplets depends on the lube oil formulation, i.e.…”

“…However, despite the efficient mixing caused by the piston, the full lube oil volume in a cylinder cannot be approximated as a single mixed flow reactor. In the full-scale application, the lube oil film thickness varies vertically, 58 as does the H 2 SO 4 condensation rate, 56 because varying amounts of H 2 SO 4 may condense locally on the cylinder liners.…”

An experimental investigation of the corrosive influence of SO2 relative to H2SO4 of marine engine cylinder liners

“…The conversion may, however, be more than 4% in large low‐speed marine engines partly because of much lower engine speeds. In addition, advanced computational efforts indicate that H 2 SO 4 vapours will condense on the cylinder liners …”

“…In addition, advanced computational efforts indicate that H 2 SO 4 vapours will condense on the cylinder liners. 19,20 Cylinder lubrication oils used in large two-stroke marine engines contain alkaline additives (primarily CaCO 3 ) that neutralise acids. [21][22][23][24] The content of alkaline constituents is defined by the base number (BN).…”