Tuesday, January 7, 2020

Liner Lacquering

  • Occurs in medium speed engines.
  • Build up of lacquer on liner grooves -Glazing due to which cylinder LO consumption increases.
  • If left unnoticed - Scoring \ polishing of liner and operating cost of engine

Because of 

1. Large variation of load \ frequent \ prolong perios of idle running followed by full load.
2. High mean effective pressure
3.Low sulphur

How?

The time for injection  , injection and combustion is very small.
Therefore beside complete combustion , thermal cracking of fuel component can be expected .
If these cracked component reach relatively cylinder liner , they will condense , concentrate and start formal sticky resinous lacquer of process of polymerization and evaporation of light ends
  1. Fuel droplets injected at HP begins to burn rapidly
  2. Rapid burn leads to incomplete combustion of some layer fuel droplets but intense heating of droplet corresponds
  3. Thermal cracking of some fuel components occurs within larger drop.
  4. Some droplets impinging on cylinder liner where thernal cracking reaction c ontinuse to form unsaturated reactive ydrocarbon
  5. Condensation and polymerisation of unsaturated products of the liner forms resinous organic polymeric deposit.
  6. Sticky resinous deposit is spread over te liner by piston ring movement.
  7. Lubricant including metal - containing additives beconmes entrained in the deposit.
  8. Continual dexposure of the deposit to combustion , evaporation of light ends and rubbing by piston movement forms hardened lacquer deposit.
  9. Build up of lacquer fills honing grooves and leads to increased rate of oil consumption

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