Ask Dr. Vis

• EMISSIONS
• Par Lundqvist
  Q-comb
  GMT 14:07
  15th Nov 2007

  Whats the different between soot and coke formation? Any or just the same? If different, how can it be two type of "soot" in combustion (in diesel engines slow or medium speed types) comming from the same quality of bunker? If thers soot and or coke is there any different how they effect the engine? Can the better MDO in combustion in a diesel engine give any soot/coke formation? Any differens between a heavy 380 or MDO when it comes to soot or coke?
• Dr. Ram Vis
  Viswa Lab Corp.
  

  

  
  GMT 23:57
  18th Nov 2007
  IP: x.x.75.60

  "Soot is made of very small particles which appear in smoke as a result of incomplete combustion. Soot is produced in the gas phase (distilled and pyrolized components from the fuel droplets).
  
  Coke and Cenosphere are the remanents of the distillation of a droplet of fuel oil. There is first a distillation of the lighter fractions, while the heavy fractions tend to transform themselves into coke, forming a shell around the droplet. Large droplets give large Coke spheres or Cenospheres.
  
  Since there is a heavy dependence of the droplet size, it will be different for slow and medium speed engines. There is a correlation between excess air and amount of Soot in the exhaust. To reduce Soot, excess air has to be increased. Heavier fuel are prone to Soot formation because of higher ratio of Carbon to Hydrogen in their molecular structure. Heavier fuel oils will contain larger amounts of unsaturated molecules."