IHI NIIGATA MG(L)26HLX, Инструкция по эксплуатации

Страница: 85 / 204

This document is property of NIIGATA POWER SYSTEMS CO., LTD. It must be neither reproduced nor communicated nor published without permission.
SECTION
２
- OPERATING INSTRUCTION
2.9 CARE OF LOW LOAD OPERATION
２－９－０１
2.9 CARE OF LOW LOAD OPERATION
In supercharged engines for improvement of thermal efficiency, valve overlap,
which means the timing both exhaust and intake valves are opening, is prepared.
But in low load operation, the supercharger does not work fully for too few
exhaust gas. The change air pressure, is lower than the exhaust gas pressure.
so the exhaust gas turns back to the combustion chamber.
Therefore imperfect combustion increases and carbon depositsin a combustion
chamber. Otherwise combustion pressure is useful for oil control of piston rings.
The liner contact pressure is increased by the back pressure of rings.
But in low load operation, this function does not work usefully, so oil rises to
the combustion chamber. This carbon deposits also in the chamber.
These deposit tend to occur ring stick or piston scuffing Therefore the load rate
of diesel engine with supercharger should be more than 30%, and after
operating at no load or low load, you should to operated at more than 50% load
for removing the carbon deposit by high temperature and high gas volume.
For the engines operated continuously, air heater cooler or central cooling or
etc. are considered for improvement of low load combustion.
But for the emergency, the combustion improvement is scarcely considered on
the situation. so,it is the most important that the maintenance and inspection
are carried out following the schedule.