WÄRTSILÄ Vasa R22, Instruction Manual

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temperature resistant lubricants are used for exhaust pipe
screws.
15.1.3 Water cleaning of turbine
During operation, especially when running on heavy fuel, impu-
rities in the exhaust gases sticks to the turbine wheel and other
components in the turbocharger exhaust side. A dirty turbine
causes higher temperatures of the exhaust gas and higher
stresses of the bearings due to imbalance.
Practical experiences show that the deposits on the turbine side
can be reduced by periodic cleaning (washing) during operation
and the overhaul periods can be extended.
During long time of operation, periodic water cleaning prevents
the build-up of significant deposits on the turbine blades and
nozzle blades. This cleaning method does not work on very dirty
turbines which have not been washed regularly.
If the normal water cleaning of the turbine does not have much
effect on the exhaust gas temperature level, hard deposits have
probably been built up on the nozzle ring and the turbine blades
in the turbocharger and they have to be cleaned mechanically.
For that purpose the rotor and the nozzle ring have to be removed
from the turbocharger.
The water must be injected into the exhaust system with the
engine running at reduced output, see 15.1.4. The disadvantages
of reducing the output occasionally is not significant compared
with the advantages of cleaning.
The necessary water flow is basically dependent upon the vol-
ume of gas and its temperature. The flow should be adjusted so
that the major part of the water is evaporated and escapes
through the exhaust. The cleaning effect is based upon the water
solubility of the deposits and the mechanical effect of the striking
water drops. Additives or solvents must not be used in the
cleaning water. The use of salt water is prohibited.
22-200520 Turbocharging and Air Cooling 15
VTR Turbocharger 15 - 3