Man L23/30DF, Project Manual

Page: 261 / 392

Description
High exhaust gas temperatures are often observed
and claimed in service. High exhaust gas tempera-
tures are normally caused by fouling on the turbine
side of the turbocharger:
➣
Fouling turbine (coke deposit)
➭
Lower turbocharger performance
➭
Lower air flow / pressure through the engine
➭
Increasing exhaust gas temperatures
➭
Increasing fuel oil consumption
Fouling of the turbine and consequently higher
exhaust gas temperature is influenced by: level of
maintenance, condition of the fuel injection noz-
zles / fuel pumps, fuel oil quality and/or long-term
low-load operation.
Smaller turbochargers are, due to area-relation in
matching parts, more sensitive to coke deposit than
larger turbochargers and consequently low power
engines as L16/24 or L23/30H will need turbine
cleaning more frequent than more powerful
engines.
Turbine cleaning intervals must be expected to be
following when operating on HFO:
“D-D” Dry-cleaning Daily Cleaning
“W-W” Wet-cleaning Weekly
Cleaning intervals can be shorter/longer based on
operational experience. Regular performance
observations will show the trend in charge air pres-
sure, exhaust gas temperatures, and define the
cleaning intervals for the turbine. However the tur-
bine must be cleaned when exhaust gas tempera-
ture before turbine are about 20°C above the nor-
mal temperature (ISO corrected) (Sea trial).
Practical service experience have revealed that tur-
bine side of turbocharger only can be sufficient
cleaned by combination of nut-shell dry cleaning
and water washing.
Dry cleaning of turbine side
This cleaning method employs cleaning agents con-
sisting of dry solid bodies in the form of granules. A
certain amount of these granules, depending on the
turbocharger size, is, by means of compressed air,
blown into the exhaust gas line before the gas inlet
casing of the turbocharger.
The injection of granules is done by means of work-
ing air with a pressure of 5-7 bar.
On account of their hardness, particularly suited
blasting agents such as nut-shells, broken or artifi-
cially shaped activated charcoal with a grain size of
1.0 mm to max. 1.5 mm should be used as clean-
ing a gents.
The solid bodies have a mechanical cleaning effect
which removes any deposits on nozzle vanes and
turbine blades.
Dry cleaning can be executed at full engine load
and does not require any subsequent operating
period of the engine in order to dry out the exhaust
system.
MAN Diesel & Turbo
3700418-8.1
Page 1 (6)
Cleaning the turbocharger in service - turbine side
B 16 01 3
L28/32DF, V28/32S, L28/32S, L28/32H, L27/38S, L27/38, L23/30DF, L23/30S,
L23/30H, L21/31S, L21/31, L16/24S, L16/24
2017.01.24