Cleaning Turbine And Nozzle Ring During Operation - ABB PT004161 Operation Manual

Operation Manual / Power2 845-M / High-pressure stage
7 Periodic maintenance / 7.3 Cleaning turbine and nozzle ring during
operation
7.3

Cleaning turbine and nozzle ring during operation

7.3.1 Introduction
Approval by enginebuilder
The following instructions for wet cleaning only apply to cleaning with pure water and under
the precondition that the enginebuilder approves the process.
General
The combustion of fuels such as marine diesel oil (MDO) and heavy fuel oil (HFO) in diesel
engines causes contamination of the turbine components of the low and high-pressure
stages. Poor quality fuel in conjunction with a high exhaust gas temperature can lead to very
hard deposits on the nozzle ring, the turbine blades and particularly on the casing walls sur-
rounding the impellers.
The formation of deposits on the turbine components stems from the following combustion
products:
¡
Soot
¡
Molten ash
¡
Cinders
¡
Incompletely burnt fuel
¡ Sodium vanadyl vanadate
It is advantageous to use fuels with low ash, sulphur, sodium and vanadium contents. The
fuel must also be correctly stored, prepared and handled.
Turbo Systems recommends using fuels with a mass ratio of vanadium to sodium of less
than 3:1 so that the melting temperature of the sodium vanadyl vanadate is as high as pos-
sible.
Consequences of contamination:
¡
Poor turbine efficiency
¡
Elevated exhaust gas temperatures
¡
Higher charging and ignition pressures with increasing speed of the low and high-pres-
sure stages
¡
Lower engine performance
¡
Increased rotor unbalance
Experience in operation shows that, with periodic cleaning during operation, the interval
between overhauls can be extended. The wet cleaning of a turbine described in the following
can be used for 4-stroke applications with heavy deposits (such as MDO and HFO applica-
tions, for example). Generally, turbine cleaning is not required for the other applications.
Periodic cleaning of the turbines during operation never replaces the service work where the
low and high-pressure stages are completely dismantled and mechanically cleaned.
Very heavily contaminated turbines can no longer be cleaned in this way. In this case, the
contaminated components must be cleaned mechanically by a service station.
© Copyright 2022 ABB. All rights reserved. HZTL4069_EN Rev.F March 2022