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Operation Manual / Power2 850-M / High-pressure stage
7 Periodic maintenance / 7.3 Cleaning turbine and nozzle ring during
operation
Draining the gas outlet casing of the low-pressure stage
The following points must be observed with regard to draining the gas outlet casing:
¡
The exhaust gas temperature downstream of the low-pressure stage drops drastically
during cleaning (typical gas outlet temperatures during cleaning: 50 ... 150 °C).
¡
Depending on the engine load, the drainage can take place through the drain pipe. This
drainage may occur after 2 ... 3 minutes or not at all.
¡
If the drainage of the gas outlet casing is omitted, the low-pressure stage speed and/or
the gas inlet temperature must be monitored during the cleaning process. If the load is
too low, water can collect in the gas outlet casing. Indications for this are a sudden
severe drop in the low-pressure stage speed or a very large increase in the gas inlet tem-
perature. In such cases, the cleaning operations must be stopped and the cleaning cycle
restarted with reduced water pressure or higher engine load.
Calculation of the gas pulse
The pulse I
for the flow of gas is calculated according to the following relationship:
G
p
is the density of the exhaust gas at the inlet into the gas inlet casing.
G
V
corresponds to the flow rate at the nozzle ring inlet.
G
A
corresponds to a reference surface of the flow channel at the nozzle ring inlet. The values
NR
are specified in the following table.
Power2
Surface of the flow channel at the
nozzle ring inlet of the HP turbine stage
850
Table 22: Surface of the flow channel
© Copyright 2022 ABB. All rights reserved.
2
[m
]
0.031
HZTL4063_EN
Surface of the flow channel at the
nozzle ring inlet of the LP turbine stage
2
[m
]
0.068
Rev.F
March 2022
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