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INE AXIAL SHIFT MEASUREMENT OF
MAIN OIL PUMP AT THE BBGS UNIT# 3
TURBO GENERATOR SET
SUBHAMAY DAS
CENTRAL TURBINE MAINTENANCE
Abstract
The Steam Turbine Generator assembly is one of the costliest & critical asset of power plants. The rotating part
i.e. the Turbine rotors are rested on bearings. These bearings are lubricated by a bearing lubrication system
which is a very critical system in the power plant.
Main Oil Pump (MOP) is the key equipment of the TG bearing lubrication system. The MOP is connected with
Turbine Rotor train with a flexible coupling such that Turbine rotor expansion cannot move the MOP shaft in
either direction. The MOP impeller is an integral part of the MOP shaft and it is connected with the MOP shaft
separately through longitudinal keys. Both the radial & thrust bearings are housed in the MOP Casing and the MOP
Rotor is rested on these bearings. MOP ‘thrust float’ is a critical parameter in a Turbine Generator unit. During
erection MOP is boxed up keeping design axial float as specified by the OEM. Due to continuous operations, this
‘thrust float’ starts increasing & after a period of operation, it tends to cross the design limit and from that point
onwards probability of failure of the thrust bearing increases. The failure of MOP thrust bearing can further
cause failure of Main Oil pump which in turn will result in lubrication system failure and subsequently cause the
failure of the TG unit. Thus it can cause severe damage to the critical equipment of the power plant as well as
result in major financial losses.
The MOP thrust bearing is inspected as per schedule at the time of overhauling which is generally done within
a span of two years. No online health monitoring is possible during these two years. The intent of this paper
is to leverage adoption of technology to measure real time axial shift of the MOP so that any deviation beyond
threshold can be addressed during any forced unit outage (due to other reasons) or any nearest planned outages
without compromising the reliability of the MOP by waiting till the next major overhauling.
INTRODUCTION BRIEF OVERVIEW OF EXISTING SYSTEM
This Paper describes the installation of Axial shift BBGS Unit#3 is a 250 MW capacity of BHEL make where
probe at MOP casing to monitor the axial shift of the the Main Oil Pump (MOP) of the TG unit is housed at No.
MOP and further to understand the health of MOP 1 bearing pedestal and connected with HP Turbine Rotor
thrust bearing at Unit# 3 of Budge Budge Generating through one extended shaft and flexible coupling. The
Station. Unit was commissioned in the year of 2009. Since then,
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MAIN OIL PUMP AT THE BBGS UNIT# 3
TURBO GENERATOR SET
SUBHAMAY DAS
CENTRAL TURBINE MAINTENANCE
Abstract
The Steam Turbine Generator assembly is one of the costliest & critical asset of power plants. The rotating part
i.e. the Turbine rotors are rested on bearings. These bearings are lubricated by a bearing lubrication system
which is a very critical system in the power plant.
Main Oil Pump (MOP) is the key equipment of the TG bearing lubrication system. The MOP is connected with
Turbine Rotor train with a flexible coupling such that Turbine rotor expansion cannot move the MOP shaft in
either direction. The MOP impeller is an integral part of the MOP shaft and it is connected with the MOP shaft
separately through longitudinal keys. Both the radial & thrust bearings are housed in the MOP Casing and the MOP
Rotor is rested on these bearings. MOP ‘thrust float’ is a critical parameter in a Turbine Generator unit. During
erection MOP is boxed up keeping design axial float as specified by the OEM. Due to continuous operations, this
‘thrust float’ starts increasing & after a period of operation, it tends to cross the design limit and from that point
onwards probability of failure of the thrust bearing increases. The failure of MOP thrust bearing can further
cause failure of Main Oil pump which in turn will result in lubrication system failure and subsequently cause the
failure of the TG unit. Thus it can cause severe damage to the critical equipment of the power plant as well as
result in major financial losses.
The MOP thrust bearing is inspected as per schedule at the time of overhauling which is generally done within
a span of two years. No online health monitoring is possible during these two years. The intent of this paper
is to leverage adoption of technology to measure real time axial shift of the MOP so that any deviation beyond
threshold can be addressed during any forced unit outage (due to other reasons) or any nearest planned outages
without compromising the reliability of the MOP by waiting till the next major overhauling.
INTRODUCTION BRIEF OVERVIEW OF EXISTING SYSTEM
This Paper describes the installation of Axial shift BBGS Unit#3 is a 250 MW capacity of BHEL make where
probe at MOP casing to monitor the axial shift of the the Main Oil Pump (MOP) of the TG unit is housed at No.
MOP and further to understand the health of MOP 1 bearing pedestal and connected with HP Turbine Rotor
thrust bearing at Unit# 3 of Budge Budge Generating through one extended shaft and flexible coupling. The
Station. Unit was commissioned in the year of 2009. Since then,
63
