Adjustable orifices MBV22AA281 in the cooler bypass line and MBV24AA281 downstream of the point where the bypass line joins the main supply line permit adjustment and precise control of
Trang 1DRAWING/DOCUMENT STATUS FOR REFERENCE
PROJECT :
CAMAU 1 750MW COMBINED CYCLE POWER PLANT
PETRO VIETNAM CPMB
s
DRAWING TITLE :
System Description Lube and Jacking Oil System
Ursprung/Original Ursprung-Nr./Original-No Urspr.-PKZ-Nr Orig.-PC
Datum
Date
Name Maßstab
Scale N/A A4 UA/DCC Type XS00
gezeich
Drawn 06-04-10 STEENM Benennung/Title
Inhaltskennzeichen Contents Code bearb
Coord 06-04-10 LIEDTKE
geprüft
Abtlg
Dept P415 sgd
System Description Lube and Jacking Oil System
Zähl.-Nr
Reg.-No 355022
Dienstst./Dept UNID Index/Rev Version
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Refer also to:
List of Control Settings (SREL) 3.1-0210
List of Measuring Instruments 3.1-0220
List of Electrical Loads 3.1-0230
Equipment List 3.1-0240
P+I Diagram, Lube and Jacking Oil 3.1-8010
Settings, limits, and measuring ranges of the devices
referred to here are given in the List of Measuring
Instruments, Equipment List, and List of Control Settings
(SREL) This description only gives guideline values
Function
The lube oil system supplies oil to the compressor
bearing MBD12 and the turbine bearing MBD11 of the gas
turbine, as well as to the generator bearings MKD11 and
MKD12 In doing so, the lube oil supply system performs
several tasks: on the one hand it forms an oil film in the
bearings that separates the rotating shafts from the bearing
shells and thus minimizes friction, on the other hand the
flow of lube oil removes heat from the bearings In addition,
any wear debris or solid contaminants contained in the oil
are flushed out of the bearings and removed by filtration at
another location in the lube oil system
Oil Tank
Oil tank MBV10BB001 functions both as a collecting
and supply tank as well as a deaerator for the lube and
jacking oil This tank is provided with a filler opening and
drain valve MBV10AA401 The oil level can be read off at
sight glass MBV10CL501 and is continuously monitored by
level monitor MBV10CL001 In the event that the tank oil
level declines below a certain limit
(MBV10CL001-S01 <Min), a pretrip alarm is annunciated A pretrip alarm
is also annunciated if the oil tank level exceeds a certain
value (MBV10CL001-S03 >max) If the oil level continues
to rise and level switch MBV10CL001-S04 signals level
>>Max, trip is triggered and the startup interlock prevents
the gas turbine from being restarted This level can only be
reached if a leak in the lube oil cooler allows water to flow
into the lube oil system If the oil level in the tank declines
below the setpoint of level switch
MBV10CL001-S02 <<Min, for example, due to a leak, GT trip is triggered,
the main and auxiliary lube oil pumps are shut down and
the emergency oil pump is started up Response of the fire
protection system triggers shutdown of the main and
auxiliary lube oil pumps as well as the jacking oil pump and
starts up the emergency oil pump, which has a lower
capacity If this occurs, the gas turbine automatically trips
and is shut down An interlock prevents restarting the gas turbine in such cases
An oil vapor extractor is mounted on the lube oil tank It extracts oil vapor from the tank, at the same time producing
a slightly subatmospheric pressure in the tank and the return lines of the entire lube oil system As the return lines are not completely filled, a subatmospheric pressure prevails in the entire return piping system as well as in the bearing housings of the GT and generator This subatmospheric pressure prevents the escape of oil vapor
or oil from shaft penetrations and other seals It also promotes degassing of the oil in the lube oil tank Extraction is redundant and employs the two side channel compressors MBV50AN001 and MBV50AN002 If the on-line fan sustains an outage, a fault alarm is issued and the standby fan started up Oil vapor is fed first to oil separator MBV50AT001 to prevent the escape of any oil to the surroundings Swing check valves MBV50AA201 and MBV50AA202 prevent circulation and the ingress of ambient air into the system when the respective fan is not running Pressure transducer MBV50CP101 monitors the subatmospheric pressure in the lube oil tank and this pressure is indicated locally on pressure gauge MBV50CP501 To set the requisite subatmospheric pressure, a side stream flow of air can be admixed to the extracted flow via valve MBV50AA283 and filter MBV50AT002 Pressure is displayed locally by gauges MBV50CP502 and MBV50CP503 that indicate pressure upstream and downstream of the separator and by pressure gauge MBV50CP501 that indicates the tank pressure To set the requisite subatmospheric pressure, a side stream flow of air can be admixed to the extracted flow via valve MBV50AA283 and filter MBV50AT002
Lube Oil Pumps
Several pumps are provided to boost the pressure of lube oil to the level required for supplying the bearings The main lube oil pump MBV21AP001 supplies the bearings with oil during normal operation Other pumps include the auxiliary lube oil pump MBV21AP002, of a design identical
to that of the main lube oil pump, and the somewhat smaller emergency lube oil pump MBV21AP003 All of these pumps are vertical-shaft, single-stage centrifugal pumps The emergency lube oil pump is driven by a DC motor The main and auxiliary lube oil pumps are equipped with three-phase drive motors Swing check valves MBV21AA201, MBV21AA202, and MBV21AA203 are provided downstream of the respective pumps to prevent loop reverse flow circulation of oil through any pump that is shut down
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Lube Oil Cooler
Cooler MBV23AH001 is located in the lube oil supply
line (some configurations include more than one cooler)
Control valve MBV24AA151 is used to control lube oil
temperature by adjusting the fraction of lube oil which is fed
through the cooler bypass line Temperature control valve
lift is varied as a function of the oil temperature in the
supply line downstream of the cooler Adjustable orifices
MBV22AA281 in the cooler bypass line and MBV24AA281
downstream of the point where the bypass line joins the
main supply line permit adjustment and precise control of
the lube oil mass flow supplied to the bearings
Lube Oil Filters
The flow of cooled lube oil is fed through filter
MBV25AT001 or MBV25AT002 Pressure drop across the
filter is monitored by differential pressure switch
MBV25CP001 If the pressure drop exceeds the setpoint of
the differential pressure switch the pretrip alarm “Lube oil
filter fouled” is annunciated In this case the clean standby
filter must be filled with oil by opening valve MBV25AA252
Then the flow must be switched over to the clean filter with
valve MBV25AA251 and the fouled filter replaced Shutoff
valves MBV25AA401 and MBV25AA402 are used to drain
the respective filter chamber
Swing check valve MBV25AA201 is located
downstream of the duplex filter and upstream of the
connection of the emergency oil pump discharge line to the
main supply line This swing check valve prevents lube oil
from being pumped in the reverse direction through the
duplex filter and main or auxiliary pump into the tank during
operation of the emergency oil pump
Lube Oil Pressure Monitoring
The function of the main and auxiliary lube oil pumps is
monitored by the lube oil pressure switch MBV21CP001
and indicated on local pressure gauge MBV21CP501
Bearing oil supply pressure is monitored by pressure
switches MBV26CP002 and MBV26CP003 as well as
pressure transducer MBV26CP101 Pressure switch
MBV26CP003 directly activates the supply of DC power to
the emergency lube oil pump and thus enables startup of
this pump even in the event of an I&C failure Pressure
gauge MBV26CP501 is provided to permit visually
checking bearing oil supply pressure
The auxiliary oil pump and emergency oil pump are
started concurrently and without delay if lube oil pump
pressure declines below the setting of pressure switch
MBV21CP001 (for example, 4.5bar), or if the lube oil
of the discharge line from the emergency oil pump to the lube oil supply line by pressure transducer MBV26CP101 declines below limit P.SCHMOEL.01 (for example, 1.5bar)
It is permissible to manually shut down the emergency lube oil pump once it has been ascertained that the auxiliary lube oil pump has assumed lube oil supply functions
The emergency oil pump is started immediately if lube oil pressure declines below the setting of pressure switch MBV26CP002 (for example, 1.0bar) or MBV26CP003 (for example, 1.0bar)
Gas turbine trip is triggered if at least two of the following three signals are issued:
− Lube oil pressure declines below the setting of pressure switch MBV21CP001 (for example, 4.5bar),
− Bearing oil supply pressure, measured by pressure transducer MBV26CP101, declines below limit P.SCHMOEL.01 (for example, 1.5bar) for longer than K.SCHMOEL.05 (for example, 3s),
− Lube oil supply pressure declines below the setting of pressure switch MBV26CP002 (for example, 1.0bar) for longer than K.SCHMOEL.05 (for example, 3s)
Bearing Oil Temperature Monitoring
Temperature transducer MBV26CT101 is provided to monitor the lube oil supply temperature If temperature exceeds T.SCHMOEL.04, the pretrip alarm “Lube oil temperature high” is issued This indicates malfunction of the cooler or the temperature control valve
Oil Lines to and from the Bearings
Lube oil is fed to the bearings via orifices MBV26BP011
to MBV26BP015 Lube oil is fed from the bearings back to the lube oil tank via return lines Sight glasses MBV90-CF501, MBV90CF502, MBV90CF504, and MBV90CF505 can be used to check the return flow of bearing oil
Bearing metal temperature is measured directly and monitored to protect the bearings (see also description 3.1-1000) This direct method of measuring bearing temperature has the advantage of rapidly detecting excessive thermal stresses on the bearings It is thus not necessary to measure and monitor the temperature of lube oil in the return line Excessive heat input into the bearings would also be detected later by measurement of return line oil temperature than by measurement of bearing metal temperature
Lube Oil Heating during Standstills
Lube oil temperature is measured in the tank by
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displayed locally by the instrument MBV10CT501 Heating
the lube oil is achieved by switching on the main and
auxiliary oil pumps when the temperature in the oil tank
declines below temperature T.SCHMOEL.02 (for example,
15°C) These pumps are shut down when the temperature
exceeds T.SCHMOEL.03 (for example, 20°C) Circulation
transfers the thermal losses of the pumps to the oil, thus
not only heating the oil in the tank, but also the lines and
bearing housings This means of heating lube oil is
advantageous as it
− Does not require any additional heating and monitoring
equipment,
− Offers a certain redundancy in that two oil pumps are in
operation,
− Ensures uniform warming of the lube oil and the items
through which it flows
A pretrip alarm is issued if the oil temperature drops
below T.SCHMOEL.01 (e.g., 10°C) If both sensors of
temperature measuring transducer MBV10CT101 indicate
that oil temperature has declined below the setting
T.SCHMOEL.01, startup of the gas turbine is prevented
Jacking Oil System
At low turbine speeds, lube oil alone does not form an
adequate hydrodynamic lubricating film To prevent mixed
lubrication, jacking oil at high pressure is forced into
pockets in the bearing shells below the shaft journals The
shaft is lifted and floats hydrostatically on a film of oil
Jacking oil pump MBV30AP001 draws lube oil from the
oil tank and boosts its pressure to about 140bar The
jacking oil pump is a vane pump driven by a three-phase
electric motor It draws oil directly from the lube oil tank
Swing check valve MBV30AA201 is located below the oil
level to prevent the suction nozzle from running dry In
addition, the suction nozzle is filled from the supply line via
ball valve MBV21AA404, which is open during operation,
and via orifice MBV21BP003, which is permanently open
The suction nozzle is permanently vented via orifice
MBV21BP004 Safety valve MBV30AA191 limits the
pressure downstream of the jacking oil pump to the
permissible level in the event of a pressure control valve
fault or a clogged filter Any dirt present in the oil is
removed by jacking oil filter MBV30AT001 Differential
pressure switch MBV30CP002 signals fouling of this filter
Pressure switch MBV30CP001 is located downstream of
the filter Jacking oil pressure can also be read off display
MBV30CP502, which is mounted on this pressure switch
An alarm is annunciated if jacking oil pressure declines
below the setting of pressure switch MBV30CP001
Pressure control valve MBV31AA151 is located in the jacking oil control block This valve reduces jacking oil pressure to the level required for operation In addition to that for the pressure limiting valve, the jacking oil control block also has connections for distributing jacking oil to the turbine, compressor, and generator bearings Adjustable flow restrictors MBV31AA281 and MBV31AA282 can be used to regulate the flow of oil fed to the respective bearings Swing check valves MBV31AA201 and MBV31AA202 prevent lube oil from draining out of the jacking oil pockets in the bearing shells when the jacking oil pump is shut down, thereby preventing a decline in the hydrodynamic journal pressure Adjustable flow restrictors and swing check valves are also provided at the generator bearings Pressure prevailing in the jacking oil pockets can
be read off pressure instrument displays MBV31CP501 (turbine bearing) and MBV31CP502 (compressor bearing) The jacking oil pump is automatically started up at turbine speeds below S.TURB.12 (for example, 500rpm) and shut down when speed exceeds S.TURB.12
Shaft Turning Gear
After the turbine-generator has been shut down, the line of shafting (gas turbine and generator) is rotated at low speed (for example, 120rpm) in turning gear mode This flow of air forced through the gas turbine ensures uniform cooling of the machine Distortion of the rotor and casing (arching: caused by passive cooling without sufficient air flow through the machine, involves more rapid cooling of the lower casing regions) are prevented, shaft rotation remains unrestricted and the turbine-generator is ready for the next start
The gas turbine remains in turning gear mode until a defined time has elapsed (K.TURN.01 + K.TURN.04, for example, 24 hours), allowing the machine to sufficiently cool down This phase is also known as cooldown turning The turning gear is shut down after conclusion of cooldown turning When the shaft has come to a standstill (speed lower than S.TURB.02 (for example, 6rpm) for longer than K.SCHMOEL.08 (for example, 10min)), the jacking oil pump and the lube oil pump are shut down
The shaft is turned briefly at regular intervals of K.TURN.02 (for example, every 6 hours) during extended outages to confirm that it still turns freely Turning speed is not reached at such times This operation is known as interval turning
The gas turbine is started either from a standstill or with the shaft coasting down If running, the turning gear is shut down prior to starting the gas turbine
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Turning speed is selected so as to ensure sufficient air
throughput for uniform cooling of the casing and to prevent
blade clattering
For mechanical design reasons the turbine blades are
seated loosely in the rotor disk slots at room temperature
At very low shaft speeds the blade roots shift slightly in
their slots and clatter audibly Above a certain speed
centrifugal force firmly seats the blade roots
The shaft turning gear is located in the compressor
bearing region It comprises hydraulic motor MBK22AE001
connected to a drive pinion The drive pinion is
permanently meshed with a second pinion mounted on the
free end of a swingarm Hydraulic cylinder actuator
MBK21AU001 pivots the swingarm inward to mesh the
pinion at the latter’s free end with a gear ring mounted on
the intermediate shaft that connects the gas turbine to the
generator Spring force returns the swingarm to its
disengaged position The speed of the hydraulic motor is
measured by speed sensors MBK22CS101 and
MBK22CS102 The speed of the hydraulic motor is
matched to that of the GT shaft after allowing for the gear
ratio of the drive pinion and gear ring
Jacking oil is supplied to the hydraulic motor and the
swingarm actuator During operation of the gas turbine with
the jacking oil pump shut down, the hydraulic motor is
supplied with lube oil via swing check valve MBV35AA201
to prevent damage that is typical of extended equipment
standstills
When solenoid valves MBV35AA001 and
MBV35AA002 of the swingarm actuator are energized,
pressurized oil is supplied to hydraulic cylinder
MBK21AU001 and the swingarm pivots inward, meshing
the pinion at its free end with the gear ring Swingarm pivot
speed can be adjusted by actuating flow control valve
MBV35AA151 located downstream of the solenoid-type
valves of the swingarm actuator Pivoting the swingarm to
engage and disengage should be performed quickly and as
smoothly as possible (engaging time of 1s, for example) If
the solenoid valves of the swingarm actuator are
deenergized or if the jacking oil pressure declines, the
swingarm is returned to its disengaged position by spring
force
The hydraulic motor is supplied with jacking oil via solenoid-type shutoff valve MBV35AA003 and flow control valve MBV35AA101 The speed of the hydraulic motor is varied between standstill (speed 0rps) and turning speed
by adjusting the lift of flow control valve MBV35AA101 Two mechanical stops are used to set turning speed During the transition from power operation to cooldown turning, the pinion gear on the swingarm is generally engaged when turning speed is reached during coastdown, connecting the shaft of the hydraulic motor with that of the turbine-generator
Solenoid valves Y01 and MBV35AA101-Y02 are used to control the speed of the hydraulic motor (greater oil flow = higher speed and vice versa)
The turning gear can be engaged while the turbine-generator shaft is at rest or coasting down When the turbine-generator shaft is at rest, the swingarm is pivoted inward to engage the pinion gear mounted on its free end with the gear ring on the turbine-generator shaft; this is performed with the hydraulic motor shut down (type shutoff valve MBV35AA003 is closed) The solenoid-type shutoff valve is then opened and the actuator of the flow control valve is actuated using a time function to achieve the lift required for turning speed This begins turning gear operation
If turbine-generator speed drops below engaging or turning speed during coastdown without engaging having occurred (e.g., failed start), solenoid valves MBV35AA101-Y01 and MBV35AA101-Y02 can be used to match the engaging speed of the hydraulic motor to that of the shaft When the GT shaft speed equals (is synchronous with) that
of the hydraulic motor, the solenoid valves of the swingarm actuator are energized and the swingarm is pivoted inward
to its engaged position With the swingarm in its engaged position the flow control valve is actuated using a time function to achieve the lift required for turning speed This begins turning gear operation
Turning gear operation is terminated by closing the solenoid valves of the swingarm actuator and the solenoid-type shutoff valve This causes the swingarm to pivot outward to its disengaged position and the hydraulic motor coasts to a stop