To achieve this, the design of thrust bearing permits axial displacement when a hydraulic system supplies fluid to corresponding cylinders; axial stops limit rotor displacement in in the
Trang 1DRAWING/DOCUMENT STATUS FOR REFERENCE
PROJECT :
CAMAU 1 750MW COMBINED CYCLE POWER PLANT
PETRO VIETNAM CPMB
s
DRAWING TITLE :
System Description Hydraulic Clearance Optimization
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 Hydraulic Clearance Optimization
Zähl.-Nr
Reg.-No 355062 Dienstst./Dept UNID Index/Rev Version
Blatt-Nr./Page-No
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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
Gas Turbine Instrumentation 3.1-1000
P+I Diagram Gas Turbine 3.1-1010
P+I Diagram, Hydraulic
Clearance Optimization 3.1-1510
Lube and Jacking Oil System 3.1-8000
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
An efficiency improvement and output increase can be
achieved if the GT rotor is shifted against the direction of
flow This reduces clearances between the turbine blades
and casing, in the compressor the corresponding
clearances are increased By virtue of the gas turbine’s
mechanical design the losses in the compressor caused by
this are lower than the improvements in the turbine
This shifting operation may only be performed when the
GT has thoroughly warmed up To achieve this, the design
of thrust bearing permits axial displacement when a
hydraulic system supplies fluid to corresponding cylinders;
axial stops limit rotor displacement in in the primary
displacement direction and in the secondary displacement
direction
The operating pressure of max 180bar is generated by
a separate hydraulic supply system Axial displacement
must be performed slowly to prevent excessive mechanical
loadings on the structural elements of the bearing Defined
displacement times can only be achieved when the
hydraulic system is vented, for this reason the system must
be completely filled with hydraulic fluid (lube oil) the thrust
bearing for each displacement direction is provided with a
supply and a return line To keep pump loadings at low
levels and prevent rapid fouling of the filter, the return line
is shut off so that oil cannot continuously ciruculate in the
hydraulic clearance optimization (HCO) system
To permit replacement of hydraulic fluid and prevent
excessive warming, a flushing operation is performed
during operation of the GT to regularly replace hydraulic
fluid in the HCO thrust bearing that is activated at that time
This also displaces any trapped air bubbles or solid
contamination caused by abrasion of the HCO piston seals
Furthermore, the flushing operation constitutes a function test of the bladder accumulator and instrumentation
Configuration
The HCO supply unit comprises a base frame on which two 100% pumps, a hydraulic bladder accumulator, and the HCO control block and associated instrumentation are mounted The operating medium is lube oil taken from the supply line of the lube oil system Lube oil is returned from this hydraulic system to the lube oil tank
To achieve the requisite operating pressure on the order of 160 to 180bar, two gear pumps (MBA51AP001/002) are provided that are driven by AC motors; these pumps are protected by a safety valve (MBA51AA191) Other than during the pump test which is performed once when the HCO system is started up, only one pump is intermittently in operation to charge the bladder accumulator MBA51BP001 A given pump can be selected via the I&C system Changeover to the other pump is made in the event of a fault to the pump that is selected Each of these pumps is capable of maintaining the operating pressure in the event of a loss of accumulator function or failure of the HCO piston chamber return line shutoff element
To perform the principal task of permanently supplying oil to the primary and secondary piston chambers of the HCO thrust bearing, a bladder accumulator with corresponding accumulator safety block MBA51AA193 is provided on the HCO supply station This accumulator is charged by the above-mentioned pumps and can be isolated from the system using shutoff valve MBA51AA255 and relieved via drain valve MBA51AA257
A manually-actuated shutoff valve (MBA51AA251 and MBA51AA252, respectively) is provided upstream of each pump to permit inspection and maintenance work Each of these vavles is equipped with a position limit switch for monitoring the valve setting OPEN These pumps shall only be started up when the corresponding valve is open
To protect the flow control valves, oil is cleaned by filter MBA51AT001 located downstream of the pumps Filter fouling is monitored by differential pressure switch MBA51CP003 A pretrip alarm is annunciated if response
of this switch persists for longer than 5 seconds
2/2-way solenoid-type seat valves (MBA53AA001 to .006) are provided in the supply and return lines of the primary and secondary displacement directions to enable pressurizing and relieving of the primary and secondary displacement direction pistons The following flow control valves are installed to ensure that the permissible axial shaft displacement times are achieved: MBA53AA152 and MBA53AA153 downstream of the solenoid valves in the
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supply line to the respective HCO piston chamber and
MBA54AA154 and MBA54AA155 upstream of the solenoid
valves in the return lines Both the solenoid valves and the
control valves are located in a single overall control block
mounted on the supply station Pressure limiting valves
MBA54AA151 and MBA54AA152 are provided to guard
against impermissible pressure increases in the piston
chambers of the HCO bearing; in the event of a fault these
valves route oil directly into the lube oil tank
The overall control block also includes the pressure
limiting valve (MBV53AA154) and the associated shutoff
valve (MBV53AA251), which are used during initial filling of
the system
Pressure transducers MBA51CP101 und MBA51CP102
are used to register HCO system pressure in the common
line upstream of the solenoid valves In the interest of
availability, these are redundant Pressure gauge
MBA51CP501 is provided for checking system pressure
locally
Pressure transducers MBA53CP101/102 are located in
the return line from the primary displacement piston
chamber and MBA53CP103/104 in the return line from the secondary displacement piston chamber These pressure sensors can be used to monitor pressure in the respective piston chambers In the interest of availability, these pressure sensors are redundant
A sight glass (MBA51CF501) is installed in the common return line of the HCO supply station that leads to the tank
Position Transducers
Two analog position transducers (MBA10CG101/102) are installed on the compressor bearing cover These transducders permit detection of the (axial) rotor shaft position and measurement of the displacement of the shaft caused by the HCO system In the interest of availability, redundant transducers are provided These position transducers are not depicted in the P+ID of the hydraulic clearance optimization system supply station
1 Sub-distribution
2 Pressure transducer Pressure gauge
3 Base frame
4 HCO control block
5 Bladder accumulator
Fig 1 + 2: HCO supply unit comprises
6 Motor and pump
7 Pressure transducer