If the primary pump should fail, the standby pump will automatically start to ensure a continuous supply of hydraulic fluid.. Loss of operating pump discharge pressure, detected by the p
Trang 1DRAWING/DOCUMENT STATUS FOR REFERENCE
PROJECT :
CAMAU 1 750MW COMBINED CYCLE POWER PLANT
PETRO VIETNAM CPMB
s
DRAWING TITLE :
System Description Hydraulic 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 Hydraulic Oil System
Zähl.-Nr
Reg.-No 355023
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
Specification for Hydraulic Oils 3.1-0251
P+I Diagram, Hydraulic System 3.1-9010
Settings, limits and measuring ranges of the items of
equipment listed here are given in the List of Measuring
Instruments, the Equipment List and the List of Control
Settings (SREL) This description only gives guideline
values
General System Description
The hydraulic supply system provides pressurized
hydraulic fluid for operation of the control actuators in the
auxiliary equipment System components are mounted on
the hydraulic power unit (HPU)
Hydraulic fluid is contained in a reservoir, which is
equipped with instrumentation for status and protective
functions Fluid is pumped from the reservoir by one of two
redundant pumps
If the primary pump should fail, the standby pump will
automatically start to ensure a continuous supply of
hydraulic fluid
Instruments are located on the skid for local monitoring
of system status
Hydraulic fluid cleanliness is required for long-term
system reliability The cleanliness, in accordance with ISO
Standard 4406, shall be: 17/15/12 Therefore, the system
includes continuous in-line filtration of the supply fluid as
well as the main filtering in the conditioning loop
Fluid shall be replaced every two to three years to maintain
proper lubricant additive levels The volume of the tank is
approximately 400 liters (105 Gal) New oil shall be filled in
through the filling valve, MBX06AA252 New oil does not
normally fulfill the cleanliness requirements Therefore, the
oil shall be circulated through the conditioning loop for a
minimum of four hours after filling Valves,
MBX03AA251 / MBX03AA253, shall be closed during that
procedure
Fluid Reservoir
The fluid reservoir, MBX01BB001, is a steel vessel
equipped with measuring instruments
A level switch, MBX01CL001, is used for remote
indication of the level A thermometer, MBX01CT501, and
double resistance temperature device (RTD),
MBX01CT101, provide local and remote indication of the reservoir fluid temperature
The reservoir is equipped with a descant air filter, to minimize moisture into Hydraulic reservoir
Hydraulic Supply Pumps
Two AC motor-driven variable displacement pressure-compensated pumps, MBX02AP001 / MBX02AP002, are mounted on top of the hydraulic fluid reservoir Each pump
is capable of supplying the total requirements of the system One pump is normally operating with the other acting as a standby The operating pump can be pre-selected The adjustable relief valves, MBX02AA191/ MBX02AA193, control the pumps so that the displacement
of the operating pump is automatically varied to meet the system demand These valves ensure a constant discharge pressure of 160 bar (2320 psi) Loss of operating pump discharge pressure, detected by the pressure transmitter MBX03CP101, will automatically start the standby pump The discharge lines of the two pumps merge downstream of the supply line filters A check valve, MBX03AA201 / MBX03AA202, is located at the discharge
of each pump to prevent backflow through the standby pump
Pressure gauges, MBX02CP501 / MBX02CP502, provide local indication of pump discharge pressures Pressure relief valves, MBX02AA192 / MBX02AA194, adjusted at 180 bar (2610 psi), are installed downstream of the pumps to prevent impermissibly high pressures within the hydraulic system
A check valve is located at the discharge of each pump
to prevent backflow through the standby pump
Conditioning loop
Each variable displacement pump has a coupled gear pump that continuously circulates hydraulic fluid through the conditioning loop, that means from the reservoir, through the oil-air cooler, MBX06AH001, then through the main filter and back to the reservoir This ensures the required cleanliness and temperature range
The fan of the cooler provides airflow that cools the hydraulic oil inside the finned tubes Operation of the fan is thermostatically controlled by resistance thermometer MBX01CT101, which senses reservoir oil temperature A cooler bypass valve is used to prevent any potential cooler over-pressurization
The main filtering is performed in the conditioning loop
by filter MBX06AT003; the filter element is designed to meet a 3 µm (3 micron) absolute rating Oil, which enters the reservoir, passes that filter (re-circulating oil, returning
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oil and oil which is filled in through valve MBX06AA252)
This reliably ensures that no debris enters the system
Filter differential pressure is monitored by
MBX06CP002
The conditioning loop may be isolated by closing valve
MBX06AA251 Oil then flows directly back into the tank
through the check valves, MBX06AA191 / MBX06AA192,
which function as pressure relief valves and limit the gear
pump discharge pressures This isolation of flow is required
prior to performing filter element replacement
Supply Filters
The discharge pipe of each pump is equipped with
supply line filter MBX03AT001 / MBX03AT002 Filter
elements have a 10 µm (10 micron) absolute rating
Pressure differential switches, MBX03CP0001/
MBX03CP002, provide remote and local indications for
visual observation of filter cleanliness status Since the
supply line filters are intended to function simply as a
protective device, they are subjected to little fouling during
service If the set point of at least one of the two differential
pressure switches is exceeded for more than 10 minutes,
the pre-trip alarm "Hydraulic oil filter fouled" is indicated
When one filter element is being changed, the other
pump has to assume the task of supplying hydraulic oil
Valves MBX03AA251and MBX03AA252 or MBX03AA253
and MBX03AA254 can individually isolate the filters
Accumulators
Two bladder accumulators, MBX04BB001/
MBX04BB002, are connected to the discharge downstream
of the supply filters The accumulators are charged with
nitrogen to a pressure of 100 bar (1450 psi)
Each hydraulic oil accumulator is provided with a
pressure gauge, MBX04CP501 / MBX04CP502, a shutoff
valve, MBX04AA251 / MBX04AA252, drain valve,
MBX04AA401 / MBX04AA402, and safety valve,
MBX04AA191 / MBX04AA192, respectively
The design of the accumulators assumes rapid and
sudden controlled positioning of the actuators, concurrent
with the failure of the operating pump and an initiated pump
changeover from operating pump to standby pump
Pressure Monitoring
Pressure transmitter, MBX03CP101, monitors hydraulic
power unit discharge pressure directed to the system
Dependent of the signals of the pressure transmitter:
− The standby pump is switched on during the start-up of
the GT, in addition to the operating pump
− The standby pump is additionally switched on if the pressure drops below the lower value of pressure threshold P.Hyd.02, e g 145 bar (2103 psi )
− During operation the standby pump can be switched off manually after reaching the upper value of pressure threshold P.Hyd.02, e g 150 bar (2175 psi)
− High pressure is indicated, if pressure exceeds threshold P.Hyd.05, e.g 170 bar (2465 psi)
Pressure gauge, MBX03CP501, senses and displays hydraulic power unit discharge pressure to the system Pressure gauge, MBX06CP501, is located upstream of the air-cooled heat exchanger and gives a local indication
of loop pressure
Temperature Monitoring
For optimum operation of the hydraulic actuators it is necessary to keep the oil within the optimum viscosity range The viscosity depends on the oil and on the temperature Therefore, the oil is to be heated or cooled according to requirements During operation, only cooling
is necessary, which is realized by the air-oil-cooler During standstill, the oil is heated by operation of one pump, if the temperature falls below a certain threshold The signal of the RTD is used for:
− Activating heating via pumps during standstill when temperature falls below threshold T.HYD.01, e.g 20 °C
− Deactivating heating via pumps during standstill when temperature exceeds threshold T.HYD.02, e.g 25 °C
− Switching the cooler on when temperature exceeds threshold T.HYD.04, e.g 55 °C
− Switching the cooler off when temperature falls below threshold T.HYD.03, e.g 45 °C
− Indicating high temperature at threshold T.HYD.05, e.g
70 °C
− Indicating low temperature at threshold T.HYD.06, e.g
10 °C
Level Monitoring
Switching point MBX01CL001-S01 indicates low; switching points MBX01CL001-S02 and MBX01CL001– S03 indicate too low level A level gauge, MBX01CL501, provides local indication of the level If the oil level in the tank drops below at least two of the limits, MBX01CL001-S01, MBX01CL001-S02 or MBX01CL001-S03 (2-of-3 logic), a trip is initiated