Transcript 10 - BHEL PSWR

INSTRUMENTATION
PRESSURE MEASUREMENT:
TWO Nos. PRESSURE TRANSMITTERS PROVIDED IN THE
UPSTREAM OF HP BYPASS PRESSURE CONTROL VALVES, IN
THE MAIN STEAM LINE.
RANGE : 0 TO 200 kg/sq.cm
TEMPERATURE MEASUREMENT:
TWO Nos. K-TYPE DUPLEX THERMOCOUPLES ARE PROVIDED
IN EACH LINE, LOCATED AT THE DOWNSTREAM OF EACH HP
BYPASS PRESSURE CONTROL VALVES.
RANGE : 100 TO 450°C.
PROCESS MONITORING
PRESSURE / TEMPERATURE MEASUREMENT:
The 4 to 20 mA analog signals received from the Pressure
transmitters and the mV signals received from Thermocouples
are digitally processed in the DCS. These signals are monitored
to generate internal and external digital signals for interlocks
and alarm generation.
ALARMS, INTERLOCKS and
PROTECTION
ALARMS:
The following are the main Alarms generated in the system:
• Pressure/Temperature transmitters failure.
• Main steam pressure too high.
• Downstream temperature high/very high.
• Tracking Pressure set point failure.
• Pressure control valves opened more than 2%.
• Pressure control valves closed less than 2%.
• Hydraulic Oil pressure too low.
• Any fast opening criteria operated.
• Any closing criteria operated.
ALARMS, INTERLOCKS and
PROTECTION
INTERLOCKS:
The following are the important interlocks provided in the
system:
• When the Pressure control valves are closed less than 2% and
in Manual mode, a forced close signal is provided to prevent
the valve from drift open.
• When the Main steam pressure is too high, then the Fast
opening device is activated.
• Whenever the pressure control valve is opened more than
2%, then the associated Spray control valve will switchover
to Auto mode, if it was in Manual mode before.
• When the system is in auto mode and if the process signal is
failed, then the associated control loop will be switched to
manual mode.
ALARMS, INTERLOCKS and
PROTECTION
PROTECTION:
The following are the important interlocks provided in the
system:
• When the down stream temperature of Pressure control valves
is too high or when the condenser vacuum is low, then the
Pressure control valves are closed on priority.
• When the Turbine trips or when the Generator CB is open,
the opening device is activated to prevent Boiler trip.
HP / LP BYPASS SYSTEM
HRH
MSL
BP
BOILER
HPT
LPT
MPT
CRH NRV
CRH
LBP
LPC
CO
N
BPE
LBP
E
BD
BFP
LEGEND
BP : HP BYPASS VALVE
LBP: LP BYPASS VALVE
BFP: BOILER FEED PUMP
HPT: HIGH PRESSURE TURBINE
MSL: MAIN STEAM LINE
BD :
BPE :
CRH :
HRH :
MPT :
HP SPRAY ISOLATION VALVE
HP SPRAY VALVE
COLD REHEAT LINE
HOT REHEAT LINE
MEDIUM PR. TURBINE
CON : CONDENSOR
LBPE : LP SPRAY VALVE
LPC : LP COOLER
LPT : LOW PR. TURBINE
HP BYPASS CONTROL SCHEME
MAIN STEAM LINE
To TURBINE
P
=
BD
TEMPERATURE
SET POINT
STATION
MASTER
PRESSURE
CONTROLLER
PRESSURE
SET POINT
STATION
BPE
=
T
To CRH
TEMPERATURE
CONTROLLER
Reheater Protection Logic