HP/LP BYPASS SYSTEM
FUNCTION:
TO ENSURE OPERATION OF STEAM GENERATOR BY
MAINTAINING A MINIMUM CIRCULATION OF STEAM FLOW ,
WHEN TURBINE IS NOT IN SERVICE
ADVANTAGES:
*
*
*
QUICK START UP OF THE UNIT
REHEATER PROTECTION DURING START - UP
PARALLEL OPERATION OF STEAM GENERATOR &
TURBINE
*
*
*
HOUSE LOAD OPERATION
LIMITED SAFETY VALVE LIFTING DURING TRIP OUTS
DM WATER SAVING
LIST OF EQUIPMENTS:
1. HP BYPASS VALVE:
ARS100+ASM200-10/SK240
2. HP BYPASS SPRAY VALVE:
3. HP BYPASS ISOLATION VALVE:
E32S+ASM100-10/SK 200
E32S+ASM100-10/SK 200
4. BREAK DOWN ORIFICE
5. OIL SUPPLY UNIT:
0V32B-30-201
6. SERVO VALVE:
ST10-4+R6z
7. SERVO VALVE:
ST10-63+R6z
8. ON-OFF CONTROL UNIT:
APL 6
9. BLOCKING ELEMENT
BL10
10. QUICK OPENING DEVICE
SSB10
11. SS OIL LINES AND HYDRAULIC SYSTEM COMPONENTS
HP BYPASS VALE
1. DESIGN PRESSURE
166.2 KG/CM
2. DESIGN TEMPERTURE
545 C
3. MAX. FLOW
204 T/HR AT 150 KG/Sqcm& 537, C.
4. VALVE TYPE
COMBINED PERSSURE REDUCING
AND DESUPERHEATING VALVES
5. BODY MATERIAL
SA 182 F22 (2 1/4%Cr. 1% Mo STEEL)
6. VALVE SEAT
SA 182 F22 (HARDFACEDWITH HS25)
7. VALVE STEM
X19CrMo VNbN 111 11% Cr, 1% Mo STEEL
8. PRESSURE SEAL PLUG SA 182 F22 (2 1/4% Cr, 1% Mo STEEL)
9. JET CAGE
SA 182 F22 (2 1/4% Cr, 1% Mo STEEL)
HP BYPASS SPRAY AND ISOLATION VALE
1. DESIGN PRESSURRE
281 KG/CM
2. DESIGN TEMPERTURE 170 C
3. MAX. FLOW
39.2 T/HR AT 170 KG/CMAND 141.5 C
4. VALVE TYPE
ON-OFF AND FLOW CONTROL
5. BODY MATERIAL
SA 105(CARBON STEEL)
6. VALVE SEAT
STELLITE - 6
7. STEM
X19CrMo VNbN 111
11% Cr,1% Mo ALLOY STEEL
HYDRAULIC ACTUATOR
1. PISTON SEALS PROVIDED TO
AVOID INTERNAL LEAKGE
BETWEEN TOP AND BOTTOM
OF PISTON.
2. PISTON ROD SEALS AND ‘O’
RINGS PROVIDED TO AVOID
EXTERNAL LEAKGE OF OIL.
BLOCKING ELEMENT - BL10
1. ON-OFF ELEMENT USED FOR SUPPLING OIL (OR)
CUT OFF OIL SUPPLY TO HYDRAULIC ACTUATOR.
2. LOCAL MANUAL OPERATION BY MEANS OF A
LEVER.
3. REMOTE OPERATION BY ENERGISING A
SOLENOID VALVE.
4. SUPPLY VOLTAGE FOR SOLENOID VALVE 48 V DC.
5. ENSURES STAY PUT POSTION OF THE VALVE DUE
TO POWER FAILURE (OR) LOW HYDRAULIC OIL
PRESSURE.
SERVO VALVE St10-4 + R6z, St10-63 + R6z
•
CONVERTS THE CONTROL SIGNAL,FROM THE
CONTROL SYSTEM TO HYDRAULIC OIL PRESSURE.
•
CONTROLS THE OIL ADMISSION TO TOP (OR)
BOTTOM OF ACTUATOR PISTON DEPENDING ON
CONTROL SIGNAL (+) OR (-).
•
CONTROLS VALVE POSITION, ANY WHERE BETWEEN
0-100% POSITION
•
LOCAL MANUAL OPERATION BY MEANS OF LEVERS.
•
REMOTE OPERATION BY THE TORQUE MOTOR R6z
•
SUPPLY VOLTAGE FOR TORQUE MOTOR
(+) OR (-) 10 V DC.
SERVO VALVE
ON-OFF CONTROL UNIT - APL6
1. PROVIDED FOR ON-OFF SERVICE ONLY.
2. KEEPS THE VALVE EITHER IN FULL OPEN OR FULL
CLOSE POSITION ONLY
3. CONSISTS OF ONE NUMBER
* DIRECTIONAL CONTROL VALVE
* TWIN THROTTLE VALVE
* TWIN CHECK VALVE
* MOUNTING MANIFOLD
4. SUPPLY VOLTAGE PLUS (OR) MINUS 48 V DC.
QUICK OPENING DEVICE-SSB10/ SSB16
PROVIDED FOR QUICK OPENING OF HP BYPASS VALVE
WITHEN 3 SEC.
1. FLOW CONTROL VALVE IS PROVIDEDTO ACHIVE
THE QUICK OPENING.
2. TWO PILOT OPERATED CHECK VALVES ARE
PROVIDED TO ENSURE ACTUATOR OIL IS NOT
DRAINED THROUGH SSB10.
3. ON ENERGISING THE SOLENOID OF THE 3/2 WAY
VALVE,HIGH FLOW OIL IS ADMITTED TO THE
ACTUATOR AND THE VALVE OPENS IN LESS THAN 3
SECS.
FAST OPENING OF HP BYPASS VALVE UNDER:
1. GENERATOR CIRCUIT BREAKER OPENS
2. TURBINE TRIPS
3. TIRBINE LOAD SHEDDING REALY ACTS.
OIL SUPPLY UNIT OV32B-50-201
1. SUPPLY OIL UNDER CONSTANT PRESSURE FOR
OPERATING ALL THE VALVE ACTUATORS
2. SUPPLIES REQUIRED QUANTITY OF OIL TO OPERATE
ALL VALVE ACTUATORS
3. OIL IS STORED IN THE ACCUMULATOR,IN THE
COMPRESSED SPACE OF NITROGEN AND SUPPLIED
TO VALVE ACTUATOR.
4. MOTOR RUNNING IS CONTROLLED BY SENSING THE
ACCUMULATOR OIL PRESSURE BY MEANS OF THE
PRESSURE SWITCH.
5. CONSTANT OIL PRESSURE IS ENSURED BY THE
PRESSURE REDUCING VALVE.
POSITION FEED BACK TRANSMITER
1. CONVERTS THE VALVE STEM LINEAR MOVEMENT
TO CURRENT OUTPUT SIGNAL TO INDICATE
VALVE POSITION AT CONTROL ROOM.
2. IN PUT SIGNAL + 15 V DC.
3. OUTPUT SIGNAL 5 TO 15 mA (OR) 4 to 20 mA
HYDRAULIC OIL
1. HYDRAULIC OIL : ISO VG 32 / 46
2. RECOMMENDED OIL : SERVO CONVAL-46
3. OIL TO BE FILTERED THROUGH 3 MICRON
FILTER DURING OF TANK
4. FILTEREABILITY OF OIL TO BE TESTED BEFORE
FILLING.
ABSOLUTE FILTERATION RATING OF FILTERS
(IN MICRONS)
1. AIR FILTER
: 100
2. SUCTION FILTER
: 100
3. HIGH PRESSURE TANK FILTER : 10
4. HIGH PRESSURE LINE FILTER
:
3
5. SINTERED BRONZE FILTER
: 15