HP/LP BYPASS SYSTEMFUNCTION:

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: E32S+ASM100-10/SK 200

3. HP BYPASS ISOLATION VALVE: 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