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HP-LP Bypass System HP Bypass Valve HP Bypass Spray Valve LP Bypass Valve LP Bypass Spray Valve Electro Hydraulic Actuating System HP-LP Bypass System HP/LP Bypass System
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HP LP Bypass system (Turbine)

Mar 04, 2015

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Debasish Dewan
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Page 1: HP LP Bypass system (Turbine)

HP-LP Bypass System

HP Bypass Valve

HP Bypass Spray Valve

LP Bypass Valve

LP Bypass Spray Valve

Electro Hydraulic Actuating System

HP-LP Bypass System

HP/L

P B

ypass

Sys

tem

Page 2: HP LP Bypass system (Turbine)

HP-LP Bypass System

High pressure (HP) and Low pressure (LP) bypass systems are

used for quick start-up of the unit as well as during trip-out, where

load rejection at the turbine does not automatically lead to a boiler

trip. With a bypass system, start-up is quicker. The system diverts

the steam generated by the boiler to the Re-heater/Condenser, at

the same time reducing the pressure and temperature of steam,

thus maintaining a minimum circulation of steam through the boiler.

This enables running the boiler without the turbine in service,

ensuring flow through re-heater coils.

BHEL HP-LP bypass system has the following advantages :

The prolonged venting of safety valves to atmosphere is avoided,

thereby reducing DM water loss and cutting noise emission.

HP-LP Bypass System

Contd...

Page 3: HP LP Bypass system (Turbine)

HP-LP Bypass System

HP-LP Bypass System

Sustained flow through the boiler heating surfaces is

assured, ensuring Re-heater protection during start-up of

units.

If the grid cannot accept power, the unit can be kept

running on house load.

Almost all power plants are provided with HP-LP bypass

systems for technical and economical reasons. The

technology has been obtained from SULZER

THERMTEC, Switzerland and we manufacture all the

components in-house.

BHEL has supplied bypass systems to

over 150 power plants of 120/210/250/500 MW rating with

a total installed capacity of over 32,000 MW.

Page 4: HP LP Bypass system (Turbine)

BOILER

BP

MSL

HRH

HPT

CRHNRVCRH

BPE

BD

LPC

LBP

M P T LPT

CON

LBPE

BFP

LEGEND

BP - HP BYPASS VALVE

BD - SPRAY WATER ISOLATION VALVE

BPE - SPRAY WATER FLOW CONTROL VALVE

LBP - LP BYPASS VALVE

LPC - LP COOLER

LBPE - LP BYPASS SPRAY VALVE

HPT - HIGH PRESSURE TURBINE

MPT - MEDIUM PRESSURE TURBINE

LPT - LOW PRESSURE TURBINE

CRHNRV - CRH NON RETURN VALVE

BFP - BOILER FEED PUMP

CON - CONDENSER

MSL - MAIN STEAM LINE

HRH - HOT REHEAT LINE

CRH - COLD REHEAT LINE

HP-LP Bypass System

HP-LP Bypass System

Page 5: HP LP Bypass system (Turbine)

Model Nos: ARS 45, ARS 50, ARS 63,

ARS 72, ARS 80, ARS 90, ARS 100,

ARS 112, ARS 140 & ARS 140A

HP Bypass Valve

HP-LP Bypass System

l Combined pressure reducing and de-superheating valve.

l Steam pressure reduction by throttling and temperature reduction by spray water injection

l To suit varying high pressure and temperature, the valve body is made from forged material of 2¼ Cr 1 Mo steel (A182 F22 Cl.3).

l To keep the stresses in optimum level, valve body is made of spherical shape.

l Leak tight seat. (HS 25)

l Stem is made from high chrome alloy steel11 Cr 1 Mo (X19CrMoVNbN111).

l Design pressure : 200 kg/sq.cm

l Design temperature : 545°C

Page 6: HP LP Bypass system (Turbine)

l For spray water flow control to HP Bypass Valve.

l Pressure reduction & flow control achieved in three stages to avoid erosion due to high pressure drop.

l Valve body is of "Z" configuration made from forged carbon steel A 105.

l Stem is made from high chrome alloy steel 11Cr 1Mo (X19CrMoVNbN111)

l Leak Tight Stellite Seat.

l Design pressure : 350 kg/sq.cm

l Design temperature : 300°C

HP Bypass Spray Valve

Model No : E22S, E32S, E45S

HP-LP Bypass System

Page 7: HP LP Bypass system (Turbine)

l Pressure reducing valve.

l Steam pressure reduction by throttling.

l Valve body is made from forged material of 2¼ Cr 1 Mo steel (A 182 F 22 Cl.3)

l Stem is made from High Chrome alloy steel 11Cr 1 Mo (X19CrMoVNbN111)

l To keep the stresses at optimum level, valve body is spherical in shape.

l Leak tight seat.

l Design Pressure : 64 kg/sq. cm

l Design Temperature : 540°C

LP Bypass Valve

Model No : NR 64-500 EK

HP-LP Bypass System

Page 8: HP LP Bypass system (Turbine)

HP-LP Bypass System

l For spray water flow control to LP Bypass valve

l Valve body is made from forged Carbon steel A 105.

l Stem is made from High Chrome alloy steel 11Cr 1 Mo (X19CrMoVNbN111)

l Leak tight seat.

l Design Pressure : 50 kg/sq. cm

l Design Temperature : 300°C

LP Bypass Spray Valve

Page 9: HP LP Bypass system (Turbine)

HP-LP Bypass System

44

11

7

33

44

55 66

88

22

Electro Hydraulic Actuating System

Electro hydraulic actuating system is a complete modular unit

with a wide range of actuator cylinders (type ASM) having a

force of about 100 tonnes and large stroke.

It consists of an Actuator cylinder (type ASM), Oil supply unit

(type OV 32B), Servo valve (type ST), Blocking unit (type BL),

Step control unit (type APL), Quick stroking device (type SSB).

Each actuator is equipped either with one Servo valve and

Blocking unit or a step control unit.

Servo valve and blocking element control the open/close and

stay-put function of the valves.

Hydraulic oil required under

high pressure for the

operation of the valves under

high steam pressure is

supplied by the Oil supply unit.

1. Actuator cylinder, type ASM

2. Oil supply unit, type OV 32B

3. Servo valve, type ST

4. Blocking unit, type BL

5. Step control unit, type APL

6. Connection plate

7. Additional accumulator

8. Quick stroking device, type SSB