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
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...
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.
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
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
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
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
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
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