UNIT HOT START UP

&
UNIT WITHDRAWL
TURBINE STARTUP

There are three types of the operating mode of the Turbine

• Self starting mode.
• Operator starting mode.
• Manual starting mode.
The operator has to choose any one as per state of unit.

SELF STARTING MODE (Turbine Automatic Control (ATC) Mode).

• ATS (Automatic Turbine system) of DEH perform the function of

complete startup process i.e. selection of the Turbine startup state
(cold startup, warm startup, hot startup or extremely hot startup),
Turbine rolling, Synchronization and initial loading of the Turbine to
rated load.
OPERATOR STARTING MODE (Operator Automatic Operating Mode)
• Operator during rolling, manually selects the startup state, Target
speed, rate of speed / load rise according to the actual status of the
Turbine (Turbine first stage temp, Casing temp, Top and bottom
temperature).
• The basic function of ATS of DEH is to complete the function of the
rolling, auto synchronization & load raising as per given set points.
• During speeding / loading of turbine if set value (of rise rate) is more
than the calculated rise rate by ATS (calculation by “Stress
Computing System”), then ATS will give command to DEH to follow
the lower value out of two.
• Also monitor the Critical speed criteria. (1370, 1688 & 1750 rpm).
• During the startup process the DEH monitors the actual status and
gives alarm or trips turbine if any deviation exist from the rating.

MANUAL MODE.
• In manual mode all the operations are performed manually by the
operator.
• The operator controls the Turbine by varying the control valve
position from the control desk. All plant startup activities like unit
rolling, synchronization and load pick up done manually.
The start up of turbine is decided by metal temp. of upper inner wall of
HP Cylinder
• Start-up under cold state ≤150°C
• Start-up under warm state = 150 ~ 300 °C
• Start-up under hot state = 300 ~ 400 °C
• Start-up under extremely hot state ≥400 °C
IP START UP

• IP casing startup shorten the unit startup time and save the startup
cost.
• Startup with IP casing is used to utilize the REHEAT STEAM
which has higher temperature and flow which is helpful in
raising the temperature rapidly. This startup increases HP
exhaust temperature, so care must be taken to prevent the
excessive increase in the exhaust temperature.
• Steam is leaked out from between the steam seals of HP/IP casings
enters into the HP casing from IP casing during startup through IP
casing, to warm up the cylinder; whereas during normal operation,
the steam leaks from HP casing to IP casing.
• For taking IP startup mode in the service the bypass condition
must have the capacity of the 35% of MCR flow and the bypass
should be in auto mode.
• Prior to turbine rolling, the steam downstream the HP bypass valve
enters through reverse flow valve (RFV) in the HP casing to preheat
the HP casing & then enters IP casing through seal steam between
the HP/IP casings for preheating.

• Ensure that the cylinder internal pressure is at 0.4~0.5MPa through

adjusting the reverse flow valve and drain valve and fulfill the
cylinder warm-up through heating.

• During HP casing pre-warming, open 10% of the HP main steam

valve 2 to pre-warm the HP main steam valve casing, MS valve
chest and the main steam pipe. The pre-warming steam pressure is
0.4~0.8MPa, the temperature is 200 ~250 °C, and a superheat of 50
°C is maintained.
IP Startup Mode
Warm Start Up

Ensure the following systems are running normally.

1. CCCW & ACW system.
2. Compressed air system.
3. Fuel oil system
4. Lube oil system, jacking oil system, seal oil system.
5. Barring gear system, generator H2 gas system.
6. Condensate system, feed water system, auxiliary steam system.
7. Turbine gland seal system, vacuum is pulled to less than 16.7
kPa.
Boiler light up & Pressurizing.
1. Furnace oil leak test.
2. Boiler purge.
3. Boiler light up.
a. At 0.15 ~ 0.2 MPa; close drum, S/H, R/H vents.
b. Open HPBP & LPBP slightly at MS Pr. 0.1MPa
c. At 0.5 MPa close start up vents.
d. Give IBD at 0.5, 1.0 & 2.0 MPa.
e. Start CBD at 1.0MPa.
4. Record the various parameter as MS/RH Pr. & Temp., Vacuum,
5. Go on adding fuel in boiler as per requirement of steam
parameters raising.
 Parameters Required Before Rolling

IP START HP & IP START

Warm Start Up Warm Start Up
MS Pr.= 5.88 MPa, T= 370 0C, MS Pr.= 7.84 MPa, T= 410 0C,
RH Pr.= 0.686 MPa, T= 327 0C. RH Pr.= 0.686 MPa, T= 327 0C.

Hot Start Up Hot Start Up

MS Pr.= 7.84 MPa, T= 450 0C, MS Pr.= 9.81 MPa, T= 450 0C,
RH Pr.= 0.883 MPa, T= 417 0C. RH Pr.= 0.883 MPa, T= 417 0C.

Extr. Hot Start Up Extr. Hot Start Up

MS Pr.= 9.81 MPa, T= 460 0C, MS Pr.= 11.76 MPa, T= 510 0C,
RH Pr.= 0.883 MPa, T= 417 0C. RH Pr.= 0.883 MPa, T= 487 0C.
 IP Start Mode
Warm Startup
Ensure the Gland steam Pr = 0.123MPa & T = 150~260°C,
Vacuum < 16.7KPa

1. Latch the turbine,

2. Open Drains of HP, IP, LP section,
3. TSI parameters within permissible range,
4. Confirm the CRH NRV is closed,
5. Pre warm HP casing till upper inner casing temp. reach 150 °C,
6. Steam Parameter for Turbine rolling.
• MS Pr = 5.88MPa, T = 370 °C
• RH Pr = 0.686MPa, T = 327 °C
7. As MS Pr. increases to 5.88 MPa put HPBP on auto & when RH
steam Pr increase to 0.686MPa put LPBP in auto mode with
above steam parameter as set point.
 Turbine Rolling
• Confirm slide valve of emergency gov. is engaged (Latched).
• Confirm whether the “HP & IP START / IP START” button is under
the “IP START” mode.
• Confirm HPBP and LPBP valve should be in the AUTO.
• Press RUN button & IP SVs are opened.
• Give prewarming through MSV2 as per requirement.
• During this period if turbine speed increases to 10 rpm, turbine trip
as CVs are passing then.
• During rolling if actual speed raises 500 rpm more than target speed
then turbine trip.
• Give target speed of 500 rpm @ accln rate of 200rpm/min.
• IP CVs open gradually
• Confirm VV is closed.
• Press ‘GO’. Speed increases and barring gear is cut off.
• Inspection at 500 rpm, Waiting time < 5 min.
• Vacuum < 13KPa.
• Give target speed of 3000 rpm @ acceleration rate of 200rpm/min
• Based on the metal temperature of HP exhaust lower half inner
wall, control the temperature to reach 200°C by adjusting the
opening of ventilator valve.
• Press “GO” , Watch speed rise, JOP & AOP cut off at set speed.
• Give soaking for 10 min.
• Watch the TSI parameters within permissible limits.

Synchronization
• Synchronize the unit, initially 3% of rated load (9MW) will be
achieved.
• Raise load to 30MW at 3 MW/min.
• Change over between HP and IP Casings at 30 ~ 40 MW.
• Select load rise rate of 3MW/min.
 Casing Metal Temp. At Various
Locations
B0
A0

C0 A0 - A1 < 50°C
C1
B0 - B1 < 50°C
P0
C1 - C0 < 35°C
E0 P1 - P0 < 35°C
P1
E1 - E0 < 80°C
E1

B1 A1
Change over between HP and IP Casings.

a. Before changing over between HP and IP casings, matching of the

MS temperature and RH temp is done as per graph provided.

b. When it is changed from the sole steam admission through the IP

casing to the combined steam admission through the HP and IP
casings, the parameters and flows of main steam and reheat steam
shall be kept stable initially.

c. Perform warming up at low load. Monitor the metal temperature of

HP exhaust lower half inner wall. It shall reach @170 °C. Adjust the
opening of ventilator valve to control the metal temperature of HP
exhaust lower half inner wall within 220--250 °C for 15 min;
d. When all the above conditions are fulfilled, the operator presses the
"VALVE CHANGE" button to change the valves. The HP control
valve gradually opens in the mode of single valve. After about 1 min,
the HP and IP control valves start to enter into proportional
relationship and the change is over then.

e. Check the following conditions during the change over period:

(1) The CRH NRV opens automatically.
(2) The ventilator valve (VV valve) is closed.

f. Check for engaging of the interlayer heating device based on the HP

casing temperature and DE.

g. When the change over is completed, the DEH system sends signals
to increase load. With the increase of load, the HP by-pass
closes gradually.
• The downslide point is reached at 135MW, then load rise is due to
Pr rise of boiler.
• Check for stopping of cylinder inter layer heating when metal
temperature of lower half of HIP outer casing (Point B1in figure)
exceed 3500C & HIP differential expansion is in the permissible
range.
• Check the close sequence of drain valves.
a. At 10 % rated load, HP drains closed.
b. At 20 % rated load, IP drains closed.
c. At 30 % rated load, LP drains closed
• When 60% load is reached & Temp. of turbine proper is stable
change to SEQUENCE valve mode for better economy.
Slide Pressure Operation
Hot & Extremely Hot start up (IP Start)
Ensure the following systems are normal before startup
– Supply to DEH
– Lube oil, Jacking oil system and Barring
– EH oil system
– Gland steam Pr. = 0.123MPa & T = 250~350°C.
– Vacuum < 16.7KPa
1. Latch
2. Open Drains of HP, IP, LP section
3. TSI parameters within permissible range
4. If ∆T between rolling steam & MSV Metal temp. is > 120 °C, Valve
should be preheated
5. Confirm CRH NRV is closed
6. Steam Parameter for Turbine rolling.
Hot State Extr. Hot
State
• MS Pr. = 7.85 MPa, T = 450 °C Pr. = 9.81MPa, T = 460 °C
• RH Pr. = 0.883MPa, T = 417 °C Pr. = 0.883MPa, T = 417 °C
7. As MS Pr. increases to 7.85 MPa put HPBP on auto & when RH steam
Pr increase to 0.883 MPa put LPBP in auto mode with above steam
parameter as set point.
 Turbine Rolling
• Confirm slide valve of emergency gov. is engaged.
• Confirm whether the “HP & IP START / IP START” button is under
the “IP START” mode.
• Confirm HPBP and LPBP valve should be in the AUTO.
• Press RUN button & IP SVs are opened
• Give target speed of 500 rpm @ accln rate of 200rpm/min for hot
start up & 300rpm/min for Extr. hot start up.
• IP CVs open gradually
• Confirm V V is closed.
• Speed increases and barring gear is cut off.
• Inspection at 500 rpm, Waiting time < 5 min.
• Vacuum < 13KPa.
• Give target speed of 3000 rpm @ acceleration rate of 300rpm/min
• Based on the metal temperature of HP exhaust lower half inner wall,
control the temperature to reach 200°C by adjusting the opening of
ventilator valve.
• Press “GO” , Watch speed rise, JOP & AOP cut off at set speed.
• Watch the TSI parameters within permissible limits.
 Synchronization
• Synchronize the unit, initially 3% of rated load(9MW) will be
achieved.
• Raise load at 4.8 MW/min. for hot state & 7 MW/min. for Extr. Hot
state.
• Raise load to 30MW.
• Change over between HP and IP Casings.
• The downslide point is reached at 165MW, then load rise is due to
Pr. rise of boiler.
• Check the close sequence of drain valves.
a. At 10 % rated load, HP drains closed.
b. At 20 % rated load, IP drains closed.
c. At 30 % rated load, LP drains closed
• When 60% load is reached & Temp. of turbine proper is stable
change to SEQUENCE valve mode for better economy.
 HIP Start Up Of Turbine
Warm Start Up.
Ensure the following systems are normal before startup
– Supply to DEH
– Lube oil, Jacking oil system and Barring
– EH oil system
– Gland steam Pr. = 0.123MPa & T = 150~260°C.
– Vacuum < 16.7KPa
1. Latch
2. Open Drains of HP, IP, LP section
3. TSI parameters within permissible range
4. Steam Parameter for Turbine rolling.
• MS Pr. = 7.84MPa, T = 410 °C
• RH Pr. = 0.686MPa, T = 327 °C
•
Turbine Rolling
Confirm slide valve of emergency gov. is engaged. (Latched)
• Apply cylinder interlayer heating (Watch DE.).
• Confirm whether the “HP & IP START / IP START” button is under
the “HP & IP START” mode.
• Select Single valve mode.
• Press RUN button, HP & IP SVs are opened.
• During this period if turbine speed increases to 10 rpm, turbine trip
as CVs are passing then.
• In case actual speed raises 500 rpm more than target speed then
turbine trip.
• Give target speed of 500 rpm @ acceleration rate of 150rpm/min.
• HP & IP CVs open gradually.
• Speed increases and barring gear is cut off at 4.12rpm.
• Inspection at 500 rpm, Waiting time < 5 min.
• Check VV & BDV are closed.
• Vacuum < 13KPa.
• Give target speed of 3000 rpm @ acceleration rate of 150rpm/min
• Press “GO” , Watch speed rise, JOP & AOP cut off at set speed.
• Give soaking for 15 min.
• TSI parameters within permissible limits.
 Synchronization
• Synchronize the unit, initially 3% of rated load(9MW) will be
achieved.
• Raise load to 30MW at 3 MW/min.
• Warming at 30 MW for 20 min.
• Select load rise rate of 3MW / min.
• The downslide point is reached at 135MW, then load rise is due
to Pr. rise of boiler.
• Stop cylinder inter layer heating.
• Check the close sequence of drain valves.
a. At 10 % rated load, HP drains closed.
b. At 20 % rated load, IP drains closed.
c. At 30 % rated load, LP drains closed
• When target load is reached & Temp. of turbine proper is stable
change to SEQUENCE valve mode for better economy.
Hot & Extremely Hot start up (HP & IP Start)

Ensure the following systems are normal before startup

– Supply to DEH
– Lube oil, Jacking oil system and Barring
– EH oil system
– Gland steam Pr. = 0.123MPa & T = 250~350°C.
– Vacuum < 16.7KPa
1. Latch
2. Open Drains of HP, IP, LP section
3. TSI parameters within permissible range
4. If ∆T between rolling steam & MSV. Metal temp. is > 120 °C, Valve
should be preheated
5. Steam Parameter for Turbine rolling.

Hot State Extr. Hot State

• MS Pr. = 9.81MPa, T = 450 °C Pr. = 11.76MPa,
T = 510 °C
• RH Pr. = 0.883MPa, T = 417 °C Pr. = 0.883MPa, T = 487
°C
 Turbine Rolling
• Confirm slide valve of emergency gov. is engaged.
• Select HP & IP Start mode.
• Select Single valve mode.
• Press RUN button, HP & IP SVs are opened
• Give target speed of 500 rpm @ accln rate of 200rpm/min for hot
state & 300rpm/min. for extr. Hot state.
• HP & IP CVs open gradually
• Speed increases and barring gear is cut off at 4.12rpm
• Inspection at 500 rpm, Waiting time < 5 min.
• Check VV & BDV are closed.
• Vacuum < 13KPa.
• Give target speed of 3000 rpm @ acceleration rate of 300rpm/min
• Press “GO” , Watch speed rise, JOP & AOP cut off at set speed.
• TSI parameters within permissible limits.
 Synchronization
• Synchronize the unit, initially 3% of rated load(9MW) will be
achieved.
• Raise load at 4MW/min. for hot state & 6 MW/min. for extr. Hot
state.
• The downslide point is reached at 165MW, then load rise is due
to Pr. rise of boiler.
• Check the close sequence of drain valves.
a. At 10 % rated load, HP drains closed.
b. At 20 % rated load, IP drains closed.
c. At 30 % rated load, LP drains closed
• When 60% load is reached & Temp. of turbine proper is stable
change to SEQUENCE valve mode for better economy.
 Unit Withdrawing
The shutdown mode for this unit are
1. Shutdown at sliding parameters.
– Mainly to reduce the cylinder metal temperature to a lower
level during unit withdrawing. Normally it is preferred for
planned shutdown when heavy (Time consuming) repair
works to be taken up.
2. Shutdown at rated parameters.
– Mainly to enable early start-up after short time fault
attending (Very short shutdowns). Therefore, it is desired
to maintain a higher temperature level for the cylinder
metal to shorten the startup time.
3. Emergency shutdown.
- It mainly applied when sudden plant emergency
occur in
case of breakdowns.
 Shutdown at sliding parameters.
1. Limitations for the reduction of temperature, pressure and
load in accordance with boiler shutdown curve at sliding
parameters.
• Decreasing rate of main steam and reheat steam
temperature < 1°C/min.
• Decreasing rate of main steam and reheat steam
pressure < 0.098MPa/min.
• Decreasing rate of cylinder metal temperature < 1°C/min.
• Degree of superheat of main steam and reheat steam > 50°C.
• When the main steam temperature falls by about 30°C, the
temperature shall be kept for 5~10min before further reduction for
controlling the temperature difference of main steam and reheat
steam as well as the DE.
• Stop reducing steam temperature when it falls to 30°C lower than
the metal temperature of flange inner wall (Point E1in figure) at the
control stage of HP inner casing after the control stage.
• During the load decrease, the by-pass system shall be put into
service according to operation condition.

2. Observe for drains system operation during load decrease

• LP section drains open at 30% rated load;
• IP section drains open at 20% rated load;
• HP section drains open at 10% rated load.

3. When the pr.& temp of steam falls to 4.9 ~ 5.88MPa &

330 ~360°C resp, decrease the load to 5% rated load at constant
pressure, Trip the unit.
• Check that MSV, RSV, MS & RS CVs, Extrn & CRH NRV are
closed.
• Check for pick up of AOP, JOP & Barring at respective speeds.
 Shutdown at Rated Parameters
• For the unit which need shutdown just for a few hours or other transient
temporary shutdown, in order to have the metal temperature higher after
shutdown which is in favor of restarting quickly.

• Select 1MW/min as the rate of load decrease.

• Put the by-pass system into service at any moment according to boiler
operating condition.

• During load decrease, pay attention to the DE changes of HIP casing and LP
casing, if the expansion difference is too big, the speed of load decrease shall
be slowed down.

• The change-over of steam source at shaft seal shall be noticed.

• Stopping the load decrease and keeping steady operation when the DE
reaches -1mm, if the negative DE continue to increase and no measure is
useful, in order to ensure the safety of unit, the load shall be decreased to
zero rapidly or trip the unit.

• When the load decreases to 5% of rated load, trip turbine and Check that
MSV, RSV, MS & RS CVs, Extrn & CRH NRV are closed.
MS temp calculation. ( For HIP warm Startup)

• Metal temperature required after the control stage of HP casing

before turbine rolling = 180 0C

• According metal properties max deviations allowed by

manufacturer (depends on type of rolling) = 130 0C

• Steam temperature after the control stage = 310 0C

• Main steam temperature = 410 0C (From graph depending on max
temp drop).
THANK YOU.