TDBFP ROLLING
Topics of discussion:
1.
Introduction
2.
Extraction System
3.
Gland seal steam system
4.
Turbine drains & TDBFP Flash tank
5.
Feed water system
6.
Lube oil system
7.
Start Permissive & Protections
8.
Control System
9.
TDBFP Rolling
2
Introduction
▪ At Lara STPS, 2*50% TDBFP are provided
▪ TDBFP features:
▪ Single Casing , Impulse, Single flow, Condensing, External switch over to CRH Variable speed, Variable power turbine
▪ Rated Speed: 2800 – 6000 rpm
▪ Over speed @ 6180 rpm (MEH), 6185(METS)
▪ Steam Source:
Steam Source
Aux PRDS
CRH -> HP steam*
IPT Extr -> LP Steam# Exhaust
Rated Pressure
1.6Mpa
5 Mpa
0.7MPa
10.75 kPa
Rated Temperature
310 deg C
324 deg C
334 deg C
<80 deg C
* Before External switch valve
# Before LP Main stop valve
▪ Turbine single shaft, single cylinder
▪ Single row governing stage & 5 pressure stage
▪ 5 diaphragms – 4 in front casing, 5th in exhaust casing
3
Extraction Steam System
4
5
▪ Startup vent
▪ Exhaust hood spray
Action
Speed
Auto Open
as per start sequence
Auto Close
Superheat steam temp before stop valve > 56 deg C
Exhaust hood temp
Action
Spray valve Command
< 60℃
stop spraying
0
>70℃
pre‐alarm
20-40%
>80℃
alarm
100%
121℃
trip
6
Gland Seal Steam System
To GSC hdr line
Turbine
SV
Gland steam
FROM
AUX PRDS
M
M
FROM
Drive Turbine
Operating Range:
Pressure - 1.2 – 1.4 ksc
Temperature - 121-150 deg C
CV
Spray water from
Condensate System
M
Gland Steam
Set Point
Low
High
Hdr Pr
1.25 ksc
< 1.17ksc
> 1.38ksc
Hdr Temp
130 degC
<121 degC
>150 degC
Turbine Drains & Flash Tank System
Turbine Drains & Flash Tank System Cont.
Turbine drains:
4 no's drains - All Pneumatic valves
Action
Speed
Auto Open
<3400 rpm
Auto Close
>3691 rpm
Flash Tank drain transfer pumps:
Flash Tank temp control:
Action
Speed
Action
Temp
Auto Start
+150 MM
Auto SP
80 deg C
Auto Stop
-100 MM
High
>90 deg C
FEED WATER
10
Open Permissive
TDBFP
Discharge Valve
TDBFP Disch v/v IBV open
Auto Open
TDBFP sequence cmd to open
BFP reverse rotation acted
Cmd from start sequence OR stop sequence
TDBFP
Discharge Valve
IBV
Auto Open
Auto Close
Auto Close
Open cmd from sequence OR Dish valve open cmd from HMI
Reverse rotation acted OR Close cmd from sequence start / stop OR
TDBFP Disch. Valve open feedback
Recirculation Line
Pneumatic valve. Always open
Suction Valve
Manual Valve. Always open
Speed Vs Suction flow
SPEED
2000
1800
1600
1400
1200
1000
800
600
400
200
0
0
2000
4000
Flow HIHI
6000
Flow LOLO
8000
3000
4000
4805
5148
5198
5386
5390
5623
5702
6185
Suction Flow
Flow Flow
HIHI LOLO
854
252
1214
315
1530
384
1629
411
1638
415
1715
430
1716
431
1763
450
1815
456
1888
494
Turning Gear
LUBE OIL SYSTEM
16
Switch Valve (HGV)
✓ Electric Pneumatic Control Valve
✓ Electric Pneumatic converter + 1 switch valve actuator
✓ HGV is used to maintain pressure before MSV control
✓ Pressure of governing oil provides the force to open or close HGV .
✓ Force provided by HGV actuator is used to open HGV. HGV is closed by the spring force .
✓ Pneumatic positioner -> electric control current from MEH to the displacement of the locating rod to opens or
closes the valve through the piston
✓ When air pressure increases, the pilot valve overcomes the spring force to move downward and open the oil inlets
between the pilot valve and pilot valve bush that are closed to open. pressure oil is connected to the lower part of
oil chamber to increase the pressure of oil under the actuator piston, the actuator piston shaft is pushed to move
upward to open the HGV
Control Valve (LGV)
✓ Electro Hydraulic Control Valve
✓ Electric Hydraulic converter + 1 control valve actuator
✓ 2 parallel fast off solenoid valves
✓ LGV is used to maintain turbine speed.
✓ Force provided by LGV actuator is used to open LGV. LGV is closed by the spring force .
✓ Speed control functional block -> LGV position control function block receives the valve position demand ->
converts to electric signal and sends to LGV actuator -> electric-hydraulic converter from MEH to open the valve > connecting pressure oil to the piston or to close the valve by releasing the pressure oil from the oil chamber
according to the requirements.
Steam Pressure at Stop Valve v/s speed
4
SPEED
Press (Ksc)
0
1.9
3100
1.9
2.5
3300
2.2
2
3500
2.5
1.5
3700
2.75
3900
3.1
5500
3.45
0.5
5700
3.75
0
6185
3.75
3.5
3
1
0
2000
4000
6000
8000
TDBFP Start Permissive:
1) Turbine Brg Drain oil temp not high
< 80 deg C
2) Deaerator Level Not low
>1515 mm
3) TDBFP-A BP Start Permissive:
a)
BP DE/NDE/Thrust Radial Brg temp not hi
< 90 Deg C
b)
BP Suction Strainer DP not hi
< 0.15 Ksc
c)
BP Suction valve open feedback
d)
BP CW flow not low at I/L & O/L of Heat exchanger
e)
BP Lube oil Pr not low at suction of DE & NDE brg
> 1 ksc
f)
BP cooling water temp not high
< 43 Deg C
g)
BP sealing water temp not high
< 55 Deg C
TDBFP Start Permissive Cont.:
4)
Main pump start permissive:
a)
Brg temp not hi (DE/NDE/Thrust)
< 90 Deg C
b)
Suction strainer DP not high
< 0.15 ksc
c)
CW press Not LO at inlet of DE & NDE Brg
d)
LO press at BD & NDE not Lo
e)
Main pump Cooling water flow outlet Not LO.
f)
Cooling water Temp Not high
< 43 Deg c
g)
Sealing water temp Not high
< 55 Deg c
h)
Barrel casing diff Temp Not high.
< 28 Deg c
> 1 ksc
TDBFP Start Permissive Cont.:
5)
Turbine start permissive:
a)
LO Temp Upstream of filter Not high
< 49 Deg c
b)
LO Press & Level OK-
> 2.8 Ksc & 675 mm.
c)
Control Oil header Press not low
> 9.1 ksc
d)
Gear box temp not hi
< 90 deg C
e)
Front /Rear/Thrust Brg metal Temp Not high.< 99 Deg c
f)
Rear casing exhaust Temp
< 80 Deg
TDBFP Start Permissive Cont:
6)
TDBFP speed zero
7)
TDBFP reverse rotation not acted.
8)
TDBFP No protection trip
9)
Condenser Press < 0.4 Ksc.
10) DMCW Pump permit Ok.
11) Vibration Ok. < 76 micron & +/- 0.9mm
12) Discharge MOV & IBV closed
13) R/C valve open.
TDBFP Protection
Sl No Protection
Alarm Value
Trip Value
1
Vibration Trip
76 Micron
120 Micron
2.
Thrust Brg wearing trip
+/- 0.9 mm
+/- 1.2 mm
3.
DCS Protection Trip
a. suction Flow LO LO
As per Speed Curve
b. suction Flow HI HI
As per Speed Curve
c. Deaerator Level LO LO
<-1265mm
d. BP protection
BP DE/NDE shaft Vib- X/Y HI HI.
BP DE/NDE thrust brg temp HI HI
e.
MP protection
MP DE/NDE shaft Vib- X/Y HI HI.
MP DE/NDE/ Thrust brg temp HI HI
75 Micron
90 Deg C
114 Micron.
95 Deg C
75 Micron
90 Deg C
114 Micron.
95 Deg C
TDBFP Protection Cont.
Sl No
Protection
f.
Turbine protection
Rear casing Exhaust Temp HI HI
GB brg Temp HI HI
Front Brg (+ve) Metal Temp HI HI
Front Brg (-ve) Metal Temp HI HI
Front Brg Radial Metal Temp HI HI
Back Brg Radial Metal Temp HI HI
g.
Trip Command (Manual Trip)
h.
BP suction valve not open
Alarm Value
Trip Value
80 deg C
90 Deg C
99 Deg C
99 Deg C
99 Deg C
99 Deg C
121 Deg C
100 Deg C
107 Deg C
107 Deg C
107 Deg C
107 Deg C
5
MEH overspeed Trip
> 6180 RPM
6
METS overspeed trip
> 6185 RPM
7
Lub Oil Press Trip
< 0.23 Mpa
8
Vacuum Trip
9
Local Push Button Trip
10
UCD Trip
11
LCD Button trip
-73 Kpa
-68 Kpa
Hot start up
Warm start up
Cold start up
Speed Close Control Loop:
▪ Speed Control Functional Block:
3 separate speed probe -> median (current speed) Speed CLCS to manual mode:
1.
Manual button by operator
2.
2 out of 3 speed sensors bad
3.
Turbine tripped
4.
Speed deviation i.e. current speed & speed calculated by system > 1000rpm
Control System
Drive Turbine Control System has
▪ MEH -> Micro Electro Hydraulic –
✓ to control the steam inlet flow passing through HGV and LGV
✓ controls drive turbine speed according to FW requirement
▪ METS -> Micro Emergency Trip System
✓ METS first out menu mainly monitors and protects signals that are critical to the safe operation of drive
turbine.
✓ Once any protection reaches trip condition, METS will de-energize the trip solenoid valves to close the steam
valves, trip and protection the drive turbine
▪ MTSI -> Micro Turbo supervisory Instruments
✓ monitors signals of vibration, eccentricity, rotor position, etc
MEH
▪ MEH has two control mode:
a.
b.
Manual
Auto :
✓ OA Control Mode: (Operator Auto) -> speed reference by TCS system
drive turbine speed target and speed changing rate are entered by operator
✓ Remote Control Mode: remote set point by DCS system
speed set point from DCS and generates speed changing rate according to the difference between remote
speed target and speed set point
▪ Purpose:
a.
b.
to control the steam inlet flow passing through HGV and LGV
controls drive turbine speed according to FW requirement
Speed Target from
BFP/ FW Control
Valve Position functional block
Pos feedback-pos demand
MEH PANEL
Speed Control
Functional Block.
Speed Target-Actual
Speed
Valve position demand
Signal to coils of
E/H
CONVERTORS
Speed Control Functional Block:
3 separate speed probe -> median (current speed) -> P&I Calculated with speed reference with speed rate
(operator input of TCS system)
Valve position Functional Block:
pos feedback with pos demand -> signal to coils of EH converter.
NTPC LARA
NTPC Talcher Kaniha
NTPC Tanda
NTPC Talcher Kaniha
NTPC Telangana
THANK YOU
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