31 3000 9080 e 2004 12
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DRAWING/DOCUMENT STATUS
A
FOR REFERENCE
2006-04-10
First issue
Steenmeyer
DATE
DESCRIPTION
Bearb.
Coord.
Rev.
Liedtke
Sudhoff
Geprüft
Checked
APPD.
PROJECT :
CAMAU 1 750MW COMBINED CYCLE POWER PLANT
OWNER :
OWNER’S ENGINEER :
PETRO VIETNAM
CPMB
CONTRACTOR :
CONTRACTOR’S ENGINEER :
LILAMA CORPORATION
FICHTNER
SUBCONTRACTOR’S NAME :
SUBCONTRACTOR’S SUPPLIER :
s
FEAG
POWER GENERATION
DRAWING TITLE :
System Description Combustion Chamber Instrumentation
PKZ
UAS
Contents Code
Ursprung/Original
Reg. No.
UNID
Urspr.-PKZ-Nr.
Orig.-PC
Ursprung-Nr./Original-No.
Projekt/Project
gezeich.
Drawn
bearb.
Coord.
geprüft
Checked
Abtlg.
Dept.
PKZ/PC
Datum
Date
Name
06-04-10
STEENM
06-04-10
LIEDTKE
06-04-10
SUDHOFF
P415
sgd.
s AG
POWER GENERATION
CA MAU 1 CCPP
VIT154
Maßstab
Scale
UA/DCC
Type
Inhaltskennzeichen
Contents Code
N/A
A4
Benennung/Title
System Description Combustion
Chamber Instrumentation
Dienstst./Dept.
P415
UNID
423217078
XS00
MBM1
Zähl.-Nr.
Reg.-No.
Index/Rev.
355020
Version
A
Blatt-Nr./Page-No.
CM1-L1-M-MBM1.08-355020
Erstellt mit/designed with
Ersatz für
Supersedes
0 of 4
Gas turbine
Description of Auxiliary Systems
Combustion Chamber
Combustion Chamber Instrumentation
Refer also to:
“RELATIVE COMBUSTION
DROP
List of Control Settings (SREL)
List of Measuring Instruments
P+I Diagram, Gas Turbine
P+I Diagram, Combustion Chamber
3.1-0210
3.1-0220
3.1-1010
3.1-3010
If a positive or negative measuring range violation is
detected for measuring point MBA12CP101 or
MBM10CP101, the individual alarm “HYBRID BURNER
DATA ACQUISITION FAULTED” is annunciated.
Flame Monitoring
Fuel must never be fed into the gas turbine combustion
chamber for an impermissibly long period without
combustion taking place. The purpose of flame monitoring
is to determine whether the main fuel is in fact burning in
the combustion chamber, i.e., whether a flame is present.
On fuel oil startup, the ignition gas flame must not trigger
the signal “FLAME ON”.
Function
The reproduction, transmission or use of this document or its
content is not permitted without express written authority.
Offenders will be liable for damages. All rights, including
rights created by patent grant or registration of a utility model
or design, are reserved.
The tasks of the measuring instruments associated with
the combustion chamber system are described in this
Section. These measuring instruments are used to detect
the pressure drop across the combustion chamber,
combustion process instabilities (known as humming),
flashback, and flame out.
Flame detectors are mounted on the combustion
chamber for this purpose, their signals are processed in the
respective evaluation units (generation of limits). These
limits are used by the downcircuit interlock logic for
actuating the fuel shutoff valves.
Pressure Drop across the Combustion
Chamber
When the gas turbine is started up on fuel oil, ignition
gas is briefly used to ignite the fuel oil flames in the
combustion chamber. Because the ignition gas and natural
gas flames have a nearly identical radiant intensity, an
evaluation unit with sensitivity set to detect natural gas
flames may also be triggered by ignition gas flames to
issue a “FLAME ON” signal.
Wear phenomena can occur during long-term operation
of the gas turbine (for example, increased gaps in the
combustion chamber hot gas casing). As a result of these
wear phenomena, less air reaches the burners. This
jeopardizes stable premix combustion.
The relative combustion chamber pressure drop can
generally be considered an indication of combustion
chamber cooling air and combustion air flows. It is
dependent on the combustion chamber geometry, but in
the upper load range is virtually independent of the
momentary GT output. The relative combustion chamber
pressure drop changes as a result of wear or damage to
the burner or combustion chamber parts (changes in
geometry, changes in flow cross-section). Long-term
monitoring of the relative combustion chamber pressure
drop is performed to assess the condition of the
combustion chamber.
In the event that fuel oil flames fail to ignite, it is
possible that unburned fuel oil could continue to be carried
into the combustion chamber and exhaust section (boiler)
beyond the end of the ignition monitoring period.
A separate flame monitoring system is therefore
provided for each fuel to ensure that fuel oil and natural
gas flames are reliably detected.
Flame monitoring employs two flame detectors located
somewhat offset from one another on the circumference of
the combustion chamber. Each is mounted tangentially and
monitors formation of the respective flames in the
combustion chamber. A group of about 2 – 4 burners is
covered by each flame detector.
The differential pressure across the combustion
chamber ∆pCC is measured by differential pressure
transducer MBM10CP101 (cf. 3.1-3010) and compressor
outlet pressure pCII (absolute pressure) by pressure
transducer MBA12CP101 (cf. 3.1-3010). Signals from
these instruments are used to calculate the relative
combustion chamber pressure drop (in percent):
Each flame detector consists of an optical sensor unit
and an optoelectronic converter comprising two photosensitive elements. These 2-color sensors cover the
spectral range from UV to IR. For this reason it is possible
to monitor all types of fuel including gas.
∆pCC rel. = (∆pCC/pCII) x 100%
Class: RESTRICTED
PRESSURE
Monitoring of Measuring Points
Settings, limits, and measuring ranges of the items of
equipment referred to here are given in the List of
Measuring Instruments and List of Control Settings (SREL).
This description only gives guideline values.
The intensity of the light emitted by the combustion
flames is subject to stochastic scattering (for example
caused by non-uniform supply of combustion air or the flow
of fuel). Because of this characteristic of flame radiation,
If the relative combustion chamber pressure drop
declines below limit PP.BK.01 for more than 5s at speeds
above the turbine speed S.TURB.70, the individual alarm
Siemens AG
Power Generation
CHAMBER
3.1-3000-9080/1
MBM
1204E-X
Gas turbine
Description of Auxiliary Systems
Combustion Chamber
Combustion Chamber Instrumentation
elapsed or at any time during subsequent operation on fuel
oil, the supply of fuel is shut off by trip.
the flame sensor distinguishes between uniform light (for
example radiation of the combustion chamber lining) and
light emitted by flames. Signals from the uniform light
sources are not registered by the flame detector.
The fuel oil flame monitors are set such that the ignition
gas flames do not cause annunciation of the signal “FO
FLAME ON”.
The optical sensor unit and the optoelectronic converter
are not housed in a common enclosure. The flame signal is
fed from two sensor units via fiberoptic Y-cables to four
optoelectronic converters. The optoelectronic converters
convert radiant energy into electric signals that are
forwarded to the evaluation units. Two of the evaluation
units are set to the intensity of natural gas flames and two
to the intensity of the fuel oil flames.
Flame Monitor Signals on Fuel Changeover
When a second fuel valve opens (NG ESV OPEN and
FO DM ESV OPEN), all four flame monitors are active.
Consequently the lower sensitivity of the natural gas flames
has priority for the duration of the fuel changeover. Trip is
triggered if none of the four flame monitors signal “FLAME
ON”.
The reproduction, transmission or use of this document or its
content is not permitted without express written authority.
Offenders will be liable for damages. All rights, including
rights created by patent grant or registration of a utility model
or design, are reserved.
The following tasks are performed by the evaluation
units:
−
Monitoring and evaluation of flame detectors
−
Setting the flame identity signals (natural gas and fuel
oil)
−
Generation of limits for the signal “FLAME ON”
−
Monitoring the function of the evaluation units.
Monitoring of Flame Monitors
In the event of conflicting signals from the two flame
monitors for a given fuel (fuel oil or natural gas), the alarm
“FLAME MONITORING FAULTED” is annunciated after a
delay of K.FLAMM.01 has elapsed. The period
K.FLAMM.01 must be somewhat longer than the ignition
flame cutout safety delay.
The evaluation units are equipped with changeover
contacts and internal relays route the detected flame
signals into the I&C system via the respective normallyopen relay contacts. If a flame signal is detected and then
exceeds an adjustable limit, the changeover contacts close
(“FLAME ON”). If the flame signal drops below the nonadjustable limit, the changeover contacts open (“FLAME
OFF”). The magnitude of the switching hysteresis varies
with the difference between the lower, fixed limit and the
upper, adjustable limit. Opening of the changeover
contacts only occurs when violation of the lower limit
persists for longer than one second.
The non-coincidence monitoring alarm of the fuel oil
flame monitors is suppressed during operation on natural
gas to prevent response of non-coincidence monitoring of
the fuel oil flame monitors in this mode.
Monitoring of the Combustion Chamber,
Acceleration and Humming
Combustion instability is manifested in gas turbines by
increased combustion chamber pressure fluctuation
amplitudes, also known as humming, and/or combustion
chamber accelerations.
High acceleration levels must be promptly detected and
suppressed to prevent damage to the gas turbine. This is
achieved by:
Operational Functions
Natural Gas Startup and Operation of the Gas Turbine
on Natural Gas
Natural gas is supplied to the diffusion burners to ignite
the flames. Each natural gas diffusion burner is equipped
with two ignition electrodes that are supplied with voltage
for a defined period. If the signal “NG FLAME ON” is not
issued by both natural gas flame monitors after the ignition
flame cutout safety delay has elapsed or at any time during
subsequent operation on natural gas, the supply of natural
gas is shut off by trip.
Class: RESTRICTED
Changeover to diffusion mode (fuel oil)
−
Output reduction
−
Triggering of trip.
Acceleration is detected using piezoelectric sensors
MBM10CY101 to MBM10CY103 mounted on the
combustion chamber.
To protect the gas turbine, measurement of combustion
chamber acceleration is implemented in all machines with
tiled annular combustors; in addition, the duration of
acceleration is recorded cumulatively. Combustion
chamber tiles must be inspected if the cumulative durations
of these phenomena exceed certain limits.
Fuel Oil Startup and Operation of the Gas Turbine on
Fuel Oil
Ignition gas (for example, propane) is fed to the natural
gas diffusion burners to ignite the fuel oil. If the signal “FO
FLAME ON” is not issued by both fuel oil flame monitors
after the stipulated ignition flame cutout safety delay has
Limits GW1 to GW4 (acronym based on the German
term) are generated from the average of the abovementioned measurements for acceleration monitoring
purposes.
Siemens AG
Power Generation
−
3.1-3000-9080/2
MBM
1204E-X
Gas turbine
Description of Auxiliary Systems
Combustion Chamber
Combustion Chamber Instrumentation
Operation on Fuel Oil
At speeds above S.TURB.70, limits GW1 and GW2 as
well as acceleration monitoring are enabled, however they
are initially suppressed for delay K.BRACC.03.
If violation of limit GW1 persists for duration K.ACC.01,
output is abruptly reduced by the increment E.LEIST.32. If
violation of this limit persists, output is again reduced
repeatedly and abruptly by the same increment each time
K.BRUMM.05 has elapsed. If violation of this limit persists
despite several output reductions, rapid changeover to
diffusion mode is initiated after time periods K.BRUMM.09
and K.ACC.01 have elapsed. If the gas turbine is being
operated with water injection at this time, the water
injection system is automatically tripped to prevent
extinguishing of the flames.
Limit GW1 is suppressed for the time period
K.BRACC.01 during activation and deactivation of
water/emulsion injection when operating on fuel oil. GW1 is
not suppressed in the event of water injection system trip,
because this trip can also be caused by measures to
suppress combustion chamber acceleration.
Limits GW1 and GW2 are suppressed for the duration
of changeover FO DM ↔ FO PM using a staggered
deactivation delay of K.ACC.06. Analogously time interval
K.ACC.05 is used in the case of changeover from NG DM
↔ NG DM/PM DMO, NG DM/PM DMO ↔ NG PM, and NG
DM ↔ NG PM.
If violation of limit GW2 persists for duration K.ACC.03,
output is reduced by increment E.LEIST.33. If violation of
this limit continues, rapid changeover to diffusion mode is
initiated after time periods K.BRUMM.10 and K.ACC.03
have elapsed. If the gas turbine is being operated with
water injection at this time, the water injection system is
automatically tripped to prevent extinguishing of the flames.
If violation of GW2 persists for a further time period of
K.BRACC.02, K.BRUMM.10, and K.ACC.03, the fuel oil
system trips.
The reproduction, transmission or use of this document or its
content is not permitted without express written authority.
Offenders will be liable for damages. All rights, including
rights created by patent grant or registration of a utility model
or design, are reserved.
On fuel changeover, limits GW1 and GW2 are
suppressed during the time in which either the natural gas
system or the fuel gas system is being shut down.
No interlocks are provided for GW3, i.e., it is thus
always active.
GW4 is provided for early detection of high acceleration
levels during operation on natural gas near base load.
Gas turbine trip is triggered immediately if GW3 is
violated.
In addition,
measuring
points MBM12CP107,
MBM12CP110, and MBM12CP115 are provided for
detection of combustion chamber humming and are
connected directly to the analysis system. The analysis
system is not part of this system and is therefore not
described in this document.
Monitoring of Burner Temperature
If fuel quality does not meet the standards stipulated by
Siemens (cf. specification “Fuel”), gradual coking may
occur on the FO diffusion burner nozzles and the baffles of
the axial swirler. Such gradual coking changes the shape
and appearance of the flames, this in turn can cause
overheating and ultimately damage to the burners.
Operation on Natural Gas
If violation of limit GW1 persists for duration K.ACC.01,
output is abruptly reduced by the increment E.LEIST.32. If
violation of this limit persists, output is again reduced
repeatedly and abruptly by the same increment each time
K.BRUMM.05 has elapsed.
If fuel oil premix burner supply lines sustain damage,
for example formation of cracks at weld beads or even pipe
fracture, this also causes formation of flames or
overheating in the region of the axial swirler.
If violation of limit GW2 persists for duration K.ACC.02,
output is reduced once by increment E.LEIST.33.
In the standard design, monitoring is not performed in
the operating modes natural gas diffusion, natural gas
premix and fuel oil diffusion.
If violation of limit GW4 persists for duration K.ACC.09,
output is reduced by increment E.LEIST.32.
Flashback is detected using two thermocouples per
burner that monitor burner temperature. Temperature is
measured at the axial swirler.
Natural gas system trip is triggered if violation of the
respective limit GW1 or GW2 persists for the time
K.BRUMM.03 and K.ACC.01 (or K.BRUMM.04 and
K.ACC.02) after the onset of the first output reduction.
Differential temperatures are calculated from the mean
of the compressor outlet temperature and the temperatures
at the axial swirlers. If at least one differential temperature
exceeds TT.BRENNER.M01, the individual alarm
“BURNER TEMPERATURE >MAX” is annunciated.
Class: RESTRICTED
Gas turbine trip is triggered immediately if GW3 is
violated.
Siemens AG
Power Generation
3.1-3000-9080/3
MBM
1204E-X
Gas turbine
Description of Auxiliary Systems
Combustion Chamber
Combustion Chamber Instrumentation
sustains a channel fault the individual alarm “BURNER
TEMPERATURE
MONITORING
FAULTED”
is
annunciated.
If a differential temperature exceeds the setting
TT.BRENNER.U01 for a period of at least 1s during
operation in diffusion mode, startup of the premix burners
is blocked and the alarm “PM BLOCKED” is annunciated.
This interlock is deactivated when the differential
temperature drops below TT.BRENNER.U01.
If both thermocouples of a given burner are defective,
the individual alarm “PM BLOCKED” is annunciated. If this
fault occurs during operation in FO PM, rapid changeover
from FO PM → FO DM is initiated. The machine cannot be
returned to fuel oil premix mode until these channel faults
have been rectified.
Burner Temperature Monitoring in Fuel Oil
Premix Mode
In the event of failure of/faults to one or both
compressor thermocouples, a fixed value is used for
calculating means instead of the defective measurement
(max. value selection).
Ignition System
Flames are ignited electrically. Each burner is equipped
with two ignition electrodes, their tips are located at the
outlet of the NG diffusion burner. Dedicated ignition
transformers (MBM12GT001 to MBM12GT024) supply the
voltage required for ignition to the spark electrodes of the
respective burners. When the ignition voltage is applied, an
arc forms between the tips of the two electrodes.
Failure of Burner Temperature Monitoring
A pretrip alarm is annunciated if individual temperature
measuring points at the axial swirlers fail. This does not
restrict the availability of the machine, however. If
acquisition of one axial swirler temperature measurement
Class: RESTRICTED
The reproduction, transmission or use of this document or its
content is not permitted without express written authority.
Offenders will be liable for damages. All rights, including
rights created by patent grant or registration of a utility model
or design, are reserved.
If one differential temperature exceeds the setting
TT.BRENNER.U01 during operation in FO PM for a period
of at least one second, rapid changeover from FO PM →
FO DM is initiated and the individual alarms “BURNER
TEMPERATURE MONITORING RESPONSE”, “PM
BLOCKED”, and “BURNER INSPECTION NECESSARY”
are annunciated. Changeover back to FO PM is blocked by
an interlock. Continued operation of the GT is permissible
in FO diffusion mode as well as NG diffusion or NG premix
mode.
Siemens AG
Power Generation
3.1-3000-9080/4
MBM
1204E-X
