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Start up system and
seperator logics 660MW
(DHI make) boiler
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BOILER START-UP AND
OPERATIONAL PROCEDURES
Cold Start Up conditions Greater than 72 hours shutdown.
Boiler pressure < 1 kg/cm2 (g)
Preparation for BLU Chemical cleaning and steam blowing completion (for
the first time)
All interlocks and protections in service All instrumentation and associated mechanicalequipment has been checked out and is available forservice.
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Oil firing equipment checked out to ensureproper functioning
Warm-up oil guns have been inserted properly andcoupled.
All oil guns quick connect couplings are properlyassembled.
All manual valves are opened.
All control valves are closed.
Pulverisers and feeders are available forservice
SADC checking complete & burner tilthorizontal
Feedwater system is through and atleast onefeed water pump available.
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The deaerator aux. steam supply is available
and feedwater in deaerator is at 105C.
BCP checked out completely Suction and discharge iso. Valves open
All pump instrumentation available in service
Pump diff. pressure transmitters in service
Ensure proper trip settings have been made
The steam generator start-up system valves
are ready for operation (UG, WR, ZR valves),
with isolation valves open. The separator levelcontrol for WR and ZR valves has been
checked and is available for service.
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The startup system drain transfer system is ready for
operation. This system includes WR and ZR valves,
the flash tank and connecting pipe to condenser.
Steam supply isolating valves to the steam coil air
pre-heaters are open.
Cooling water system is in operation
All air and gas handling equipment has been checked
and is available for service.
Air heater ready for service & means for extinguishing
APH fire is available.
The soot blowing equipment has been checked for
proper operation and the system is in the start-up
mode with all blowers retracted and the main steam
supply valve closed.
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All desuperheater spray water control and blockvalves valves are closed.
All boiler, superheater, and reheater drain valves areopen, and all vent valves are closed. The economizerand furnace wall drain valves are closed, andeconomizer vent valves are open.
The aux. steam isolation line from the superheater is
isolated. The warming system of the boiler superheaters is
isolated.
The furnace gas temperature probe(s) is in workingorder and available for service.
The HP and LP bypass stations are available forservice, and hydraulic stations are in operation. Thewater supply for desuperheating has beenestablished.
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The condenser is available in service, with circulationwater flow and vacuum has been established toaccept water flow from Start-up flash tank and theSCAPH drain tank and LP bypass (condenserpressure set point interlock of LP bypass).
The main steam stop cum control valves and the hotreheat stop and control valves are closed. Drainvalves on the main, cold reheat and hot reheat linesare open.
The condensate polishing plant is available foroperation.
The TG has been prepared and is available forservice
Warm water filling The entire economizer, furnace wall and seperator
system should be filled with warm deaerated water(105C)
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The following procedure shall be carried out to ensurethat the water system is free of air :-
The economiser outlet vent valve is open.
BFP (M) is started at minimum speed and flow according tofeed pump operating procedures.
Water system is to be filled with approx. 10 % BMCRfeedwater flow. When level in the seperator reaches set-pt.,the WR valve will begin to open. When the WR valve reaches
> 30% open for approx. 1 min., feedwater flow set pt. isincreased to 30 % TMCR. As the drain flow increases, WRvalve will reach full open and ZR valve will begin to open.The water system is considered full when :-
The seperator water level remains stable for two minutes.
And The WR valve is fully opened and ZR valve is >15 %
opened for two (2) minutes. After filling of water system, the feedwater pump is stopped.
Water level in deaerator must be re-established andmaintained and water temperature at 105C is reestablished.
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Restart the feed water pump and establish feedwater flow of
10 % BMCR to the boiler.
Water recirculation for clean up
Feed water clean up recirculation is required to
ensure that feedwater quality at the o/l. of seperator
and deaerator is within specified limits.
During this time, a constant feedwater flow of 10 %
BMCR is maintained.
Feed water flows through
Ecomomiser and Evaporator and discharges the boiler
through the WR valve to the flash tank and via connecting
pipe to the condenser. From condenser, water flows through
the CPP, which is in service to remove impurities,then
returns to the feedwater tank.
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Start of Boiler Circulation Pump The following preparatory work needs to be completed :-
Feed water quality within specified limits.
Feed water flow set point at 10% BMCR.
Seperator water level stable at normal level. Cooling water flow to the HP cooler of BCP adequate.
Suction valves and discharge valves are open.
Set the UG valve at min. position and start BCP as per pumpoperating instructions.
As soon as pump is running, open the UG valve to establish min.
water wall flow at 30% TMCR. With BCP in operation, flow through the economiser and water
wall tubes increases substantially.
Initial firing precautions
Atleast 30% of the TMCR load air flow must be maintained toproduce the following conditions :- An air rich atmosphere to prevent accumulation of an explosive
mixture
High excess air through the APHs
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Boiler Light Up Start the Secondary Air Preheater
Start one ID fan, then the corresponding FD fan andadjust air flow to a max. of 30% TMCR
Start the second draft group
Start the selected scanner air fan.
Adjust fan and SADC to permit a purge air flow of
atleast 30% of TMCR and furnace draft of approx. -12.7 mmWC.
When fans are started, SADC should modulate theaux. air dampers to maintain WB to furnace DP at 102
mmWC(g). Check that all other purge permissives are satisfied.
Place FTPs in service.
Initiate a furnace purge.
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After furnace purge check the followingconditions
FW control is on auto maintaining FW flow rate ofapprox. 5% TMCR.
Start-up system (BCP and UG valve) is onautomatic maintaining minimum waterwall flow.
Seperator level control is on auto, i.e the WR and
ZR level control valves are all in automatic. Furnace pressure control is on auto.
Unit air flow is on auto maintaining 30% TMCR airflow.
Place HP bypass valve in operation Place LP bypass valve in operation
Place SH and RH temp. controls on auto. Withsetpoints of 350 C for SH and 320 C for RH.
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Open SH division panel vent valves, SH backpassdrain valves and RH outlet vent valves.
Initiate a light-up sequence of oil elevation AB warm-up oil guns.
Set fuel oil flow control to auto and adjust the TMCRto 5 % of TMCR firing rate.
When elevation AB is in service, close theeconomizer vent valves.
After a 5 minute stabilization period, progressivelyincrease firing rate to 10 % TMCR at a rate of 0.5%per minute.
To ensure stable operation of the water system and toensure sufficient steam flow through the superheater,firing rate shouldnot be further increased until 8kg/cm2 (g) is measured in the water seperator.
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As the pressure is raised, first the WR and then the
ZR valves will open when seperator water level
increases due to boiler water swell. As the pressure
further increases,the WR and ZR valves will start toclose as the water level decreases.
During all start-ups, control the firing rate to keep the
max. FEGT below 538 C, as measured by the
furnace temperature probes until approx. 10% steamgeneration or the turbine is synchronized.
The superheat backpass drain valve can be closed
when seperator pressure reaches 5 kg/cm2 (g).
Progressively increase LP bypass set point to 12kg/cm2(g).
Close the RH o/l. vent valves when RH pressure
reaches 5 kg/cm2.
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Increase LP bypass set pt. to 12 kg/cm2(g). As theHP bypass opens, the reheater will be warmed andpressurized cas steam is passed through the LPbypass and reheater vents.
Close the reheat outlet vent valves when RH pressurereaches 5 kg/cm2(g).
When steam pressure at HP bypass reaches 12kg/cm2(g), the HP bypass valve is released topressure ramp mode
Initiate an elevation start command for other oilelevations.
After a 5 minute stabilization period, progressivelyincrease firing rate to 15% TMCR at a rat of 0.5% perminute.
The rate of pressure rise should follow the prescribedstart up curves
When boiler pressure reaches 90 kg/cm2(A), the HPbypass valve is released to pressure control modeand maintains a constant pressure during rolling.
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After a pressure of 90 kg/cm2 is attained the firingrate can be adjusted to achieve the reqd. steamtemperature for turbine rolling. Target steamconditions are:- 10% TMCR steam flow, SH = 350 C,RH = 320 C.
Maintain seperator water level at normal and checkthe boiler water concentrations and constituents asfrequently as necessary to maintain proper boilerwater conditions.
Turbine rolling and synchronisation Confirm the steam conditions, i.e. pressure,
temperature
Roll turbine using reheat steam. During this time totalsteam passes through HP bypass while it remains onpressure control mode.
SH and RH steam temperatures are maintained byadjusting firing rate and air flow.
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Synchronize generator and put on initial load of app.10% according to TG start up instructions.
After synchronization, all superheat and reheat vent
and drain valves should be closed. As steam is transferred to the IP turbine during
turbine loading, the LP bypass will close whilemaintaining reheat pressure at 12 kg/cm2.
Increase firing rate to 20 % TMCR at a rate of 0.5%per minute.
As turbine conditions permit, put feed water heatersinto service as per manufacturers instructions.
The firing rate should never exceed the rate
necessary to match the total steam generation. If the unit was started with one set of fans in service,
start the second set of fans as required.
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Introduction of coal Coal firing can commence when steam flow reaches
approximately 20% TMCR and LP bypass is closed.
Start the first pulverizer At a prescribed load as per turbine manufacturer, the
HP turbine is transferred to forward flow. At first threeturbine control valves are opened until sufficient flowis established through the HP section of the turbine.
The HP bypass valve compensates by closing tocontrol the steam pressure at set point.
Continue the transfer to forward flow until the firstthree turbine valves are fully opened and HP bypassvalves are fully closed.
Start the second pulverizer when the HP bypass isclosed.
Increase the total firing rate to 30% TMCR at a rate of0.5% per minute by increasing each coal elevationloading.
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Initial load increase The third pulverizer can be started after steam flow
reaches 25-30% TMCR. Place additional pulverizers
in service in a similar manner. Pre-warm thepulverizer initiate an elevation start command. Afterthe coal elevation is proven in service the feeder isput into automatic.
Increase total firing rate to 35% TMCR.
After reaching 30% TMCR load and firing is stable, oilelevation AB is issued an elevation stop command bythe operator
After oil elevation AB is stopped ensure that coal el. Aor C shows flame through flame scanner indications.
Reduce oil firing to minimum After stable firing is established, put into service the
second BFP(T) as per manufacturers procedures.
Start the ESP as per manufacturers instructions.
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The steam temperature at the seperator inlet will
reach a stable superheated condition at
approximately 30% TMCR, causing the level in the
seperator to decrease and eventually disappear. The
boiler is now in once-through mode (dry mode). The
BCP will be stopped automatically.
When the BCP stops, the warm-keeping system of
the start-up system should be put into operation.
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Wet mode and Dry mode of operation
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Operational Logics for Mixing Piece Upstream
Valve orBCP circ. Shut-off MOV
Open permissive If WET mode of operation is selected AND
DRY mode is not selected
Close permissive
BCP off Auto opening
Open permissives present AND any of the following conditionsare present
MFT has operated OR
Open command from start sequence for BCP circ. Shut off valve(Mixing piece upstream valve) OR
System in wet mode of operation for 3 seconds
Auto closing If system is in dry mode of operation for 3 seconds.
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Operational logics for Boiler
recirculation Pump
Start permissive UG valve opening > min. (15 %)AND
BCP circ. Shutoff MOV openedAND
BCP inlet shut off MOV openedAND
BCP outlet shut off MOV openedAND
BCP inlet manual valve openedAND
BCP cooling water flow not lowAND
Seperator storage tank level > 1100 mm AND
Economiser inlet flow > 111 T/hrAND
No BCP trip override existsAND
No BCP MCC disturbance exists
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Trip permissives
Dry mode of operation of the boiler
Auto starting of BCP
BCP will get auto started if either BCP auto
start signal is present OR
Start BCP FR. W & steam start seq. signalfrom Start seq. is present.
BCP auto Start signal
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Auto stopping of BCP
BCP will stop on auto if either BCP auto stop
signal OR BCP MCC disturbance signal ispresent.
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BCP trip override logic
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Operational logics for BCP Inlet
Shut-off MOV Open permissive
If WET mode of operation is selected OR
BCP not tripped
Close permissive
BCP not running (stopped) Auto opening
Open permissives presentAND any of the following conditionsare present
MFT has operated OR
Open command from start sequence for BCP inlet shut off MOV OR System in wet mode of operation for 3 seconds OR
BCP auto start signal is present
Auto closing BCP trip signal
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Operational logics forBCP Outlet
Shut-off MOV Open permissive
If WET mode of operation is selected OR
BCP not tripped
Close permissive
BCP not running (stopped) Auto opening
Open permissives presentAND any of the following conditionsare present
MFT has operated OR
Open command from start sequence for BCP outlet shut off MOVOR
System in wet mode of operation for 3 seconds OR
BCP auto start signal is present
Auto closing
BCP trip signal
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Operational logics forBCP
Circulation Line Vent MOV Open permissive
If Auto Dry Mode of operation is not selectedAND
If BLI is less than 15 % BMCR OR BCP is notrunning
Auto opening Open permissives present and also if any of thefollowing conditions are present
MFT has operated OR
Open command from start sequence for BCP circ. Line ventMOV OR
BCP is not running
Auto closing If Auto Dry Mode of operation is selected OR
If BLI > 15 % BMCR and BCP running (proven for 20
secs.
Operational logics for WR Line
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Operational logics for WR Line
Isolation MOV Open permissive
If BLI is lesser than 1000 T/hrAND Either Main steam bottle up OFF OR
All feedwater pumps not off.
Close permissive BLI > 960 T/hrOR
If all FW pumps are offAND BCP is offAND all scanners show no flame
Auto opening Open permissives presentAND also if any of the following conditions are present MFT has operated OR
Open command from start sequence for WR line isolation MOV OR
Auto wet mode of operation OR
Seperator storage tank level > 1100 mm OR
BLI < 890 T/hr.
Auto closing BLI >1000 T/hrOR Main steam bottle up ONAND All feedwater pumps off
Manual close After manual control is enabled, this will take place
If Manual close command is sent from LVS / OWSAND
Seperator storage tank level is not greater than 1100 mm.
Operational logics for ZR Line
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Operational logics for ZR Line
Isolation MOV Open permissive
If BLI is lesser than 1000 T/hrAND Either Main steam bottle up OFF OR
All feedwater pumps not off.
Close permissive BLI > 960 T/hr OR
If all FW pumps are offAND BCP is offAND all scanners show no flame
Auto opening Open permissives presentAND also if any of the following conditions are present MFT has operated OR
Open command from start sequence for ZR line isolation MOV OR
Auto wet mode of operation OR
Seperator storage tank level > 1100 mm OR
BLI < 890 T/hr.
Auto closing BLI >1000 T/hrOR Main steam bottle up ON AND All feedwater pumps off
Manual close After manual control is enabled, this will take place
If Manual close command is sent from LVS / OWSAND
Seperator storage tank level is not greater than 1100 mm.
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Operational logics forStorage tank drain MOV /
Seperator water leg level control blocking MOV
Open permissive
Dry mode of operation
Auto opening
If seperator water leg control valve demand > 5 %.
Auto closing
Close seperator water leg CV demand from Start
sequence. OR
MFT operated OR
BCP on and Wet mode of operation OR
Seperator water leg CV demand < 2%AND
Close position < 5 %.
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Operational logics for Start up
system warming MOV
Open permissive Dry mode of operation
Auto opening
Open permissives presentAND also if any of thefollowing conditions are present Seperator storage tank level is less than 4000 mm
Auto closing If wet mode of operation OR
If MFT gets operated OR
Close start up system warming valve command ispresent from Start up sequence. OR
Seperator storage tank level > 1100 mmAND BCP
On.
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Operational logics for BCP Drain
MOV
Open permissive
BCP not running
Auto closing
BCP running
Operational logics for BCP outlet
drain MOV Open permissive BCP not running
Auto closing
BCP runnin
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Separator logic (Seperator storage tank wet leg level)
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Separator logic (Seperator storage tank wet leg level)
Separator logic (Seperator storage tank level)
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Separator logic (Seperator storage tank level)
Separator logic (Control of flow through BCP)
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Separator logic (Control of flow through BCP)
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