1. FSSS (Furnace Safeguard Supervisory System)

2. FURNACE SAFEGUARD SUPERVISORY SYSTEM
F.S.S.S. facilitates remote manual/automatic control of fuel firing equipments through mechanized system and suitable interlocks/logics.
It is designed to ensure the execution of a safe, orderly operating sequence in start up and shutdown of fuel firing equipments and to prevent errors of omission in following such a safe operating procedure.

3. The system provides protection against malfunction of fuel firing equipment and associated air system.
The safety feature of system are designed for protection in most common emergency situations.

4. F .S.S.S. Equipment can be grouped under three heads
The Operating and Indicating Console
This consists of all switches for initiating controls and also indications of status of all fuel firing equipment & their auxiliaries.
2. Relay and Logic Cabinets:
The cabinets consists of relays, timers, programmers, circuit breakers for AC and DC control suppliers flame scanner unit, number of coal flow units etc. They control the process logic

5. Field Equipments
Field equipments are those which help in actual remote operation of fuel firing equipments and those which provide the status to the operating console and relay logic cabinet.
Ignitor/H.O Trip Valves,
H.O atomizing steam,
Scavenging atomizing nozzle valve (Hydramotor type),
Gun advance/retract mechanisms,
Oil gun assembly,
Ignitors and its cabinets,
Flame scanner and ignitor air fans,
Pressure switches, temperature switches, flow switches and limit switches,
Mill Discharge valves, hot air gates, sealing air valves, cold air, tramp iron gate etc.

6. Functions of FSSS
To start complete furnace purge when all technological conditions are fulfilled.
To start and monitor ignitors
H.O. guns, (oil guns) starting, stopping and supervision.
Pulveriser and feeder starting, stopping and supervision
Flame scanner intelligence and checking.
Furnace flame monitoring and overall furnace flame failure protection.

7. Functions of FSSS To start-stop igniter and scanner air fans.
To effect secondary air damper control with indication of auxiliary and fuel air damper modulation/close.
To trip out all boiler fires when boiler safety is threatened
To provide boiler trip signal to other equipments such as P .A. Fan, Turbine, Generator etc.

8. SEC. AIR DAMPER CONTROL SOOT BLOWER CONTROL AUX. PRDS CONTROL
BURNER MANAGEMENT SYSTEM
BOILER PROTECTIONS
MILLING SYSTEM
FUEL OIL SYSTEM
UNIT PURGE
SEC. AIR DAMPER CONTROL
SOOT BLOWER CONTROL
AUX. PRDS CONTROL
HP-BYPASS CONTROL

9. SIMPLIFIED BLOCK DIAGRAM OF BURNER MANAGEMENT SYSTEM.
LOCAL
CONTROL
BOX
FUEL
V/V
DAS
AIR
DAMPER
MILL
CONTROL
FLAME
DETECTOR
IGNITION
CONTROL
PANEL
IGNITER
BOILER
PLANT
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10. FURNACE PURGE Purpose: :
Complete Removal of unburnt fuel from entire furnace
Procedure:
Ensure that all fuel to furnace is cut off and all flame is out
Provide adequate air flow through furnace (30 to 40%)
Initiate a MANDATORY purge time cycle (9 min)
Consequence:
Master Fuel Trip Relays are reset
Firing of fuel into the furnace is allowed
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11. Boiler Purge Logic All HFO nozzle valves are closed
All Pulverizers are off
No MFT condition present
All feeders are off
All scanners sensing no flame.
All auxiliary air dampers modulating
Both PA fans off
All HAGs closed
Air flow more than 30% and less than 50%
HFO trip valve is closed
Wind box to furnace DP is adequate.
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12. A N D PURGE PERMISSIVES All HFO nozzle valves closed
All pulverisers OFF
All feeders OFF
No MFT condition present
All scanners senses no flame TO
FSSS
A N D
All Auxiliary Air dampers modulating
Both PA fans OFF
All Mill HAGs closed
Air flow more than 30% and less than 50%
HFO trip valve is closed
Wind box to furnace DP is adequate
15 April 2017

13. Purge Logic

14. AIR DAMPER- AIR DAMPER ARE DIVIDED AS FOLLOWS-
1-FIVE ELEVATION OF FOUR SECONDARY AIR.
2- 4 ELEVATION OF 4 AIR TO OIL/S.A.D
3-8 ELEVATION OF 4 AIR TO P.F. BURNER.
4-TWO ELEVATION OF FOUR OVERFIRE AIR.
BURNER NOZZLE NOZZLE MILL GROUP
GROUP ELEVATION TYPE GROUP
NUMBER NUMBER
SECONDARY AIR
COAL F
OIL AND S/A
COAL E
SECONDARY AIR
COAL D
OIL AND S/A
COAL C
SECONDARY AIR
COAL B
OIL AND S/A
COAL A
SECONDARY AIR
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PMI Revision 00

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18. Oil Trip Valve operation logic
This logic ensures that oil trip valve can be opened after the purge cycle is completed and no MFT condition is present, if the following conditions are also satisfied.
All nozzle valves are closed.
HFO supply pressure is satisfactory.
HFO header temperature is satisfactory.
Similarly, this logic ensures the closure of oil trip valve in case of MFT.
15 April 2017

19. Oil elevation can be placed in service auto/manual.
OIL ELEVATION LOGIC
There are four heavy oil elevations AB, CD, EF & GH. For all these elevations, logics are same.
Oil elevation can be placed in service auto/manual.
For a particular elevation, only one command is given for all the four corners together. (e.g. One common start command for elevation AB-1, 2, 3 and 4 guns).
Start command goes to corners 1 to 4 sequentially. First command goes to corner 1; after 15 seconds start commend goes to corner 3; again after a lapse of 15 seconds start commend goes to corner 2; and again after a gap of 15 seconds start command goes to corner 4.
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20. 15 April 2017

21. Oil elevation logic Start of oil elevations AB,CD,EF and GH
Sequential operation with start command
Corner1,corner3,corner2 and corner4
Gun advance,igniter advance
Spark,atomizing valve open,oil valve open
Sensing of discriminatory flame
Retract of igniter
15 April 2017

22. Oil elevation logic Stop of oil elevation
Closure of oil valve,opening of scavenge valve
Igniter advance and sparking
Closure of atomizing valve and scavenge valve
Retract of igniter and gun
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23. The particular corner oil gun engaged feedback is available.
A particular corner takes the start command only if the following conditions are satisfied:-
The particular corner oil gun engaged feedback is available.
The steam scavenge valve is closed for the particular corner.
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24. First the oil gun is advanced.
The sequence of operation taking place for a particular oil gun once the command is given is as follows:-
First the oil gun is advanced.
Once gun advanced feedback is available the HEA igniter is advanced.
Then atomizing steam valve is opened for the particular corner.
Then HFO nozzle valve gets open command.
‘Spark’ command is given to igniter transformer, thus producing a spark at the spark tip.
Then for this particular corner ‘HFO flow satisfactory’ feedback comes from the flow switch in the oil line.
The corner oil gun proves when the DISCR FLAME SCANNER senses FLAME.
When 25 seconds elapses after oil valve open, igniter spark signal is removed and spark rod is retracted.
If the corner oil gun did not prove FLAME by this time, ‘Oil nozzle valve’ and atomizing steam valve closes. Gun and igniter are retracted.
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25. 15 April 2017

26. Scanner air fans logic
It monitors the scanner air duct to furnace DP and ensures starting of scanner air fan - A or in case it fails to start, scanner air fan - B. This logic gives an open command to scanner fan outlet damper after starting the fan.
Also, in case of both FD fans not running, it ensures the scanner air emergency damper is open.
15 April 2017

27. Seal air fans logic
Monitors seal air header to cold air duct DP and ensures the starting of seal air fan - A or B ( in case A does not start), provided at least one PA fan is running.
Gives an open command to seal air fan discharge damper once fan starts.
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30. Coal elevation logic Feeder start logic Pulverizer on
Outlet temperature adequate
Speed demand minimum
No MFT
Feeder stop logic
Had/cad logic
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31. Coal elevation logic Pulverizer start logic Availability of PA permit
Availability of ignition permit
Seal air /bowl differential pressure
No MFT
Lube oil pressure adequate
Pulverizer stop logic
15 April 2017

32. COAL ELEVATION LOGIC
PULVERISER LOGIC
This logic takes the count of total no. of pulverisers in service at any point of time, the no. of FD Fans and PA fans in service.
With PA Fan ‘ON’ and PA Header Pressure adequate (>560 mmwcl), it gives “PA permit” to start the Pulverizer.
In case of PA Header Pressure going low-low or PA/ FD fans trips, it ensures the shut down of Pulverizers from top elevation to bottom elevation in a timed sequence.
15 April 2017

33. Each mill can be taken in to service manually or automatically
Each mill can be taken in to service manually or automatically. Auto manual selection push button is available on FSSS console for each mill. Initially, “Pulverizer Ignition Permit” signal must be established for the mill to start. Other condition required to be established for starting the mill are as follows:-
15 April 2017

34. Mill lub oil pressure adequate. Start permit from FSSS.
Mill Discharge valve open.
Mill outlet temp. > 93OC.(200OF)
Cold Air Gate (CAG) open.
Tramp iron vale (Top Reject Gate) open.
Feeder inlet gate open.
Seal air DP adequate (200 mmwcl).
Feeder local switch in remote.
Once the mill is ON, associated HAG can be opened and feeder can be placed in service.
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35. MILL PERMISSIVE: 30% BOILER LOAD AND OR ADJACENT MILL FIRING
PA FAN IN SERVICE
AND OR
INTERMEDIATE OIL BURNER
ELEVATION FIRING
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36. OIL BURNER FIRING ON MILL BEING BROUGHT INTO SERVICE- FOR ANY MILLS(A,B,C,D,E,F,G,H) 1-AT LEAST THREE OIL BURNER S FIRING IN SELECTED ELEVATION. 2- (A) BOILER LOAD > 30% BCMR AND (B) UPPER OR LOWER ADJACENT COAL BURNER IN OPERATION EXAMPLE: FOR MILL A START PERMISSIVE: 1- ELEVATION AB 3/4 OIL BURNER FIRING OR 2- MILL B FIRING AND BOILER LOAD >30% BCMR.
15 April 2017
PMI Revision 00

37. FOR B,D,F MILL (A) AT LEAST 3 OIL BURNERS FIRING IN THE BURNER GROUP ABOVE AND (B) ADJACENT COAL BURNER ABOVE IN OPERATION AND (C) THIS ELEVATION IS HIGHEST IN THE BURNER GROUP. EXAMPLE- FOR MILL B START PERMISSIVE- (1) ELEVATION AB 3 / 4 OIL BURNER ARE I/ S OR (2) MILL A FIRING OR MILL C FIRING AND BOILER LOAD > 30% OF BCMR OR (3) MILL C FIRING AND ELEVATION CD 3 / 4 OIL BURNER ARE I/S. * NOTE THAT B ELEVATION IS HIGHEST IN THE BURNER GROUP AB.
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38. FOR MILL C,E,G (A) AT LEAST 3 OIL BURNER FIRING IN THE BURNER GROUP BELOW AND (B) ADJACENT COAL BURNER BELOW IN OPERATION AND (C) THIS ELEVATION IS LOWEST IN THE BURNER GROUP. EXAMPLE- FOR MILL C START PERMISSIVE – (1) ELEVATION CD 3 / 4 OIL BURNER I/S OR (2) MILL B FIRING OR MILL D FIRING AND LOAD > 30% OF BCMR OR (3) MILL B FIRING AND ELEVATION AB 3 / 4 OIL BURNER ARE I/S. * NOTE THAT C ELEVATION IS LOWEST IN THE BURNER GROUP CD
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39. VOTING OF ELEVATION – VOTING IN AB ELEVATION WILL BE AVAILABLE (1) MILL A FEEDER OR MILL B FEEDER I/S AND ELEVATION AB 2 / 4 FLAMES IN INTRLOCKED WITH ( ALL BURNER IN AB ELEVATION SATISFACTORY S/D OR 3 / 4 OIL BURNER IN THAT ELEVATION ARE I/S.) (2) VOTING IN BC ELEVATION WILL BE AVAILABLE MILL B FEEDER OR MILL C FEEDER I/S AND ELEVATION B 2 / 4 FLAMES IN. VOTING WIL NOT BE AVAILABLE – (1) BOTH FEEDERS ON BURNER ELEVATION ARE NOT I/S OR (2) 2/4 FLAME ARE NOT SENSED INTERLOCKED WITH 3 / 4 OIL BURNER ARE NOT FIRING OR (3) OIL GUN IN THAT ELEVATION NOT SATISFACTORLY SHUTDOWN INTROLOCKED WITH 3 / 4 OIL BURNER IN THAT ELEVATION NOT FIRING.
Flame Scanners
15 April 2017

40. Scanners

41. MASTER FUEL TRIP (MFT) MFT or Boiler Trip means:
Complete isolation of all fuel to furnace under certain conditions
Automatic Procedure:
All oil valves are given closing command
All mills and feeders are given trip command
All Primary Air (PA) Fans are given trip command
All Hot Air Gates (to mills) are given closing command
Further Consequences:
Turbine protection is initiated (to trip turbine)
All SH and RH spray valves are given closing command
All elevation SADC are given full open command
Furnace pressure & Air flow controls are set to manual
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42. Unit Logic MFT consequences
Trips all mills
Trips all feeders
Trips PA fans
Closes HFO trip valve
Closes all elevation nozzle valves
Close all HAGs
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43. 15 April 2017
PMI Revision 00

44. O R Both FD fans OFF Both ID fans OFF
Inadequate water wall circulation for more than 5 seconds
Loss of Reheat Protection for greater than 10 seconds
All BFPs tripped
Drum level very high for more than 10 seconds (2/3 logic)
Drum level very low for more than 10 seconds (2/3 logic)
Furnace pressure very high (2/3 logic)
Furnace pressure very low (2/3 logic)
MFT
RELAY
O R
Loss of all fuel
All feeders OFF and loss of AC Supply to the elevation in service
Unit flame failure
Loss of Unit Critical Power for more than 2 seconds
Both Secondary APHs OFF
Loss of 220 V DC Supply for more than 2 seconds
Manual Emergency PB trip
Air flow less than 30% and boiler load not greater than 30%
15 April 2017

45. Reheater Protection

46. Reheater Protection Arming

47. THANK YOU …
QUESTIONS ?
15 April 2017