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Furnace Safeguard Supervisory System Presentation Transcript
1.Furnace Safeguard Supervisory System
2.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.
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.
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
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.F .S.S.S. Equipment can be grouped under three heads
6.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.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.
7.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.
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.
8.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.
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.
9.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
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
10. 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.
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.
11. AIR DAMPER-
12.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.
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.
13. 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.
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.
14.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
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.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
Closure of oil valve,opening of scavenge valve
Igniter advance and sparking
Closure of atomizing valve and scavenge valve
Retract of igniter and gun
16. 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.
The particular corner oil gun engaged feedback is available.
The steam scavenge valve is closed for the particular corner.
17.
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.
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.
18.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.
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.
19.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.
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.
20.Coal elevation logic
Feeder start logic
Pulverizer on
Outlet temperature adequate
Speed demand minimum
No MFT
Feeder stop logic
Had/cad logic
Feeder start logic
Pulverizer on
Outlet temperature adequate
Speed demand minimum
No MFT
Feeder stop logic
Had/cad logic
21. 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
Availability of PA permit
Availability of ignition permit
Seal air /bowl differential pressure
No MFT
Lube oil pressure adequate
Pulverizer stop logic
22. 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.
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.
23.
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:-
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:-
24.
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.
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.
25.
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.
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.
26.FOR B,D,F MILL
27. Flame Scanners
28.MASTER FUEL TRIP (MFT)
29.Unit Logic MFT consequences
30. Trips all mills
Trips all feeders
Trips PA fans
Closes HFO trip valve
Closes all elevation nozzle valves
Close all HAGs
Trips all feeders
Trips PA fans
Closes HFO trip valve
Closes all elevation nozzle valves
Close all HAGs
31. ALL ID FANS OFF
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