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FSSS (Furnace Safeguard Supervisory System)

FSSS (Furnace Safeguard Supervisory System). www.powerpointpresentationon.blogspot.com. FURNACE SAFEGUARD SUPERVISORY SYSTEM. F.S.S.S. facilitates remote manual/automatic control of fuel firing equipments through mechanized system and suitable interlocks/logics.

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FSSS (Furnace Safeguard Supervisory System)

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  1. FSSS(Furnace Safeguard Supervisory System) www.powerpointpresentationon.blogspot.com

  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. 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. B M S LOCAL CONTROL BOX FUEL V/V DAS AIR DAMPER MILL CONTROL FLAME DETECTOR IGNITION CONTROL PANEL IGNITER BOILER PLANT

  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

  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.

  12. 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

  13. Purge Logic

  14. BURNER NOZZLE NOZZLE MILL GROUP GROUP ELEVATION TYPE GROUP NUMBER NUMBER 4 13---------------------------SECONDARY AIR 12---------------------------COAL--------------------------- -F 11---------------------------OIL AND S/A 3 10 --------------------------COAL-----------------------------E 9 --------------------------SECONDARY AIR 8---------------------------COAL------------------------------D 2 7-------------------------- OIL AND S/A 6---------------------------COAL------------------------------C 5---------------------------SECONDARY AIR 4---------------------------COAL------------------------------B 1 3---------------------------OIL AND S/A 2---------------------------COAL------------------------------A 1-------------------------- SECONDARY AIR 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.

  15. PMI Revision 00

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  21. 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.

  22. 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.

  23. 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.

  24. Coal elevation logic Feeder start logic • Pulverizer on • Outlet temperature adequate • Speed demand minimum • No MFT • Feeder stop logic • Had/cad logic

  25. 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

  26. 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.

  27. 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:-

  28. 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.

  29. 30% BOILER LOAD AND ADJACENT MILL FIRING AND PA FAN IN SERVICE MILL PERMISSIVE: OR INTERMEDIATE OIL BURNER ELEVATION FIRING

  30. 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% BCMRAND (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. PMI Revision 00

  31. FOR B,D,F MILL(A) AT LEAST 3 OIL BURNERS FIRING IN THE BURNER GROUP ABOVE AND(B) ADJACENT COAL BURNER ABOVE IN OPERATIONAND(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 FIRINGAND 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.

  32. 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

  33. 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

  34. Scanners

  35. 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

  36. Unit LogicMFT consequences • Trips all mills • Trips all feeders • Trips PA fans • Closes HFO trip valve • Closes all elevation nozzle valves • Close all HAGs

  37. PMI Revision 00

  38. 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%

  39. Reheater Protection

  40. Reheater Protection Arming

  41. THANK YOU … QUESTIONS ?

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