Mill Burner Control

Ensure that a furnace purge cycle has been completed prior to firing any fuel.Prevent start-up of individual fuel firing equipment unless certain permissive interlocks have first been satisfied.Monitor and control the proper component sequence during start-up and shutdown of fuel firing equipment.Ensure that certain safety interlocks remain satisfied during operation of fuel firing equipment.Provide component status feedback to the operator, the unit control system and the data logger.Initiate a fuel trip when certain abnormal operating conditions exist.

PURGE PERMISSIVES 1. POST TRIP PURGE CYCLE 2. FURNACE PURGE CYCLELOTV/HOTV (OPEN/CLOSE )INTERLOCKSHORV OPEN/CLOSE INTERLOCKSOIL GUNS START/STOP CYCLEBOILER PROTECTION LOGICSPA FAN INTERLOCKS COVERED UNDER FSSSCOAL MILL START/STOP INTERLOCKSCOAL FEEDER START/STOP INTERLOCKSSCANNER AIR FANSSEAL AIR FANSSADC AND OTHER DAMPER INTERLOCKSMILL LUB OIL SYSTEM INTERLOCKS

MFT Light oil trip valve closed Heavy oil trip valve closed All oil valves closed All pulverizer offAll feeders off Air flow > 30% BMCR All flame scanners no flame All PA Fans off

FURNACE PURGE PERMISSIVES1. No boiler trip conditions exists.2. All MBC System power available3. Unit air flow > 30% BMCR4. Nozzle tilts horizontal and air flow < 40% BMCR.5. Both primary air fans are off.6. The oil trip valve (HFO and LDO) is closed.7. The oil nozzle valves (HFO and LDO) in all elevations are closed. 8. All pulverizers are off.9. All feeders are off.10. All Hot air gates of pulverizers are closed.11. All flame scanners on all scanner elevations indicate no flame.12. The auxiliary air dampers at all elevations are modulating

HOTV OPEN PERMISSIVES1. No MFT2. All elevation oil nozzle valves remain closed.3.Recirculation Valve open4. Open push button pressedOIL ELEVATION START-PERMIT1. HFO header pressure not low.2. Atomizing steam pressure not low.3. No master fuel trip signal exists4. All feedwater pumps not off and economizer inlet flow not low.5. Nozzle tilts horizontal and air-flow less than 40% BMCR.HOTV PROTECTION CLOSINGHOTV is not closed and any warm-up nozzle valve is not closed and the HFO header pr is very low or Atomising Steam Pressure is very low2. MFT Signal Established

LDO TRIP VALVE OPEN PERMISSIVES1. No MFT2. Elevation AB oil nozzle valves remain closed.3. Light oil return valve is open4. Open push button pressedOIL ELEVATION START-PERMIT1. LDO header pressure not low.2. Atomizing air pressure not low.3. No master fuel trip signal exists4. All feedwater pumps not off and economizer inlet flow not low.5. Nozzle tilts horizontal and air-flow less than 40% BMCR.LDO TRIP VALVE PROTECTION CLOSINGLDO TRIP VALVE IS NOT CLOSED AND ANY LDO NOZZLE VALVE IS NOT CLOSED AND THE LDO HEADER PR IS VERY LOW OR ATOMISING AIRPRESSURE IS VERY LOW2. MFT SIGNAL ESTABLISHED

WARM UP OIL ELEVATION START PERMIT FULFILLEDTHREE MODE OPERATION OF OIL GUNS (PAIR,CORNER,ELEVATION)IN ELEVATION MODE FIRST CORNER-1 IS PLACED INTO SERVICE, CORNERS 3, 2 AND 4 ARE PLACED IN SERVICE SEQUENTIALLY AT 15 SECOND INTERVALS.CONDITIONS FOR PLACING A CORNER INTO SERVICE1. OIL GUN IS ENGAGED2. MANUAL ATOMISING AIR/STEAM VALVE AND MANUAL HFO/LDO VALVE OPEN3. ASSOCIATED CORNER DISCRIMINATING SCANNER SHOW NO FLAME

CORNER SEQUENCEThe oil gun receives an advance signal.The high energy arc (HEA) igniter receives an advance signal.When the HEA igniter is advanced, the oil gun valves open to firing position signal is established and a thirty (30) second ignition trial period is started.When the oil gun valve is moved from the closed to firing position, the HEA ignitors spark signal is established.When the thirty (30) second counting period expires the HEA ignitors spark signal is removed and the HEA ignitors spark rod is retracted. If the flame scanner indicates flame, the oil gun will remain in service.

All four corners are removed from service in the same manner starting with Corner 1. Corners 3, 2 and 4 are removed from service sequentially at thirty (30) second intervals.CORNER SHUT-DOWN1. Oil valve closes.2. Igniter spark on.3. Atomizing and scavenging valve are open.4. When the scavenge valve is open, a 300 second scavenge counting period is started.5. After 300 seconds igniter retracts6. Oil gun retracts

When the elevation stop 400 second counting period expires, a fifteen second counting period is begins, and the following events occur:400 second counting period is for monitoring of shut down of all the four cornerAfter 15 sec counting period if HEA igniters are not retracted then unsuccessful spark rod shut down alarm will comeelevation unsuccessful shut down alarm isActivated if Any oil valve is not closed on the associated oil elevation.ORAny oil gun is not retracted on the associated oil elevation.

The oil gun becomes not engaged or not advanced.The associated corner local control station's selector switch is moved from the REMOTE position to the OFF position.The associate corner oil manual valve not open.The manual air atomizing valve for LDO firing is not open.The manual steam atomizing valve for HFO firing is not openThe oil elevation trip signal exists when any of the following conditions are established.Header oil trip valve (LOTV, HOTV) not open.Master Fuel Trip.

BOILER PROTECTION1. Both ID fans are off.2. Both FD fans are off.3. Unit air flow < 25% TMCR.4. All feedwater pumps are off for more than fourteen seconds.5. At least two of three furnace pressure transmitters indicate the furnace pressure is high for more than eight seconds.At least two of three furnace pressure transmitters indicate the furnace pressure is highhigh.7. At least two of three furnace pressure transmitters indicate the furnace pressure is low.8. Loss of Reheat Protection.9. Both EMERGENCY TRIP (hard) push buttons are depressed simultaneously or the MFT (soft) push button is activated.10. Economizer inlet flow low for more than ten seconds.

BOILER PROTECTION CONTINUED11. Furnace vertical wall tube temperature high12. Superheater pressure (both leads) high.13. Superheater temperature (either side) high for more than twenty seconds.14. Reheater outlet (either side) temperature high for more than twenty seconds.15. Separator level low low at the wet mode16. Separator level high high at the wet mode17. MBC Supply OFF.18. Loss of fuel trip.19. Unit flame failure trip20. Boiler Trips if Turbine trips on Low Vacuum.

LOSS OF ALL FUEL TRIP PROTECTIONARMINGA loss of fuel trip arming memory signal is established when any oil valve is open.Protection will act whenAll feeders are off.The Heavy oil trip valve is not open or all heavy oil nozzle valves are closed.The light oil trip valve is not open or all light oil nozzle valves are closed.

REHEATER PROTECTIONARMINGTotal fuel flow > X % (where X corresponds to 538 C furnace flue gas temperature) ORSteam flow > X % or measured furnace temperature > 538 C. Protection will act when (10 sec time delay)A loss of main steam flow path (no path through HP turbine or HP bypass, or no flow path through LP turbine or LP bypass).The boiler remains in an over fired condition (total fuel 5% above steam flow) 50 seconds after a turbine trip or fast cutback.HPBP & LPBP not open after generator tripped.HPBP & LPBP not open after turbine tripped. HPBP not open after HPSV/CV closed or LPBP not open after IPSV/CV closed.

UNIT FLAME FAILURE PROTECTIONARMINGAny feeder provenPROTECTION WILL ACT WHENAll eleven scanner elevation indicate flame failureELEVATION AAFeeder A is off with 2 sec time delayORLess than 2/4 scanner show flame on elevation AA

FLAME FAILURE PROTECTIONELEVATION-AFeeder A and Feeder B are off with two seconds time delay.ORAny oil valves not closed on elevation AB AND Three out of four oil valves not proven on Elevation ABANDLess than two out of four scanners show flame on Elevation AORLess than two out of four scanners show flame on Elevation A AND Two out of four oil valves not open on Elevation AB

FLAME FAILURE PROTECTIONELEVATION BFeeder B and Feeder C are off with two seconds time delay.ORLess than 2/4 scanner show flame on elevation B

FLAME FAILURE PROTECTIONELEVATION-CFeeder C and Feeder D are off with two seconds time delay.ORAny oil valves not closed on elevation CD AND Three out of four oil valves not proven on Elevation CDANDLess than two out of four scanners show flame on Elevation CORLess than two out of four scanners show flame on Elevation C AND Two out of four oil valves not open on Elevation CD

FLAME FAILURE PROTECTIONELEVATION DFeeder D and Feeder E are off with two seconds time delay.ORLess than 2/4 scanner show flame on elevation D

FLAME FAILURE PROTECTIONELEVATION-EFeeder E and Feeder F are off with two seconds time delay.ORAny oil valves not closed on elevation EF AND Three out of four oil valves not proven on Elevation EFANDLess than two out of four scanners show flame on Elevation EORLess than two out of four scanners show flame on Elevation E AND Two out of four oil valves not open on Elevation EF

FLAME FAILURE PROTECTIONELEVATION F, H, G, JElevation F, H are the same as Elevation D.Elevation G, J are the same as Elevation E

FLAME FAILURE PROTECTIONELEVATION KFeeder K is off with 2 sec time delayORLess than 2/4 scanner show flame on elevation K

MASTER FUEL TRIP1. The header oil trip valves for HFO and LDO are closed.

2. All corner oil valves are closed.3. All pulverizers and feeders are shut down.4. All pulverizer gates and dampers are closed.5. The primary air fans are tripped.

6. The fuel and auxiliary air dampers are opened and the auxiliary air dampers control is transferred to manual.

7. The feed forward to furnace draft control signal is established for thirty seconds and is then removed.

PULVERIZER MANUAL STARTThe pulverizer ignition permit condition is satisfied.The pulverizer ready condition is established.No pulverizer trip condition exists . The manual mode of operation has been selected.

PULVERIZER IGNITION PERMITPULVERIZER A IGNITION PERMITElevation AB oil is proven in service (three out of four oil valves are open ).ORFeeder B is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

PULVERIZER B IGNITION PERMIT

Elevation AB oil is proven in service (three out of four oil valves are open ).ORFeeder A is proven (feeder is on for at least fifty seconds) and its feeder speed is greater than 50% and boiler load is greater than 30% TMCR.ORFeeder C is proven (feeder is on for at least fifty seconds) and its feeder speed is greater than 50% and boiler load is greater than 30% TMCR.ORFeeder C is proven (feeder is on for at least fifty seconds) and its feeder speed is greater than 50% and Elevation CD oil is proven in service (three out of four oil valves are open ).

PULVERIZER C IGNITION PERMIT

Elevation CD oil is proven in service (three out of four oil valves are open ).ORFeeder D is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder B is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder B is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and Elevation AB oil is proven in service (three out of four oil valves are open ).

PULVERIZER D IGNITION PERMIT

Elevation CD oil is proven in service (three out of four oil valves are open ).

ORFeeder C is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.ORFeeder E is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.ORFeeder E is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and Elevation EF oil is proven in service (three out of four oilvalves are open ).

PULVERIZER E IGNITION PERMIT

Elevation EF oil is proven in service (three out of four oil valves are open ).ORFeeder F is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder D is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder D is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and Elevation CD oil is proven in service (three out of four oilvalves are open ).

PULVERIZER F IGNITION PERMIT

Elevation EF oil is proven in service (three out of four oil valves are open ).OR Feeder E is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder G is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder G is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and Elevation GH oil is proven in service (three out of four oilvalves are open ).

PULVERIZER G IGNITION PERMIT

Elevation GH oil is proven in service (three out of four oil valves are open ).ORFeeder F is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.ORFeeder H is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder F is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and Elevation EF oil is proven in service (three out of four oilvalves are open ).

PULVERIZER H IGNITION PERMIT

Elevation GH oil is proven in service (three out of four oil valves are open and ).

ORFeeder G is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder J is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

ORFeeder J is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and Elevation JK oil is proven in service (three out of four oilvalves are open ).

PULVERIZER J IGNITION PERMIT

Elevation JK oil is proven in service (three out of four oil valves are open ).OR Feeder H is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.ORFeeder K is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.ORFeeder H is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and Elevation GH oil is proven in service (three out of four oilvalves are open ).

PULVERIZER K IGNITION PERMIT

Elevation JK oil is proven in service (three out of four oil valves are open ).

ORFeeder J is proven (feeder is on for at least fifty seconds) and its feeder speed isgreater than 50% and boiler load is greater than 30% TMCR.

PULVERIZER READY CONDITION1. THE PULVERIZER START PERMITNo Master Fuel Trip exists.ANDFuel nozzle tilts are horizontal and air flow through the unit is less than 40% TMCR air flow. (feeder is on for at least 50 seconds).

ORAny feeder is proven to be a feeder load more than 50% rate of feeder capacity (feeder is on for at least 50 seconds).

PULVERIZER READY CONDITION (CONTINUED)

The pulverizer discharge valve is open The pulverizer outlet temperature is less than 95CThe pulverizer air gates (cold and hot) are open.The bunker outlet gate is open.No unsuccessful start sequence in the automatic mode. The gates to the Pyrite removal system are open.The feeder local control switch is in the remote position.All coal burner shut-off gates open.No pulverizer tripLube system start permit.

LUBE SYSTEM START PERMITThe lube oil pump must be proven onThe oil supply pressure must be proven adequate after 3 minutes.The oil supply temperature must be adequate, (greater than 35C).The lube oil supply flow must be adequate.The oil filter must be clean, differential pressure not high with the oil pump proven ON and oil supply temperature greater than 40C.

PULVERIZER TRIP CONDITIONSMFTAny pulverizer discharge valve is not fully open.Seal air header to pulverizer under bowl differential pressure low for more than ten seconds.Respective coal feeder tripPulverizer ignition permissive and warm-up oil support lost during the three minute flame stabilization period when the feeder is started.

PULVERIZER TRIP CONDITIONSLUBE OIL SYSTEM TRIP CONDITION.The lube oil supply pressure is inadequate for more than 2 seconds 25 seconds after the lube oil pump is proven on. Any one of the four pulverizer thrust bearing temperatures is high, greater than 80 C.The lube oil supply temperature becomes excessive, greater than 65 C.The lube oil tank temperature is inadequate, less than 30C.The lube oil tank level is not adequate.

PULVERIZER TRIP CONDITIONS (CONTINUED)A LOSS OF PRIMARY AIRThe primary air duct to furnace differential pressure is low for more than five seconds.The primary air duct to furnace differential pressure is low/low.Either primary air fans are not on and any pulverizer is on.

PULVERIZER TRIP CONDITIONS (CONTINUED)LOSS OF PA FAN TRIP CONDITION Seven or more pulverizers are on AND Either primary air fan is not on then a sequence of pulverizer trips will get initiated (affecting only, E,F,G,H,J and K pulverizers) until less than seven pulverizers are on. Pulverizer K receives a trip command.Two seconds later, pulverizer J receives a trip command.If Pulverizer K stop, Pulverizer J will be stopped without time delayFour seconds later, pulverizer H receives a trip command. If Pulverizer J stop, Pulverizer H will be stopped after Two seconds time delayFour seconds later, pulverizer H receives a trip command. If Pulverizer J stop, Pulverizer H will be stopped after Two seconds time delaySix seconds later, pulverizer G receives a trip command.If Pulverizer K, J, H stop, Pulverizer G will be stopped without time delayEight seconds later, pulverizer F receives a trip command. If Pulverizer K, J, H, G stop, Pulverizer F will be stopped without time delayTen seconds later, pulverizer E receives a trip command. If Pulverizer K, J, H, G, F stop, Pulverizer E will be stopped without time Delay

LUB OIL PUMP OPERATIONSTART PERMISSIVEThe lube oil tank level is adequate.The temperature of the oil in the tank is greater than 35C MANUAL STOPThe pulverizer has been off for longer than two minutes, ORThe lube oil pump has been on for less than two minutes.AUTO SHUT-DOWNThe lube oil supply pressure is inadequate for longer than 2 seconds; 25 seconds after the pump has been started.The lube oil supply temperature > 70CThe lube oil tank temperature is inadequate < 30CThe lube oil tank level is low.

SCANNER AIR FAN CONTROLAUTO OPERATIONWhen Scanner Air to Furnace differential pressure is low,Scanner air fan A receives a start command. A two second counting period is started if scanner air fan A is not on.. scanner air fan A will receive a stop command. Scanner air fan B will receive a start command.A five second counting period is started. If the scanner duct to furnace differential pressure remains low, and the five second counting period expires and scanner air fan B receives a start command. A two second counting period is started if scanner air fan B is not on., scanner air fan B will receive a stop command and Scanner air fan A will receive a start command.A ten second counting period is started. After the scanner air fan(s) are on during the ten second counting period, the scanner duct to furnace differential pressure is increased. The ten second counting period is reset. If the ten second counting period expires, this indicates that the scanner duct to furnace differential pressure remains low, and the SCANNER DUCT TO FURNAC DELTA P LOW alarm is activated.

SCANNER AIR FAN CONTROLThe scanner air fans cannot be stopped automatically. The scanner air fan should be operated until the furnace temperature has dropped to below 140 (60C)Either scanner air fan can be placed in service manually when the Operator activates theassociated START SCANNER AIR FAN push-buttons.When both scanner air fans are on and the scanner duct to the furnace differential pressure is not low, either scanner air fan can be stopped by momentarily activating the associated STOPSCANNER AIR FAN push-button.

SEAL AIR FAN CONTROLAUTO OPERATIONWhen either Primary Air Fan is on, selected seal air fan is automatically placed in service. A two second counting period is started if selected seal air fan is not on. The two second counting period will expire if selected seal air fan remains off for more than two seconds after it was started. If this occurs, selected seal air fan will receive a stop command. Another Seal air fan will receive a start command.An alarm will be established when either Primary Air Fan is on and Seal Air Header/Cold Air Duct DP is low, both conditions present for 10 seconds. This alarm signal will automatically start the seal air fan which is stopped if the other seal air fan is started.Either seal air fan can be placed in service manually by its Start push buttons.When both seal air fans are on, Either seal air fan can be stopped by its Stop push button..The seal air fans are manually shutdown after the both primary air fans are off and no inert/transport in progress on all pulverizer elevations.

**************PULVERIZER TRIP CONDITIONS (CONTINUED)LOSS OF PA FAN TRIP CONDITIONSeven or more pulverizers are on AND Either primary air fan is not on.

The above conditions will initiate a sequence of pulverizer trips (affecting only, E,F,G,H,J and K pulverizers) until less than seven pulverizers are on. The sequence of trips is:Pulverizer K receives a trip command.

Two seconds later, pulverizer J receives a trip command.If Pulverizer K stop, Pulverizer J will be stopped without time delayFour seconds later, pulverizer H receives a trip command.If Pulverizer J stop, Pulverizer H will be stopped after Two seconds timedelayFour seconds later, pulverizer H receives a trip command.If Pulverizer J stop, Pulverizer H will be stopped after Two seconds timedelaySix seconds later, pulverizer G receives a trip command.If Pulverizer K, J, H stop, Pulverizer G will be stopped without time delayEight seconds later, pulverizer F receives a trip command.If Pulverizer K, J, H, G stop, Pulverizer F will be stopped without time delayTen seconds later, pulverizer E receives a trip command.If Pulverizer K, J, H, G, F stop, Pulverizer E will be stopped without timedelayE

*PULVERIZER TRIP CONDITIONS (CONTINUED)LOSS OF PA FAN TRIP CONDITIONSeven or more pulverizers are on AND Either primary air fan is not on.












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Mill Burner Control