BOILER OPERATION

PRE START UP INSPECTION:

PRIOR TO START UP, THE FOLLOWING PLANT SYSTEM SHOULD BE AVIALABLE.

CLEARANCE FROM MAINTENANCE GROUP. ELECTRICAL POWER, CONTROL POWER AND CONTROL SYSTEM. AIR COMPRESSOR FOR SERVICE AND INSTRUMENTATION AIR. D M PLANT, CONDENSATE WATER WITH ADEQUATE D M WATER

STORAGE. FEED WATER SYSTEM INCLUDING FEED WATER PUMPS,DEAERATOR

AND CONTROL VALVES. COOLING WATER SYSTEM COAL FEEDING, BED MATERIAL FEEDING SYSTEM. CHP UNIT AND OIL FIRING SYSTEM CHEMICAL DOSING SYSTEM BED ASH COOLERS EMISSION CONTROL SYSTEM AIR/GAS SIDE CLEARANCE. CHECK THE VALVE LIST FOR START UP POSITION CHECK OBSERVATIONS FOR EXPANSION AND DAMPER POSITION

PREPARATION:

BEFORE GOING TO BOILERSTART-UP PREPARATION OF FOLLOWING THINGS ARE TO BE CHECKED

AIR AND GAS CIRCUIT-

I D FANS-

I D FANS INLET DAMPERS(MOTORIZED)-CLOSED I D FANS OUTLET DAMPER(MOTORIZED)-OPENED I D FAN INLET CONTROL DAMPER(PNEUMATIC)-IN

MINIMUM POSITION

F D FANS-

F D FANS INLET VANES(PNEUMATIC)-IN MINIMUM POSITION

F D FANS OUTLET DAMPERS(MOTORIZED)-CLOSED AIR HEATER BYPASS DUCT ISOLATION DAMPER-

OPENED AIR HEATER INLET DUCT ISOATION DAMPER-CLOSED

ALL THE BED COMPARTMENT ISOLATION DAMPERS-CLOSED.

P A FANS-

P A FAN INLET VANES(MOTORIZED)-CLOSED P A FAN OUTLET DAMPERS(MOTORIZED)-CLOSED P A AIR TO FUEL FEED LINE DAMPERS-CLOSED P A AIR TO INDIVISUAL FUEL FEED LINE DAMPERS-

OPENEDED.

E S P-

ENSURE THAT E S P IS FREE FROM MEN AND FOREIGN MATERIAL.

ENSURE THAT E S P HOPPERS ARE FREE FROM FLY ASH ENSURE THAT THE E S P MANHOLE DOORS ARE TIGHTLY

CLOSED TO AVOID ANY AIR INGRESS INTO THE SYSTEM. FUEL HANDLING SYSTEM CHECK AND ENSURE THE AVAILABILITY OF DRY FUEL OF

RECOMMENDED SIZE IN THE BUNKER ENSURE THAT DRIVES AND CONTROL SYSTEMS ARE

READY FOR SERVICE.HORIZONTAL AND VERTICAL FUEL FEED LINES ARE CLEAR.

START UP BURNERS ENSURE THAT B M S IS READY FOR SERVICE ALL THE INTERLOCKS ARE IN SERVICE ENSURE THE AVAILABILITY OF OIL FOR

START-UP. BED ASH HANDLING SYSTEM

COOLING AIR TO BED ASH COOLER DAMPERS-CLOSED BED ASH COOLER OUTLET HOT AIR DAMPERS-CLOSED

FLY ASH HANDLING SYSTEM FLY ASH HANDLING SYSTEM FOR

HOPPER BELOW BOILER BANK SHOULD BE KEPT READY FOR OPERATION

FLY ASH HANDLING SYSTEM FOR HOPPER BELOW AIR HEATER SHOULD BE KEPT READY FOR OPERATION.

FLY ASH HANDLING SYSTEM FOR HOPPERS BELOW E S P SHOULD BE KEPT READY FOR OPERATION

D P TESTBEFORE GOING TO BED MATERIAL FILLING,WE MUST CLEANINESS OF BUBBLE CAPS,THE FLUDIZATION DEPENDS UPON THIS ASPECT.HENCE,FOR CHECKING BUBBLE CAPS CLEANINESS,WE

HAVE TO CONDUCT D P TEST THAT IS DIFFERENTIAL PRESSURE TEST ON THE BOILER.FOR CONDUCTING D P TEST THE FOLLOWING PROCEDURE HAS TO BE FOLLOWED. CLOSE ALL P A LINES BOTTOM GATES CLOSE ALL P A LINE INDIVISUAL DAMPERS AS WELL AS

COMPARTMENT MAIN P A HEADER DAMPERS. CLOSE ALL OVERFEED SECONDARY AIR DAMPERS CLOSE ALL BURNER F D AIR SUPPLY DAMPERS START I D FAN FIRST AND AND MAINTAIN BOILER FURNACE

DRAFT. THEN CHECK FOR INTERLOCK RELEASE IN F D FAN INDIVISUAL

DISPLAY ON I D FAN PATH OPEN.BEFORE STARTING F D FAN ENSURE THAT,ALL INDIVISUAL COMPARTMENT SECONDARY AIR WIND BOX DAMPERS ARE IN SHUT OR CLOSE POSITION

START F D FAN AND SLOWLY INCREASE THE AIR FLOW BY ADJUSTING INLET GUIDE VANE OPENING.WHILE DOING THIS,FURNACE DRAFT IS TO BE MAINTAINED.

BED MATERIAL FILLING AFTER COMPLETION OF D P TEST ,WITH READINGS OBTAINED,WE CAN ENSURE THE CLEANINESS OF BUBBLE CAPS.IF RESULTS ARE FOUND TO BE WITHIN LIMITS THEN WE CAN PROCEED FOR BED MATERIAL FILLING. BEFORE PUTTING BED MATERIAL INTO THE FURNACE,REMOVE PILOT FLAME GAS IGNITER AND OIL GUN FROM BURNERS,SO AS TO AVOID DUST COLLECTION OVER SPARKING AREA OF IGNITER AND CLOGGING OF ATOMIZING NOZZLE OF OIL GUN. WHILE FILLING THE BED MATERIAL INTERMITTENTLY OBSERVE THE WIND BOX PRESSURE READINGS.BY OBSERVING THE WIND BOX PRESSURE READINGS ALSO WE CAN JUDGE THE FLUIDIZATION INSIDE THE FURNACE THAT IS IF ALL THE WIND BOX PRESSURE READINGS ARE NEAR ABOUT THE SAME VALUE THEN WE CAN SAY FLUIDIZATION IS GOOD INSIDE THE FURNACE.IF THERE IS MAJOR DIFFERENCE IN BETWEEN THE READINGSOF INDIVISUAL COMPARTMENTS THEN THERE MAY BE SOME PROBLEM WITH FLUIDIZATION.IN THAT CASE WE HAVE TO STOP FILLING AND WE HAVE TO CHECK THE FLUIDIZATION PHYSICALLY INSIDE THE FURNACE. DURING THE BED MATERIAL FILLING,WE ALSO HAVE TO TAKE CARE OF THE BED MATERIAL QUALITY, THEREFORE,BED HEIGHT=(PRESENT WIND BOX PRESSURE-INITIAL WIND BOX PRESSURE) BY USING THIS FORMULA,BRING THE BED HEIGHT TO REQUIRED HEIGHT.NOW IT WILL BE BETTER TO CHECK THE FLUIDIZATION PHYSICALLY INSIDE THE FURNACE BECAUSE THERE MAY BE CHANCES OF FORMATION OF HEAPS INSIDE THE FURNACE WHILE FILLING THE BED MATERIAL.

INSPECT THE BOILER PRIOR TO STARTING AND CHECK THE FOLLOWING

STARTING EQUIPMENT INTERLOCKS ARE IN POSITION BOILER IS FED WITH D M WATER ABOVE THE LOW LEVEL

LIMIT UPTO NWL.CHECK THE FOLLOWING EQUIPMENTS FOR ADEQUATE LUBRICATION AND REDINESS FOR SERVICE

FEED PUMPS AND DRIVES FUEL FEEDER AND DRIVES MAKE SURE THAT THE TEST GAGS ARE REMOVED FROM

ALL SAFETY AND RELIEF VALVES CHECK THE INSTRUMENT AIR AND SERVICE AIR START ONE I D FAN AND OPEN THE INLET AND OUTLET

MOTORIZED DAMPERS FULLY. START ONE F D FAN AND OPEN MOTORIZED DAMPERS

FULLY PUT THE FURNACE PRESSURE CONTROL LOOP AND AIR

FLOW CONTROL LOOPIN MANUAL MODEWATER AND STEAM CIRCUIT

100% FEED LINE MOTORIZED VALVES AND BYPASS VALVES. ATTEMPERATOR LINE ISOLATION VALVES BLOWDOWN VALVES MAIN STEAM STOP VALVES. DRAIN VALUES OF WATER LEVEL GAUGES ALL DRAIN VALVES IN PANEL BOTTOM HEADERS,INBED EVAPORATORS HEADERS SAMPLING VALVES TO BE KEPT CLOSED NITROGEN FILLING LINES ON STEAM DRUM AND AND MAIN STEAM LINECHECK THE FOLLOWING VALVES FOR GOOD OPERATION AND ARE KEPT OPEN

ISOLATION VALVES AFTER FEED LINE CONTROL VAVES VALVES BEFORE AND AFTER THE FEED CONTROL

VALVES IN THE FEED LINE VALVES OF THE FEED LINE CONNECTING TO THE FEED

PUMPS IN THE OPERATION MOTORIZED ISOLATION VALVE ON FEED LINE BEFORE

ECONOMIZER BOTTOM HEADER DRUM AIR VENT PRIMARY SUPERHEATER INLET HEADER VENT AND

DRAIN SECONDARY SUPERHEATER OUTLET HEADER VENT

AND DRAIN

SECONDARY SUPER HEATER OUTLET HEADER VENT AND DRAIN

DE SUPERHEATER HEADER VENT AND DRAIN. MOTORIZED START UP VENT LINE AND VALVES VALVES OF WATER LEVEL GAUGES,PRESSURE GAUGES

AND LEVEL TRANSMITTERS ALL ISOLATION VALVES OF INSTRUMENT

START UP SEQUENCE DURING BOILER START UP EQUIPMENT SHOULD BE SEQUENTIALLY STARTED,AS PER THE REQUIREMENT.THE START UP SEQUENCE MAY BE AS FOLLOWS.IT SHOULD BE ENSURED THAT BED IS FILLED WITH BED MATERIAL

I D FAN F D FAN BURNER FEED WATER PUMP P A FAN DRAG CHAIN FEEDER DOSING PUMPS FLY ASH HANDLING SYSTEM E S P BED ASH COOLER

COLD START UP PROCEDURE START UP AFTER A LONG OUTAGE FRESH BED MATERIAL START UPAFTER SHUT DOWN LONGER THAN EIGHT HOURS,WHERE

THE BED MATERIAL IS CLOSER TO AMBIENT TEMP,BOILER IS DEPRESSURIZED

BEFORE LIGHTING UP THE BOILER,THE FOLLOWING THINGS ARE TO BE CHECKED.

CHECK FOR BURNER READINESS. CHECK FOR LPG AVIALABLE FOR LPG CYLINDER CHECK WHETHER AIR VENTSOF DRUM ,PENDENT SUPERHEATERS

ARE IN OPEN CONDITION OR NOT CHECK DRUM LEVEL.IT SHOULD BE NEAR ABOUT

ZERO,OTHERWISE MAKE IT ZERO BY OPERATING THE RESPECTIVE VALVES

CHECK WHETHER ALL THE DRUM LEVEL TRANSMITTERS ARE IN SERVICE OR NOT

AFTER CHECKING THE ABOVE POINTS,IF WE SATISFY WITH THE BOILER READINESS FOR LIGHTING-UP THE FOLLOWING PROCEDURE HAS TO BE FOLLOWED.

STARTTHE I D FAN AND OPENINLET AND OUTLET DAMPERS

MAINTAIN THE DRAFT NEARER TO -4MMWC.SINCE IF EXCESS DRAFTIS PRESENT INSIDE THE BOILER,IT WILL CARRY OVER THE FINE BEDMATERIAL PARTICLES.AND WE MAY HAVE TO ADD BED MATERIAL AGAIN FOR PROTECTING THE IN BED EVAPORATOR COIL.

SEE FOR I D PATH OPEN FEED BACK ANDFOR PROTECTION RELEASE FEEDBACK IN THE F D FAN INDIISUAL DISPLAY.

IF WE HAVE THE PERMIT TO START THE F D FAN ,THEN START THE F D FANS AND OPERATE THE OUTLET AND CONTROL DAMPERS AS PER REQUIREMENT.

AFTER THIS D C S WILL PERMIT US TO STARTTHE BURNERS. START ANY ONE OF THE L D O PUMPSAND CHECK FOR PRESSURE

BUILT-UP IN THE L D O CIRCUIT. AFTER STARTING THE L D OPUMPSWE WILL GET PERMIT TO PURGE THE

B M S PANEL. PURGE THE BOILER .IT WILL CONTINUE FOR 5MIN. AFTER CONTINUING THRE PURGINGREADY TO START THE BURNERS

INDICATION WILL APPEAR ON THE B M S PANEL. OPEN THE LPG VALVE. OPERATETHE LDO CONTROL VALVE AS PER REQUIREMEN. BEFORE GIVING THE START COMMAND CHECK THAT WHETHER

SECONDARY AIRDAMPER OF BURNERS IS INCLOSED POSITION OR NOT.IF NOT,CLOSE THE DAMPERS

STARTTHE BURNERS AND CHECK FOR FLOW METER OPERATION PROVIDED IN LDO LINE

OPERATE THE SECONDARY AIR MANUAL DAMPER AS PER REQUIREMENT.

CHECK INSIDE THE FURNACE FOR OIL SPILLAGE ANDIF ANY OIL SPILLAGE IS THERE THEN UTMOST CARE HAS TO BE TAKEN DURING LIGHT-UP.OTHERWISE THIS MIGHT CREATE LOCALIZED HEATING OF BED MATERIAL WHERE PARTICULAR SPILLAGE TAKES PLACE AND ULTIMATELY LEADS TO SOFT CLINKER FORMATION

IF ANY SPILLAGE IS THERE,THEN INTERMITTENT AIR JERKS ARETO BE GIVEN TO THE COMPARTMENT ANDIF REQUIRED TO THE SECOND COMPARTMENT ALSO FOR PREVENTING THE CLINKER FORMATION.

AFTER ADJUSTINGTHE FLAME ANGLE INSIDE THE FURNACE,OBSERVE THE FURNACE TEMP,AND PENDANT SUPERHEATER TEMP.

WHEN FURNACE TEMP RAISES TO ABOUT TO 100 DEGREE CENTIGRATE,THEN PROCEED TO CLEAR THE P A LINES OF FIRST COMPARTMENT.

AFTER CLEARING THE FIRST COMPARTMENT P A LINES CHECK INSIDE THE FURNACE FOR BED MATERIAL FLUIDIZATION AT THE PORTION OF COAL NOZZLES.IF FLUIDIZATION IS OBSERVED THEN IT IS OK,OTHERWISE GO FOR CHECKING OF P A LINES BY CHECKING THE SUCTION AFTER REMOVAL OF PLUG PROVIDED AT MIXING NOOZZLE THROATPORTION

IF ALL TEMP ARE INCREASING STEADILY,IT INDICATES THAT FLUIDIZATION IS GOODIN THE ENTIRE COMPARTMENT AREA AND FURNACE IS IN HEALTHY CONDITION.

IF SOME OF THE TEMP ARE IN RAISING TRENDAND SOME ARE STABLE,CHECKTHE FURNACE IN THE FIELD FOR FLUIDIZATION.

IF EVERYTHING IS GOING RIGHT WAY THEN OBSERVE FURNACE TEMP,PENDENT SUPERHEATER TEMP AND BED TEMP CONSTANTLY.

WHEN THE MAIN STEAM HEADER PRESSURE IS ABOUT2-3KG/CMSQUARE,CLOSE THE PRIMARY SUPERHEATER AIR VENTS FIRST AND THEN DRUM AIR VENT.OPERATE START-UP VALVE ACCORDING TO NECESSITY BY OBSERVING THE PRIMARY SUPER HEATER TEMP,MAIN STEAM HEADER PRESSURE AND MAIN STEAM TEMP

OBSERVE THE DRUM LEVEL AND IF REQUIRED OPERATE RESPECTIVE VALVES.

WHEN THE BED TEMP ARE IN RANGE OF400-450 DEGREE CENTIGRATE START THE COAL FEEDER AND START MINIMUM COAL FEEDING INTERMITENTLY IN THE EARLIER STAGE AND LATER ON CONTINOUSLY AND EVERY TIME OBSERVE THE OXYGEN % IN FLUE GASES.

AFTER CONFIRMING THAT THE COAL IS IGNITED,CONSTANTLY OBSERVE THE BED TEMP.

WHEN TEMP IS I THE RANGE 700-800 DEGREE CENTIGRATE THEN CUT OFF ONE OF THE BURNERS AND OBSERVE THE BED TMP OF THE FIRST COMPARTMENT.

AFTER ATTAINING TEMP OF 800-850 DEGREE CENTIGRATE CUT OFF EVEN THE SECOND BURNER AND OBSERVE THE BED TEMP.

CLEAR SECOND COMPARTMENT P A LINESAND OBSERVE FOR FLUIDIZATION IN THE SECOND COMPARTMENT IN THE FURNACE ZONE.BEFORE CLEARING P A LINES CONFIRM THAT WIND BOX DAMPER IS IN CLOSED POSITION.

AFTER ATTAINING A TEMP IN THE RANGE OF800-850 DEGREE CENTIGRATE IN IN THE FIRST COMPARTMENT,GIVE A SMALL JERK TO THE SECOND COMPARTMENT FOR TRANSFFERING THE HEAT FROM FIRST COMP TO SECOND COMP.BEFORE GIVING THE JERK TO THE SECOND COMPCHECK THAT WHETHER AIR FLOW QUANTITY IS SUFFICIENT FOR FLUIDIZING BOTH COMP ARE NOT AND ALSO FOR COMPLETE BURNING OF COALIN THE FIRST COMPARTMENT.

AFTER GIVING JERK ,OBSERVE THE FIRST AND SECOND COMPARTMENT TEMP.FIRST COMP TEMP WILL COME DOWN SLIGHTLY AND SECOND COMP TEMP WILL RISE SLIGHTLY.

AFTER SOMETIME,FIRST COMP TEMP WILL RISE.THEN AGAIN GIVE SMALL JERK TO SECOND COMP.,BY OPERATING THE WIND BOX DAMPER OF SECOND COMP.EVERY TIME CHECKTHAT WHETHER AIR FLOW IS SUFFICIENT OR NOT.

AFTER ATTAINING THE TEMP IN THE RANGE OF 400-450 DEGREE CENTIGRATE IN THE SECOND COMPSTART THE COAL FEEDER OF SECOND COMP AND START MINIMUM COAL FEEDING.

INTERMITTENTLY CHECK THE FURNACE FOR FLUIDIZATION AND FOR COLOUR.

CLEAR P A LINE OF THIRD COMP ALSO. APPLY THE SAME PROCEDURE FOR TAKING OTHER COMP IN SERVICE OPEN THE MAIN STEAM BYPASS VALVE FOR HEATING THE STEAM LINE

FOR CONNECTING THE BOILER TO MAIN STEAM LINE HEADER.WHEN THE MAIN STEAM OUTLET TEMP OF THE BOILER IS NEARE TO RATED VALUE.OPERATE THE DESUPERHEATER ISOLATION VALVE AND PUT THE DE SUPERHEATER CONTROL VALVE INTO OPERATION

WHEN THE RATED PRESSURE AND TEMP ARE ATTAINED AT THE OUTLET OF BOILER,WE CAN PROCEED TO CONNECT THE BOILER TO MAIN STEAM HEADER.

AFTER CONNECTING THE BOILER TOMAIN STEAM LINE HEADER,CLOSE ALL THE BOILER HEADER DRAINS.

ISOLATE THEBURNER CONTROL PANEL AND STOP LDO PUMPS,ALSO ISOLATE THE LPG SYSTEM

CHECK ALL THE FANS FOR OPERATION.IF ANY ONE OF THEM ARE RUNNING REDUNTANTLY,STOP THEM THROUGH CONFIRMATION OF THEIR REQUIREMENT.

HOT START –UPCASE-1

THE UNIT HAS BEEN OFF LNE FOR ONE HOUR.THE MATERIAL IN START UP COMP IS ABOVE 600DEGREE CENTIGRATE.THE FOLLOWING SEQUENCE MAY BE FOLLOWED TO BRINGTHE BOILER BACK INTO SERVICE.THE BED THERMOCOUPLES SHALL BE PROTECTED ONCETHE BED IS FLUIDIZED.

OPEN THE START UP VENT VALVE SLIGHTLY. CLOSE ALL THE COMP DAMPERS START THE I D FAN F D FAN AND P A FAN AS PER THE FAN START

UP PROCEDURE. OPEN SLIGHTLY THE WIND BOX DAMPER IN BED NO.1 SO THAT

BED NO.1 FLUIDIZE WITH MINIMUM AIR,ENSURE THAT FLUIDISATION IS UNIFORM AND SATISFACTORY.

ADJUST THE I D FAN INLET DAMPER TO MAINTAIN THE FURNACE PRESSURE

ADJUST THE F D FAN AND P A FAN CONTROL DAMPERS TO GET THE REQUIRED FAN PRESSURE

CLEAR THE VERTICAL LINES OF COAL FEED LINES TO BED NO.1 START COAL FEEDING WITHOUT DELAY OTHERWISE BED MAY

COOL DOWN RAPIDLY.IF THE TEMP IS LOST,BURNERS SHALL BE THE BACK UP.

GRADUALLY INCREASE THE COAL FEEDING OBSERVING THE RISE IN BED TEMP

ADJUST THE AIR FLOW AND COAL FLOW TO STABILIZE THE BED TEMP

TAKE BED NO.2 AND OTHER BED ON LINE AND CONNECT THE BOILER FOR PROCESS AS PER THE COLD START UP PROCEDURE

TAKE FEED WATER CONTROL AND FURNACE DRAFT ON AUTO MODE

CHARGE THE E S P IF THE FLUE GAS TEMP IS OK. PUT THE BOILER ON AUTO MODE.

CASE-2 AFTER THE BOILERTRIP,IF THE BED TEMP IS LESS THAN 600 DEGREE CENTIGRATE THE FOLLOWING SEQUENCE HAS TO BE FOLLOWED TO BRING THE BOILER BACK INTO SERVICE

START I D FAN,F D FAN AND P A FAN AS PER THE FAN START UP PROCEDURE

IF THE BED LEVELIS TOO HIGH DRAIN THE BED MATERIAL AND BRING DOWN BED HEIGHT TO THE REQUIRED LEVELBY FLUIDIZING THE BED NO.1.START THE OVERBED BURNERS.

REPEAT THE COLD START UP PROCEDURE AND STABILIZETHE BOILER TO REQUIRED LEVEL.

FULL LOAD OPERATIONTHE BOILER CAN BE OPERATED AT FULL LOAD BY MAINTAINING THE FOLLOWING CONDITION

BY KEEPING ALL THE BEDS UNDER ACTIVE CONDITION. WITH ADEQUATE BED LEVEL. WITH ADEQUATE BED TEMP FUEL SEIVE ANALYSIS AS PER THE DESIGNED CONDITIONS.FULL

LOAD OPERATING CONDITION NEED TO BE MAINTED.

BED LEVEL CONTROL OR ASH DRAININGDURING BOILER OPERATION,BED ASH ACCUMULATES INSIDE THE BED AND SHOULD BE DRAINEDAT REGULAR INTERVALS TO MAINTAIN ADEQUATE BED LEVELS FOR EFFECTIVE FLUIDISATION FOR GOOD COMBUTIN AND MEET THE REQUIREDSTEAM DEMAND. FREE SILICON OXIDE ALUMINIUM OXIDE AND IRON OXIDEARE HARD AND STRONG.ALL THIS COMPONENTS ARE PRESENT INBED MATERIAL.THE GREATER % OFTHEIR COMPONENTS,GENERALLY MORE IS THE EROSION RATES.EROSION RATE IS MAINLYDEPENDENT ON SILICON OXIDE TO ALIMINIUM OXIDE RATIO. IF THE RATIO IS 1.5,THE MATERIAL IS VERY SOFT.WHEN THE RATIO IS BEYOND 1.5,EROSION RATE INCREASES.WHEN THE RATIO IS IN THE RANGE 1.5-3.0 THE EROSION IS MODERATE.IF THE RATIO IS BEYOND 3.0,EROSION RATE WILL BE VERY HIGH.

SOIN ORDER TO REDUCE THE EROSION RATE IT IS VERY ESSENTIAL TO MANAGE THE BED CHEMISTRY WITHIN THE LIMITS.FOR THIS REASON THE FREQUENT BED ASH DRAINING AND ADDITION OF FRESH MATERIAL SHOULD BE FOLLOWED RELIGIOUSLY OPERATING THE BOILER AT OPTIMUM BED HEIGHT ALSO REDUCES THE EROSION RATE. PRESSURE DROP ACROSS THE BED WILL INCREASE WITH THE ACCUMULATION OF BED ASH.THIS WILL REFLECT ON INCREASE ON WIND BOX PRESSUREGRADUAL INCREASE IN WIND BOX PRESSURE INDICATES THE ACCUMULATION OF BED ASH.CONSEQUENTLY QUALITY OF AIR FLOW THROUGH BED,WIND BOX PRESSURE MAY HAVE TO BE MAINTED AT HIGHER LEVEL AT THE EXPENCE OF HIGH PRESSURE DROP.THIS IN TURN WILL INCREASE THE POWER CONSUMPTION OF F D FAN. APART FROM WIND BOX PRESSURE INDICATORS,BED LEVEL INDICATORS ARE ALSO PROVIDED FOR BED COMP.THISGIVES THE BED HEIGHT IN FLUIDIZED CONDITION. IF THE BED HEIGHT LEVEL IS TOO LOW BOILERLOAD CANNOT BE INCREASED TO RATED CAPACITY.AT THIS CONDITION,SIEVED SAND AS PER THE SIZE SPECIFIED OR SIEVED BED ASH OR CRUSHED REFACTORY OR LIME STONE MAY BE USED AS A BED MAKE UP MATERIAL TO MAINTAIN THE BED LEVEL TO THE REQUIREMENT RATE OF ACCUMULATION OF BED ASH DEPENDS ON COAL SIZE DITRIBUTION.WITH HIGHER % OF FINE IN THE COAL,ASH ACCUMULATION IN THE BED WILL BE LESS.COAL WITH VERY LESS % OF FINES CONTRIBUTES FOR HIGH BED ACCUMULATIONAPART FROM SIZING,ASH CONTENT IN THE COAL ALSO DECIDE THE ASH ACCUMULATION LEVELS IN THE BED. ALONG WITH COAL,STONES OR SHELL ALSO ENTERS THE FURACE AND ACCUMULATES IN THE FURNACE BOTTOM WHICH ALSO INCREASES THE WIND BOX PRESSUREBED DRAINING TO BE DONE FREQUENTLY TO REMOVE THE ACCUMULATED STONE OR SHELL TO KEEP THE BED HEALTHIER AND TO AVOID CLINKER FORMATION AND FOR TROUBLE FREE OPERATION. IF DRAINED BED ASH HIGHER SIZED PARTICLES IT IS NECESSARY TO DRAIN FREQUENTLY.ALL THIS HIGHER SIZED PARTICLES SETTLE AT THE BOTTOM AND WILL NOT FLUIDISE PROPERLY AND MAY END UP IN CLINKER FORMATION. SO CONSIDERING THE ACTUAL BED,FUEL CONDITION AND FOREIGN MATTER,OPERATOR SHOULD ACT ACCORDINGLY TO MAINTAIN THE REQUIRED BED LEVEL FOR TROUBLE FREE OPERATION.IF REQUIRED BED MATERIAL TO BE ADDED FOR HEALTHIER CONDITION.

BED TEMP CONTROL

BED TEMP IS MEASURED BY BED THERMOCOUPLES AND ARE INSERTED THROUGH THE BOTTOM OF FURNACE TO AVOID EROSION.PROTECTIO IS PROVIDED BY USING SS310 BAR STOCK AS THE THERMO WELL MATERIAL AND THE OUTER PROTECTION TUBE FOR THE PORTION PROJECTING INSIDE THE BED. DEPENDING UPONTHE BED LEVEL OR THE BOILER LOAD THE BED TEMP VARIES.BED TEMP CAN EBE CONROLLED BY ADJUSTING THE AIR FLOW TO THE COMP.MORE AIR FLOW CAN LEAD FOR LOW BED TEMP FOR A CONSTANT FUEL FEED. WHILE INCREASING THE AIR FLOW.THE AIR FLOW WILL INCREASEMOMENTARILY AND WILL DROP DOWNSO THE OPERATOR SHOULD BE CAREFUL WHLE ADJUSTING THE AIR FLOW TO AVOID CLINKER FORMATION.FUEL AND AIR SHOULD BE ADJUSTED TO GET THE REQUIRED BED TEMP DEPENDING UPON THE LOAD.

CHECK IST DURING OPERATION CHECK FOR UNUSSUAL NOISES FROM STEAM OR WATER

LEKAGES CHECK FOR UNUSUAL TRACES FOR WATER ON FLOOR CHECK FOR OIL SPILL AROUND THE BURNER LOOK FOR GLAND AND VALVE LEKAGES DISCOLOURATION,HOTSPOTS AND BULGING ON CASING ,DUCTS

AND HOPPERS CHECK FOR STEAM AND WATER LEAKS FROM CONNECTION AND

FITTING TO THE DRUM. WATCH THE FURNACE FOR ANY CLINKER FOR BAGASSE PILE

UP,IF POSSIBLE INSPECT THE SLAGGING CONDITION OF FURNACE WALLS AND SUPERHEATER COILS THROUGH THE OBSERVATION PORTS.

WALK AROUND THE FURNACE EXTERIOR AND OBSERVE FOR ANY HOT SPOTS OR GAS LEKAGES

LISTEN FOR ANY UNUSUAL NOISE AROUN ECONOMISER WHICH MAY INDICTE ECONOMISER LEAK OR HISSING NOISE

INSPECT PENT HOUSE FOR GAS LEKAGES.INSPECT WIND BOX FOR ANY AIR LEKAGE,SIGNS OF OVERHEATING THAT MAY INDICATE WIND BOX FIRES OR HOT AS RECIRCULATION WITHIN THE WIND BOX.

INSPECT ALL ASH HOPPERS TO MAKE SURE THAT THEY ARE BEING EMPTIED PROPERLY.

CHECK AROUND ALL AIR AND FLUE DUCT FOR LEKAGES. CHECK POSITION OF FANS AND FIELD DAMPERS. CHECK FOR ANY GAS LEKAGE FROM REFACTORY SEALING CHECK FOR LEKAGE FROM SAFETY VALVES AT NORMAL

OPERATING PRESSURE.ALSO NOTE THE SAFETY VALVE BLOW OFF AND SHUT OFF PRESSURE.CHECK THAT THE DRAIN LINES ANDAND DRIP PANS ARE NOT PLUGGED.

MAKE NOE OF ANY LEAKY VALVE AND PREPARE MAINTENANCE SHEDULE TO REPAIR IT

CHECK TO SEE THAT PROPER WATER LEVEL IS BEING SHOWN BY DIRECT WATER LEVEL GAUGE.CHECK FOR WATER OR STEAM LEAKS FROM PORTS OR DRAIN CONNECTION WHICH WILL CAUSE A FALSE WATER LEVEL IN GAUGE GLASS.INSPECT THE GLASS FOR DISCOLOURATIO OR FOULING.

WHILE DOING ROUTINE OPERATION OF SOOT BLOWING INSPECT FOR CONDENSATE,STEAM AND LEAKS FROM SOOT BLOWER.

FANS INSPECT BEARING LUBRICATION AND CHECK FOR PROPER OIL

OR GREASELEVEL IF RING OILED,CHECK FOR FREE ROTATION AND

ADEQUQTELY DISTRIBUTED OIL CHECK BEARING TEMP,IF HOT,DETERMINE CAUSE AND

RECTIFY IT. ENSURE CONTINUOUS WATER FLOW TO WATER COOLED

BEARINGS IF PROVIDED. LISTEN FOR ANY UNUSUAL NOISES IN THE FAN. FEEL AND INSPECT FOR ANY VIBRATION INSPECT BEARING SEALS. CHECK FOR ANY ABNORMALITIES IN COUPLING.

MOTORS CHECK FOR UNUSUAL NOISES AND INSPECT FOR

VIBRATION. CHECK FOR WINDING TEMP,BEARING TEMP. CHECK CURRENT AND VOLTAGE.

COMPRESSOR CHECK OIL LEVEL. CHECK COOLING WATER FLOW TO AIR COOLER. ENSURE THAT COMPRESSOR DISCHARGE VALVE IS IN OPEN

CONDITION.

FEED WATER PUMPS ENSURE PROPER WATER LEVEL IN DEAERATOR TANK. OPEN SUCTION VALVE FULLY OPEN RECIRCULATING VALVE FULLY. OPEN BALANCING LINE VALVE FULLY CLOSE DISCHARGE VALVE FULLY. ENSURE COOLING WATER FLOW TO STUFFING. CHECK LUBRICATING OIL LEVEL

I D FAN

CLOSE SUCTION DAMPER FULLY. OPEN OUTLET DAMPER FULLY. CHECK LUBRICATION.

F D FAN I D FAN IN RUNNING CONDITION CLOSE SUCTION DAMPER. CHECK LUBRICATION.

P A FAN I D AND F D ARE IN RUNNING CONDITION. CLOSE SUCTION DAMPER. CHECK LUBRICATION.

ROTATING AIR LOCK VALVE CHECK THE AIR LEVEL IN THE GEAR BOX. ENSURE CHAIN TIGHTNESS.

EMERGENCY PROCEDURES AT ANY EMERGENCY CONDITION,IT IS ADVISABLE TO INITIATE THE FOLLOWING ACTIONS TO SAFE GUARD MEN AND EQUIPMENT.

UNABLE TO MAINTAIN DRUM LEVEL ACTION

TAKE THE DRUM LEVEL LOOP IN MANUAL MODE. REDUCE THE DRUM LEVEL IMMEDIATELY BY OPERATING THE

INTERMITTENT BLOW DOWN TO MAINTAIN THE DRUM LEVEL IF IT IS HIGH.

REDUCE THE STEAM DISCHARGE RATE,IF NECESSARY. START THE STANDBY COMPRESSOR IF REQUIRED. ANALYSE THE WATER QUALITY(ALKALINITY AND SOLIDS).

FURNACE PUFFING AND BACK FIRINGCAUSES

UNCONTROLLED FEEDING OF FUEL INTO THE COMBUSTOR. UNCONTROLLED AUXILIARY FUEL FEEDING. MALFUNCTIONING OF FURNACE DRAFT CONTROL SYSTEM. SUDDEN INCREASE IN F D FAN AIR. TUBE RUTURE.

ACTION TAKE THE FURNACE DRAFT AND AIR FLOW CONTROL SYSTEM INTO

MANUAL MODEAND MAINTAIN THE FURNACE PRESSURE.

NEVER INCREASE FUEL OR AUXILIARY FUEL OR AIR FLOW SUDDENLY. IN CASE OF TUBE FAILURE TAKE THE BOILER OUT OF SERVICE

IMMEDIATELY.

BOILER EXPLOSIONCAUSES

ACCUMULATION OF FUEL IN THE FURNACE DUE TO INCOMPLETE COMBUTION DUE TO LOSS OF IGNITION DUE TO FUEL VALVE LEKAGE DUE TO FREQUENT STAR-UPS

WITH THE MIXTURE OF UNBURNT FUEL WITH AIR IN EXPLOSIVE PROPORTIONS AND THE APPLICATION OF HEAT SUFFICIENT ENOUGH TO RAISE THE TEMP OF THE MIXTURE TO IGNITION POINT.

ACTION TRIP THE FIRING SYSTEM IMMEDIATELY. EVACUATE THE FURNACE TO THE POSSIBLE EXTENT. ANALYSE THE REASONS FOR EXPLOSION AND RECTIFY THE SYSTEM.

BOILER IMPLOSIONCAUSES

SUDDEN TRIPPING OF FUEL TO FURNACE. TOO NEGATIVE FURNACE DRAFT DUE TO FAILURE OF FURNACE

PRESSURE CONTROL SYSTEM.

ACTION IN CASE OF SUDDEN FUEL TRIP TAKE THE DRAFT CONTROL SYSTEM

INTO MANUAL MODE AND MAINTAIN THE FURNACE PRESSURE. RESTART THE FUEL FEEDING SYSTEM ,IF POSSIBLE.

EMISSION CONTROLSULPHUR DIOXIDESULPHUR IN COAL REACTS WITH OXYGEN AND FORMS ULPHUR DIOXIDE. SULPHUR DIOXIDE CONTROL IS REQUIRED.WHEN GASEOUS SULPHUR DIOXIDE COMBINE WITH WATER IT FORMS DILUTE SOLUTIONS OF SULPHUROUS ACID.SULPHUROUS ACID CAN EASILY OXIDISE IN THE ATMOSPHERE TO FORM SULPHURIC ACID.DILUTE SULPHURIC ACID IS A MAJOR CONSTITUENT OF ACID RAIN. SO THE SULPHER DIOXIDE IS NEEDED TO BE CONTROLLED IN THE COMBUSTER.A VARIETY OF SULPHUR DIOXIDE CONTROL PROCESSES AND TECHNOLOGIES ARE IN USE.IN FBC BOILER FURNACES,DUE TO OPERATING TEMP IT IS POSSIBLE TO USE AN INEXPENSIVE MATERIAL LIKE LIMESTONE OR DOLOMITE AS A SORBENT TO SULPHUR DIOXIDE FROM FLUE GAS.WHEN

LIMESTONE OR DOLAMITE IS ADDED TO THE BED,A REACTION OCCURS IN THE FURNACE. CALCINATION IS AN ENDOTHERMIC REACTION CaCO3+766btu/lb CaO + CO2

THE RESULTANT CaO REACTS WITH GASEOUS SO2 AND OXYGEN EXOTHERMICALLY TO FORM CaSO4

CaO +SO2 +1/2 O2 Ca SO4 +6733 btu/lb

CaSO4 IS A CHEMICALLY STABLE AT FLUIDIZED BED OPERATING TEMP AND IS REMOVED FROM THE SYSTEMAS A SOLID ALONG WITH ASH FOR DISPOSALTHIS WILL ELIMINATE THE USE OF SCRUBBERS. DOLAMITE WHEN INTRODUCED INTO THE BED ,CALCINES TO FORM A SOLID MIXTURE OF CaO AND MgO .CALCIUM OXIDE FORMS CALCIUM SULPHATE BUT MAGNISIUM OXIDE IS UNREACTIVE.

DOLAMITE LIMESTONE CaCO3+MgCO3 CaO.MgO + 2CO2

CaO.MgO + SO2 + 1/2 O2 CaSO4.MgO HYDRATED LIME(CALCIUM HYDROXIDE)

Ca(OH)2 Mg(OH)2 CaO.MgO + 2H2O

CaO.MgO + SO2 +1/2 O2 CaSO4.MgO

CONTROL OF CARBONMONOXIDE EMISSION THE BUBBLING OF BED BOILER IS DESIGNED TO MAXIMISE THE BURN OUT OF CARBONMONOXIDE TO CARBONDIOXIDE IN THE FURNACE IS ACHIEVED BY PROVIDING DEQUATE MIXINGAND TURBULENCE FOR THE GAS.THE DESIGN OF THE COMBUTION AIR SYSTEM ALLOWS CONSIDERABLE CONTROL AND VARIATION IN THE PATTERN OF AIR DISTRIBUTION OF THE FURNACE. THE LEVEL OF SECONDARY AIR NOZZLE ARE LOCATED IN GAS RICH ZONE TO PROMOTE GOOD AIR PENETRATION.

NORMAL SHUT DOWN PROCEDURE REDUCE LOAD AT THE RATE ESTABLISHED BY THE TURBINE OR AS PER

PROCESS REQUIREMENTS UNTIL THE MINIMUM LOAD POINT STEAM FLOW IS DECREASED BY REDUCING FUEL FEED RATE AND

COMBUTION AIR FLOW. IN EITHER MANUAL OR AUTOMATIC OPERATION,THE AIR FLOW

FOLLOWS THE FEL FLOW ON DECREASING LOAD OPEN THE STEAM VENTS DOWN STREAM OF THE SECONDARY

SUPERHEATER TO MAINTAIN AT AT LEAST 10% MCR COOLING

STEAM FLOW TO PROTECT THE SUPER HEATER FROM AIR HEATING.

STOP THE BOILER BY STOPPING THE FUEL FEED SYSTEM AS FOLLOWS. CLOSE THE GATE BELOW COAL BUNKERS AND SAND SILO. EMPTY OUT THE FUEL FEEDERS AND STOP THE SAME. EMPTY OUT THE SAND IN THE CHUTE. START THE ABOVE BED BURNERS TO ASSIST WITH THE BURN UP

OF THE PRIMARY ZONE AND UNBURNT CARBON PARTICLES IF ANY.

DURING THE PERIOD OF LOAD REDUCTION,THE OPERATOR SHOULD,THE OPERATOR SHOULD MAINTAIN STEAM FLOW THROUGH SUPERHEATORS.THE OPERATOR SHOULD MAINTAIN THE STEAM FLOW THROUGH THE SUPERHEATERS .THE OPEATOR SHOULD ADJUST THE FIRING RATE SO AS TO BRING THE BOILER DOWN AND STILL PROVIDE AT LEAST 10% STEAM FLOW FOR THE SUPERHEATER COILS UNTIL THE FLUE GAS TEMP IS BELOW 500 DEGREE CENTIGRATE.

IF THE UNIT IS SHUT DOWN FOR A SHORTER PERIOD OF TIME NO PERSONNEL WILL BE ALLOWED TO ENTER THE BOILER.IF OPERATING PERSONNEL NEED TO ENTER THE UNIT,THE UNIT,THE AIR HEATER HOPPERS AND THE ESP HOPPERS MUST BE EMPTIED COMPLETELY OF ANY SOLIDS ,ASH AND THE ENCLOSED TEMP COOLED BELOW 50 DEGREE CENTIGRATE FOR MAINTAINACE AND INSPECTION.

SHUT DOWN PROCEDURE PURGE THE BOILER FOR FIVE MINUTES AS PER PURGE

REQUIREMENT. INCREASE THE AIR FLOW TO THE MCR THROUGH THE PRIMARY AND

SECONDARY AIR PORTS,TO COOL THE STORED BED MATERIAL.CONTINUE THE AIR FLOW AND BED MEDIA CIRCULATION UNTIL BED OR HOPPER TEMP REACH AROUND 260 DEGREE CENTIGRATE.

WHETHER THE FURNACE GAS TEMP HAS COOLED BELOW 500 DEGREE CENTIGRATE,STEM FLOW IS NO LONGER REQUIRED TO COOL THE SUPER HEATERS.

UNLESS BED DRAINING IS REQUIRED,SHUT DOWN THE F D ,P A AND I D FANS.OPEN THE FAN INLET VANES AND DAMPERS TO ALLOW FOR NATURAL DRAFT.

DRAIN THE SOLID ACCUMULATED IN THE HOPPERS TO ASH DISPOSAL.

IF PERSONNEL ARE TO ENTER THE WHILE THE UNIT IS DOWN THEN THE BED MATERIAL IN THE FURNACE BED,STORAGE HOPPERS AND THROUGH AIR HEATER HOPPERSMUST BE REMOVED COMPLETELY FOR PERSONNEL PROTECTION

USE PRIMARY AIR FLOW TO FLUIDIZE THE BED START THE BED DRAINING SYSTEM.

AFTER THE BED MATERIAL FLOW FROM THE BED DRAIN HAS STOPPED,A LAYER OF DEAD BED WILL REMAIN IN THE

BED.THIS LAYER MUST BE VACUMED OUT BEFORE ANY ADMISSION TO THE BOILER.THE BED MEDIA TEMP MUST BE 50 DEGREE CENTIGRATE OR LESS BEFORE ANY ATTEMPT TO GET INTO THE BED FOR VACCUME APPLICATION.AFTER THE UNIT HAS COOLED TO SAFE TEMP BELOW 50 DEGREE CETIGRATE,SHUT DOWN THE I D F D AND P A FANS THEN VACCUME THE REMAINING BED MATERIAL FROM THE FURNACE. SHUT DOWN ALL THE AUXILLARY EQUIPMENT AT THIS TIME.THIS WILL INCLUDE THE FEED WATER SYSTEM,MAKE UP SYSTEM,BED DRAIN ASH REMOVAL SYSTEM.IT IS RECOMMENDED THAT A POSITIVE PRESSURE OF NITROGEN IS MAINTAINED IN THE DRAINABLE CMPONENTS ANYTIME THE UNIT IS OUT OF SERVICE,WHETHER STANDING WITH OR WITHOUT WATER,FOR LONGER THAN TWO WEEKS.A NITROGEN BLANKER SHOULD BE MAINTENED THROUGH A ‘T’ FITTING ON THE DRUM VENT,CROSS OVER PIPING VENT BETWEEN PRIMARY AND SECONDARY SUPERHEATER AND THE OUTLET DRAIN CONNECTION.

TROUBLE SHOOTING CHART

INDICATION PROBABLE CAUSE SOLUTIONCLINKER FORMATION MORE FUEL IN THE COMBUSTER

LESS AIR FLOW TO THE COMBUSTERLOW ASH FUSION TEMPSODIUM POTASSIUM SALTS IN BED MATERIAL OR FUEL

CONTROL FUEL OR AIR FLOW TO THE COMBUSTERBED TEMP SHOULD NOT BE ABOVE ASH FUSION TEMPGOOD START UP AVOIDS CLINKER FORMATIONANALYSE FUEL OR SAND FOR Na OR K

HIGH BED TEMP LESS FINES IN THE FUEL.LOW AIR TO THE COMBUSTER.BIGGER FUEL SIZE.EXCESSIVE FUEL IN COMBUSTER.LOW BED HEIGHT IN THE COMBUSTER.

CORRECT THE FUEL SIZE AND ADJUST THE AIR FLOW.CUT THE FUEL FEED.INCREASE THE BED HEIGHT BY FEEDING SAND.

LOW BED TEMP EXCESS AIR TO THE COMBUSTORBED PACKING DUE TO STONES AND SHELLS.CLINKER IN THE REGION.

CORRECT THE FUEL SIZE AND ADJUST THE AIR FLOW.DRAIN THE BED AND CUT HEAVY MATERIALS FROM THE BED.

BED TEMP VARIATION UNEVEN COAL CONCENTRATION IN THE BED.

ADJUST THE FUEL FEEDING SETTING.

UNABLE TO MAINTAIN DRUM LEVEL.

SLIGHT LEKAGE FROM THE TUBE.LEKAGE FROM THE TUBE SHEET.

REMOVE THE BOILER FROM SERVICE AND ARREST TUBE LEAK.

EXCESSIVE WATER LEVEL FLUCTUATION.

EXTREME LOAD SWINGS.FLUCTUATING WATER SUPPLY.CONTROL SYSTEM MALFUNCTIONING

CONTROL LOAD FLUCTUATIONS.SET RIGHT FEED WARTER SUPPLY

SOUND OR STEAM HEAVY LEKAGE FROM TUBE. REMOVE THE BOILER FROM

BLOWING IN FURNACE OR STEAM VISIBLE FROM STACK.

TUBE SHEET LEKAGE. SERVICE AND ATTEND REPAIRS.

STEAM EXPLOSION IN FURNACE

SUDDEN TUBE RUPTURE REMOVE THE BOILER FROM SERVICE.REPLACE THE TUBE.INSERT SPOOL PIECE.CHECK THE POSSIBILITY OF SPOOL BLOKAGE.

HIGH CONDUCTIVITY IN STEAM

SOLID CARRY OVERHIGH BOILER WATER CONCENTRATIONEXCESSIVE WATER LEVEL.LOAD FLUCTUATIONS.

CHECK WATER CONTAMINATION.CHECK FOR BAFFLE LEKAGE.MAINTAIN NORMAL DRUM LEVEL.

HIGH BACK END TEMP LOW HEAT TRANSFER SURFACE.HEAVY COMBUSTION IN UPPER FURNACE.ASH DEPOSIT ON HEATING SURFACE.TOO MUCH FINES IN THE FUEL.HIGH EXCESS AIR.

CLEAN THE HEAT TRANSFER AREA.REDUCE FINES IN THE FUEL.ADJUST THE AIR SLIGHTLY.

HIGH SUPERHEATER TEMP.

HIGH FLUE GAS TEMP.NO CIRCULATION OF STEAMCOMBUTION OF FINES IN THE UPPER FURNACE.

ACHIEVE STEAM CIRCULATION BY OPENING THE START UP VENT.REDUCE FINES IN THE FUEL.REDUCE AIR FLOW SLOWLY.

LOW SUPERHEAER TEMP.

LOW FLUE GAS TEMPWATER CARY OVER IN STEAM.HIGH WATER LEVEL IN STEAM DRUM.

CONTROL THE DRUM LEVEL.INCREASE AIR SUPPLY.DRAIN THE BED AND ALLOW THE EXCESS FUEL IN THE BED TO ESCAPE.

CARRYOVER OF WATER

DRUM LEVELIS VERY HIGH.START UP VENT OPENING % MAY BE VERY HIGHHEAVY LOAD FLUCTUATIONS.DRUM INTERNAL LOOSENESS.

CONTROL DRUM LEVEL,OPEN THE CBD VALVE.IF START –UP VENT % OPENING IS HIGH,CONTROL IT.

NON UNIFORM DISTRIBUTION OF FUEL.

BED TEMP VARIATIONS.CHOCKING OF SOME COAL FEED LINES.FUEL BRIDGING IN THE HOPPER ABOVE FEEDERMORE FUEL PASSING THROUGH SOME FUEL FEED LINES DUE TO WHICH LOCAL CONCENTRATION OF FUEL INCREASES IN BED.

CHECK THE DP ACROSS MIXING NOZZLE.IF LESS CLEAR CHOCKING IN THE FUEL FEEDLINES.THE FUEL FEEDER DISCHARGE MAY NEED MODIFICATION.

CARRY OVER OF ASH HIGH NEGATIVE PRESSURE OF THE FURNACE.EXTERNAL METAL LOSS OR HIGHLY POLISHED SURFACE OF THE FURNACE TUBES.

MAINTAIN FURNACE PRESSURE.AVOID STONES IN THE FUEL.AVOID USING HIGH ASH COAL.

UNABLE TO MAINTAIN BOILER WATER CONCENTRATION.

TUBE LEKAGE DUE TO PITTING OR CRACKING.TUBE SEAT LEAK.

REMOVE BOILER FROM SERVICE.HYDRAULIC TEST TO LOCATE LEAK.REPAIR BY WELDING.DETERMINE THE CAUSE OF FAILURE AND

CORRECT IT.OPERATIONS AT NORMAL LOADSSHOULD CHEMICAL BACK IN SOLUTION.

HIGH GAS TEMP GAS BAFFLE LEAK OR DIRTY HEATING ELEMENTS.

INCREASE THE FREQUENCY OF SOOT BLOWING PRESSURE.INSPECT THE UNIT FOR HOLES IN GAS BAFFLE.

BOWED WATER WALL GENERATING TUBES

INTERNAL DEPOSITS OR LOW DRUM LEVEL.USUALLY INTERNAL DEPOSIT RESULT IN THE TUBE BOWING AWAY FROM THE FURNACE AND LOW DRUM WATER LEVEL RESULTS BOWING TOWARDS THE FURNACE.

INTERNAL SCALE WILL CALL FOR INTERNAL CLEANING.INSPECT FOR DRUM DAMAGE OR TUBE SEAT LEKAGEPREVENT RECCURENCE OF LOW WATER CONDITION.