Burner Management System Presentation

Burner Management SystemGeneral guidelinesInterlock and ProtectionHardware architecture

What shall we look into, in todays session?NFPA guidelines

BMS requirements

BMS applications dealing withBoiler purge control

Fuel safety control (MFT)

Pre light-up control

Individual burner controlOil burnerCoal burner

BMS architecture

What is NFPA?NFPA is an abbreviation for National Fire Protection Association

Established in 1896, NFPA an international nonprofit membership organisation serves as the world's leading advocate of fire prevention and is an authoritative source on public safety

It is the authority on fire, electrical, and building safety.

Its mission is to reduce the worldwide burden of fire and other hazards on the quality of life by providing and advocating consensuscodes and standards,research,training, andeducation.

NFPA's 300 codes and standards influence building, process, service, design, and installation

NFPA Applicable standards for Boilers and FurnacesNFPA 85: Boiler and Combustion Systems Hazards Code, 2007 Edition.

PURPOSEThe standard provides minimum requirements for the design, installation, operation, and maintenance of large commercial and industrial boilers, heat recovery steam generators, and related combustion systems. These requirements help prevent fires, explosions, and implosions, and contribute to overall safety.

SCOPEThe standard covers structural design, purging systems, and fuel-burning systems, including fuel supplies , the main burner, combustion control systems, burner management systems, furnace pressure control systems, and other system and function requirements. Procedures for normal and emergency start-up and shut-down, fuel transfer, and firing of more than one fuel are also covered. Some requirements are specific to certain equipment applications.

NFPA Applicable standards for Boilers and Furnaces

NFPA 85 is a compilation of six earlier standards:NFPA 8501, Single-Burner Boiler Operation; NFPA 8502, Prevention of Furnace Explosions/ Implosions in MultipleBurner Boilers; NFPA 8503, Pulverized Fuel Systems, NFPA 8504, Atmospheric Fluidized-Bed Boiler Operation; NFPA 8505, Stoker Operation; and NFPA 8506, Heat-- Recovery Steam Generator Systems.

An excerpt from the above standard the basic cause of a furnace explosion is the ignition of an accumulated combustible mixture within the confined space of the furnace or the associated boiler passes, ducts, and fans that convey the gases of combustion to the stack.

Situations Causing Explosive conditions?Numerous situations can arise in connection with the operation of a boiler furnace that will produce explosive conditions.

Interruption of Fuel or air supply or ignition energy to the burners.

Fuel Leakage into an idle furnace and the ignition of the accumulation

Repeated Unsuccessful attempts to light up without appropriate purging

The Accumulation of an explosive mixture of fuel and air as a result of a complete furnace flameout

RequirementMultiple burner boilers require two independent control systems.

One to control steam production i.e. Boiler Control System and

One to control the fuel burning equipment i.e. Burner Management System

NFPA definitionNFPA defines

a Boiler Control System as The group of control systems that regulates the boiler process, including the combustion control system but not the burner management system. and

A Combustion Control System is The control system that regulates the furnace fuel and air inputs to maintain the air-fuel ratio within the limits that are required for continuous combustion and stable flame throughout the operating range of the boiler in accordance with demand .

NFPA definitionNFPA defines

a Burner Management System as The control system that is dedicated to combustion safety and operator assistance in the starting and stopping of fuel preparation and burning equipment and for preventing mal-operation of and damage to fuel preparation and burning equipment.

BMS What must it do?The Burner Management System

must be designed to ensure a safe, orderly operating sequence in the start-up and shutdown of fuel firing equipment and to reduce possible errors by following the operating procedure.

is intended to protect against malfunction of fuel firing equipment and associated systems.

In some phases of operation, the BMS shall provide permissive interlocks only to ensure safe startup of equipment. Once the equipment is in service, the operator must follow acceptable safe operating practices.

all parts of the BMS shall remain in good working order and in service whenever the burner is in service if the system is to provide the protection for which it is designed.

BMS - What are the basic Functions?The BMS shall be designed to perform the following functions:

Prevent firing unless a satisfactory furnace purge has first been completed.

Prohibit start-up of the equipment unless certain permissive interlocks have first been completed.

Monitor and control the correct component sequencing during start-up and shut-down of the equipment.

Provide component condition feedback to the operator and, if so equipped, to the plant control systems and/or data loggers.

Provide automatic supervision when the equipment is in service and provide means to make a Master Fuel Trip (MFT) should certain unacceptable firing conditions occur.

Execute a MFT upon certain adverse unit operating conditions.

How do we categorize the different controlsA Boiler Control System shall have the following applicationsCombustion controlExcess air controlSteam drum level controlA Burner Management System shall have the following applicationsBoiler purge controlFuel safety controlPre-light up controlIndividual burner control

Boiler Purge Control

Why: For removing all combustibles from the boiler furnace and replacing them with air to prevent any explosive mixture from remaining in the furnace prior to light up.

When: After a Master Fuel Trip has occurredHow: Ensuring that a predetermined set of fuel and air related permissive conditions are satisfied which shall includeAll fuel valves (Shut-off valves, oil valves) closedEither of one FD Fan & ID Fan running All Mills and Feeders stopped and Mill discharge valves closedAll PA Fans stopped and PA to Mill inlet dampers closedAll scanners sense no flameAir flow is not less than 25% - 35 % (multiple burner boilers) of full load air flow4 out of 6 secondary air dampers at Purge positionNo MFT conditions presentMFT relay tripped

Now the Boiler is Ready for Purge

Boiler Purge Control

Initiate Boiler PurgeDampers are initiated to move to Purge position (air flow 30 to 80 T/hr)5 minute purge timer triggersBoiler purge in progress is indicatedAfter 5 minutes has elapsed the Purge process is complete and the boiler is ready for firingIf any of the condition mentioned in A fails during purging process, purging is interrupted and the timer resets.

Fuel Safety ControlWhy: To prevent any explosive condition in the furnace

What: Withdraws fuel feed to the Furnace

When: If any of the predetermined trip conditions has occurred.

ClassificationDepending on the fuels involved the fuel safety control can be made up of the following:Master fuel tripOil fuel trip

Master Fuel TripIf any of the predetermined master fuel trip condition occurs a master fuel trip is initiated. The first out cause of trip indication is displayed and alarmed. Conditions of a master fuel trip are:

All FD Fans offAll ID Fans offBoiler air flow low for 3 secsLoss of all fuelLoss of all flameFurnace pressure very high/LowDrum level very high/lowCritical FlameoutDelayed light-upRe-heater protection operated

Master Fuel TripSome more Conditions of a master fuel trip (continued) :Loss of HT powerLoss of UPS powerLoss of 220V DC powerCondenser vacuum lowMFT hard relay tripped2 out of 3 main processors failedBoth emergency trip push buttons operatedAny of the above occasions will result in a MFT

MFT can be reset whenNone of the above trip conditions existBoiler purge is completeReset MFT is initiatedNEXT

MFT all FD fans offAll FD fans Off

Source : Breaker off signal from both fans

Implication: Will result in in-sufficient air for the combustion process and the fuel cannot burn

Action: MFT

MFT conditions

MFT all ID fans offAll ID fans Off

Source : Breaker off signal from all 3 fans

Implication: Will result in an uncontrolled furnace pressurization.

Action: MFT

MFT conditions

MFT Air flow less than 25%Boiler air flow less than < 25% for 3 secs

Source : Flow transmitters at FD suction

Implication: Will result in in-sufficient air for the combustion process and the fuel cannot burn completely

Action: MFT

MFT conditions

MFT Loss of all fuelLoss of all fuel

Source : Any oil burner in operation (MFT trip resets) and closure of all burner valves and all Mills off and no mill in shutdown mode.

Implication: As no fuel is being fed into the furnace generation of heat for sustenance of combustion and subsequent production of steam cannot take place

Action: MFTMFT conditions

MFT Loss of all flameLoss of all flame

Source : Any oil burner in operation and no scanners see flame.

Implication: Will proactively safeguard all adverse effect due to non burning of fuel (detected from the intensity of flame) being injected into the furnace


MFT Furnace pressure very high/lowFurnace pressure very high /low

Source : Pressure switch and transmitter.

Implication: Will result in explosion or implosion of the furnace resulting in mechanical deformity

Action: MFT

MFT conditions

MFT Drum level very high/lowDrum level very high / low

Source : Hydrastep and drum level transmitter

Implication: High: Will result in Flooding of superheaters causing a. carryover of dissolved solids and hence deposition downstream effecting heat transfer b. fall of steam temperature and quenching of Turbine

Low: Will result in starvation of water in the furnace tubes which will lead to tube metal overheating as no cooling medium is present


MFT Critical flameoutCritical Flameout

Source : Furnace flame scanners detect 2 out of 3 zones no flame

Implication: Is a consequence of improper combustion in pre-identified zones within the furnace resulting in flame instability which may give rise to improper heat distribution


MFT Delayed light-upDelayed light up

Source : MFT reset , LDO shut off valves open and no oil gun in operation (or in other words put into service) within 10 mins of opening of LDO shut-off valves.

Implication: Repeated unsuccessful attempts to light up the boiler with oil gun has resulted in accumulation of un-burnt fuel (oil) in the furnace and hence the furnace requires purging.


MFT Re-heater protectionRe-heater protection

Source : All governor valves closed, HP bypass valve < 2% open with a. at least one feeder running from remote or b. More than 8 out of 12 oil guns in operation

Implication: Damage to tubes that can result from firing in excess of safe limit which will cause overheating of re-heater tubes due to absence of a steam flow through it.

Action: MFT

MFT conditions

MFT Condenser Vacuum LowCondenser Vacuum LowSource : Pressure switch installed at condenser (500 mmHg abs)

Implication: Under turbine tripped condition and bypass in operation steam dumping continues at condenser which can result in pressurization. Under such poor vacuum conditions the condenser is not capable of dissipating the heat load with existing CW flow and with effect the temperature rises.

Action: MFT

MFT conditions

EFFECTS OF MFTMFT RELAY OPERATED

LDOT

HFOT

TRIP SEAL AIR FANS

TRIP ALL MILLS

TRIP ALL FEEDERS

CLOSE ALL ATTEMPERATION BLOCK VALVES

TRIP TURBINE

Oil Fuel TripIf any of the predetermined oil fuel trip conditions is exceeded the oil fuel trip is initiated. The first out cause of trip indication is displayed and alarmed. All oil fuel is removed from the boiler and all oil burners are shutdown. Depending on other conditions a master fuel trip may be generated. Conditions of an oil fuel trip are:

LDO trip valves close commandLDO trip valves not closed and LDOT condition is presentLDOT relay fail to trip and LDOT condition is presentLDO pressure very low for 3 secs and any LDO burner valves not closedAtomising air pressure very low for 3 secs and any LDO burner valves not closed LDO trip valve not open within 10 secs of LDOT resetAny burner valve fail to close despite boiler load being > 50%LDOT hard relay tripped

LDOT can be reset whenNone of the above trip conditions existMFT relay is resetTrip valve open is initiatedAll LDO burner valves are closed

Pre Light-up ControlWhy : To ensure all predetermined boiler LIGHT-UP conditions are satisfied prior to introducing any fuel in service.

When : Once the boiler purge has been completed and the master fuel trip has been reset.

How : It ensures that individual fuel and air conditions for pre lightup are satisfactory for igniter and burner operation, which shall include following checks and hence provide permission to light LDO,

LDO trip valves openLDOT resetLDO pressure healthyAtomizing air pressure healthy

Individual Burner ControlClassification of burners

Burner for gas firing nozzle type

Burner for oil firing sprayer plate type

Burner for coal firing gravity fed down shot fired, corner fired, front fired

Individual Burner Control - OilWhy : To ensure on light up a healthy flame is detected at the oil burner else burner is to be taken out of service ensuring no remnants of fuel in the burner

When : Once the permission to light LDO is given

How : It ensures that individual burner shall operate in 4 modes

Oil burner start permissivesOil burner light-upOil burner shutdownOil burner scavenging

Oil burner start permissivesThe following permissives are to be satisfied in order to proceed towards light-upPermission to light LDO is presentBurner LDO valve is closedNo flame is detected at burnerBurner shutdown condition is not initiatedBurner spark ignitor power healthy

This gives the Burner permission to start

Oil Burner Light-up : NotesNote 1:Burner Permission to start is presentBurner start PB operatedThis puts the burner in lighting mode

Note 2 :Atomising air valve openLDO valve openOil gun insertedOil flame detectedThese conditions indicate burner in operation

Oil Burner Light-upSequence of operationStep 1:Burner is in lighting modeBurner is not in operationFeeder is not running from remoteSecondary air dampers are initiated to move to oil position ( air flow 30 to 120 T/hr)Step 2:Burner is in lighting modeSecondary air dampers are in oil position or Feeder is running from remoteOil gun insertion initiatedStep 3:Burner is in lighting modeOil gun insertedAtomising air valve open initiated

Oil Burner Light-upSequence of operationStep 4:Burner is in lighting modeOil gun insertedAtomising air valve openScavenge valve closedSpark ignitor insertion initiated (and 15 secs timer triggered)

Step 5a:Burner is in lighting modeOil gun insertedAtomising air valve openScavenge valve closedSpark ignitor insertedEnergise spark ignitor

Oil Burner Light-upSequence of operationStep 5b:Burner is in lighting modeOil gun insertedAtomising air valve openScavenge valve closedSpark ignitor insertedLDO selected LDO valve open initiatedOil flame is detectedAfter 15 secs of ignitor insertion, command is withdrawn and hence ignitor retracts Burner Light up done

Oil Burner shutdownIf any of the predetermined conditions occurs a burner shutdown is initiated. It denies permission to start and resets lighting mode and as a result it closes atomising air valve and LDO valve, but oil gun remains inserted

Burner in lighting mode for 60 secs and oil gun not inserted Burner in lighting mode for 60 secs and LDO valve closedBurner in lighting mode for 60 secs and atomising air valve not full open LDO valve not closed and oil gun not insertedLDO valve neither full close for 15 secs nor full openLDO valve not closed for 10 secs and oil flame not detectedLDO valve not closed and scavenge valve not closedLDOTMFTAir flow < 10 %

Oil Burner ScavengingA condition which sees LDO valve close from open condition generates Burner oil gun scavenge required (resets when oil gun is retracted or LDO valve is not closed)

Sequence of operation

Step 1:Burner oil scavenge required persistsOil gun scavenge not blocked Indicates burner oil gun in scavenge mode

Step 2:Oil gun in scavenge modeOil gun insertedAtomising pressure healthySpark ignitor insertion initiated and 2 min timer triggered to start countdown of scavenge process

Step 3a:Spark ignitor insertedEnergise spark ignitor

Oil Burner ScavengingBurner oil gun scavenge is blocked when

MFTLDOTEither scavenge valve or atomising valve not full open when burner is in scavenge mode, oil gun is inserted, atomizing air pressure is healthy, ignitor is inserted and sparkingEither ignitor power is not available or ignitor not inserted when burner is in scavenge mode, oil gun is inserted, atomizing air pressure is healthy, Oil gun scavenge required persists and Atomizing air pressure not healthyOil gun scavenge required persists and Oil gun not insertedOil Burner stop command

The above conditions block scavenge mode

Oil Burner ScavengingSequence of operationStep 3b:Oil gun in scavenge modeOil gun insertedAtomising pressure healthySpark ignitor insertedSpark ignitor power availableScavenge valve open initiated

Step 4:Scavenge valve openStep 3b condition satisfiedAtomising air selectedAtomizing air valve open initiated

Oil Burner ScavengingSequence of operationStep 5:Atomizing air valve openScavenge valve openSpark ignitor insertedSpark ignitor power available2 mins has not elapsed since starting of scavenge processIndicates Burner oil gun purge/scavenge in progress

Step 6:Step 5 all conditions remaining except that 2 mins has elapsed since starting of scavenge processOil gun retract initiated

Oil Burner ScavengingSequence of operationStep 7:Oil gun retracted

Initiates scavenge valve to close, atomising air valve to close, de-energise spark ignitor, retract spark ignitor and simultaneously scavenge required message will disappear

Back to Individual Burner Control

Individual Burner Control - CoalWhy : To transfer the firing from oil to coal and attain a stable flame in the furnace at high loads

When : Once oil flame is detected, mill discharge valves are closed and PA to Mill inlet damper is closed

How : It ensures that individual burner shall operate in 6 modesMill start permissive and Mill startingOperation of Mill discharge valves Feeder startingFeeder normal shutdownMill normal shutdownPreferential Mill tripping

Mill Trip ConditionsThe following conditions shall cause a Mill to tripLOS or emergency stop pressedMill and feeder running from remote, oil flame not detected with either feeder speed 30 secs and PA flow below minimumMill running from remote for >30 secs and Secondary air flow < 45%Seal air pressure very lowMFT or Mill hard relay

Mill trip reset conditionsThe following conditions if satisfied will reset the Mill Trip Relay Oil flame is detected

Mill discharge valves are closed

PA to Mill inlet damper is closed

Note:Mill running from remote for 10 secs moves the secondary air dampers to PF position

Mill Start Permissive

The following conditions shall be satisfied prior to starting a MillNo mill trip condition present and Trip relay resetEither both PA fans running OR one PA fan running with less than 3 mills runningSelector switch in remote and breaker in serviceSeal air pressure healthyMill outlet temperature > 60C but < 110COil flame detectedMill discharge valve openMill lub oil pressure healthyMill loading gas pressure healthyPA to mill inlet damper closedThe above conditions gives the permissive to start a Mill and when Mill start is initiated from remote.. MILL STARTS provided Mill is not in shutdown mode

Mill discharge valve open and closeThe following conditions need to be true prior to opening a Mill Discharge ValveMill Trip relay resetOil flame detectedMDV not openSeal air pressure healthyThe above conditions gives the permissive to open Mill discharge valve and when Open is initiated .. MDV opensThe following conditions need to be true prior to closing a Mill Discharge ValveFeeder stoppedMill stoppedMDV openThe above conditions gives the permissive to close Mill discharge valve and when Close is initiated or MFT or Mill hard relay trip occurs.. MDV closes

Feeder StartingThe following conditions generates a start permissive for a FeederMill Trip relay resetOil flame detectedFeeder selected to remoteSeal air pressure healthyMill running from remoteFeeder selected in remoteMill secondary air dampers in PF position ( air flow 80 to 140 t/hr)Mill PA flow not below minimum (not less than 45 T/hr)Feeder trip condition not present and not running from remote

The above conditions gives the permissive to start a Feeder from remote and when start is initiated .. Feeder starts provided Feeder is not in shutdown mode

Certain points to noteThe following conditions generates a permission to shutdown oil burnersCoal flame has been detectedCoal flame is healthyFeeder is running from remote for more than 10 minsThe oil burners are now taken out of service

For providing support ignition the following conditions need to be trueCoal flame has been detectedCoal flame is not healthyFeeder is running from remoteThis generates an alarm Mill support ignition required and accordingly oil burners are to be put in service

Feeder Normal ShutdownThe following conditions generates a permission to stop a FeederOil flame detectedLDO valve open for both oil burnersFeeder running and speed at minimum

Either of the following conditions generates a trip condition for a Feeder and indicates Feeder in shutdown modePermission to stop Feeder persists, Feeder selected to remote, Stop feeder initiatedMFTMill Trip relayFeeder motor protection operated

Mill Normal ShutdownThe following conditions generates a permission to stop a MillMill running from remoteMill differential pressure lowORMill running from remoteOil flame detectedLDO valve openFeeder stoppedThe above condition need to persist for more than 5 mins to initiate a permission to stop a Mill . It signifies Mill is empty.

Either of the following conditions below de-energize Mill hard relay and indicates Mill in shutdown modeMill is empty, Mill selected to remote, Stop Mill initiated. Inhibits oil burner shutdown until Mill outlet temperature is < 60C and mill is stoppedMFTMill Trip relay

Mill Seal Air valve Open / CloseEither of the following conditions will result in opening of Mill Seal Air ValveMill Trip relay resetPA to Mill inlet damper not closedOpen Seal air valve initiatedProvided no Seal air valve close signal persists

Either of the following conditions will result in closing a Mill Seal Air ValveMill trip relay trippedMill stopped and close seal air valve command initiatedProvided PA to Mill inlet damper open does not persist

Preferential Mill TrippingWhy : To take out certain running Mills out of service as per preference in order to reduce firing and compensate for the furnace conditions prevailing

When : On Turbine tripLoad rejection >50 %Single FD or PA fan running

How : It ensures that extreme burners shall tripUnder 4 mill condition if Mill D is not in service then Mill A tripsIf Mill A is not in service then Mill D tripsIf both Mill A and Mill D are in service, Mill A trips if Mill D is the single Mill in the rear OR Mill D trips if Mill A is the single Mill in the frontIf Mill A and Mill D both are not in service then Mill B tripsUnder 5 mill conditionMill A and Mill D trips if they are both in service Mill A and Mill B trips if Mill D is not in serviceMill B and Mill D trips if Mill A is not in service

Hardware - PLCEFFECTIVE AND RELIABLE SYSTEM FOR OVERALL SUPERVISION OF BOILER SAFETY IN A POWER PLANT.CONTAINS SAFETY GUIDELINES PROGRAMMED INSIDE FORTAKING PREVENTIVE MEASURESIN EXTREME CASES TO TAKE THE WHOLE SYSTEM TO STEP-BY-STEP SHUTDOWN.IT FORESEES FUTURE ERROR AND GENERATE ALARMS.BMS IS THE SUPPORTIVE SYSTEM WITH THE DCS TO MANAGE THE PLANT IN SIMPLER WAY.Transferring control to Fault Tolerant pair and running self diagnosticsRunning self diagnostics and monitoringChassis with Processor and I/O cards

Hardware - PLCTHE BMS IS A PLC, PROGRAMMED ACCORDING TO USER NEED.LIKE CONVENTIONAL PLC SYSTEMS THE BMS ALSO CONSISTS OF THE FOLLOWING PARTS:-MOUNTING RACK FOR HOUSING THE WHOLE PLC SYSTEM.POWER SUPPLY FOR SUPPLYING POWER TO THE PLC SYSTEM.MAIN PROCESSOR THE BRAIN OF THE SYSTEMI/O CARDS INTERFACING UNITS BETWEEN SYSTEM & FIELDSPECIAL MODULES COMMUNICATION WITH OTHER SYSTEMS, ETC.SPECIAL FUNCTIONS HIGH SPEED COUNTER, THERMOCOUPLE SENSORS (NOT IN BBGS)

What is TMR architecture?

It means Triple Modular RedundantTMR architecture integrates three isolated parallel control systems ( as evident in diagram)Extensive diagnostics carried out in each Control SystemThe system uses TWO-OUT-OF-THREE voting to provide high integrity, error free uninterrupted process operation with no single point failure

WHAT ARE THE KEY FEATURES?

The Tricon controller uses three identical channels to process single data from field

Each channel independently and parallely executes the application program which can remain in the form of Ladder Logic, Functional Block Diagram or Statement List in the processors

Specialised hardware / software voting mechanisms qualify and verify digital inputs / outputs from / to field

Analog inputs are subjected to a MEDIAN VALUE selection

Each channel is isolated from the others and no single point failure in any channel can pass to another channel

LoopbackInputLegBInputLegCMain Processor BMain Processor AMain Processor COutputLegAOutputLegBOutputLegCLoopbackCBA+V A BInputLegATMR Architecture

Terminology and buzz wordsFault TolerantThe Ability of the System to Continue to Perform its Function in the Presence of Faults and Errors.No Single Point of Failure will Shutdown the SystemFail-SafeIf the System does Fail it will Fail to the Safe State or the state of the Equipment Under Control (EUC) when safety is achieved - de-energized for ESD SystemsPFD - Probability-to-Fail On Demand AvailabilityThe probability that the system will be operational at some instant of time

WHAT ARE THE KEY FEATURES?

Diagnostic FeaturesInput card checks for stuck on points

Output card checks for output voter diagnostic 2OO3 voting

Processor checks for faults at input and output modules as well as itself and generates appropriate alarms for corrective action

Documents

Burner Management System Presentation