BOILER CONTROLS &BOILER CONTROLS & … Control and instruments... · Boiler will trip if instrument air pressure fails. BURNER MANAGEMENT SYSTEM NATIONAL FIRE PROTECTION ACT ( NFPA)NATIONAL

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BOILER CONTROLS & BOILER CONTROLS & INSTRUMENTATIONINSTRUMENTATION

PRESENTED ATPRESENTED ATPRESENTED AT PRESENTED AT M/S. MAGADI SODA COMPANY , M/S. MAGADI SODA COMPANY ,

MAGADI KENYAMAGADI KENYAMAGADI , KENYAMAGADI , KENYA

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THERMODYNE THERMODYNE TECHNOLOGIES PRIVATE TECHNOLOGIES PRIVATE

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MAJOR CLOSED LOOP CONTROLS IN BOILERMAJOR CLOSED LOOP CONTROLS IN BOILER

DRUM LEVEL CONTROLDRUM LEVEL CONTROL•• PUMP ONPUMP ON--OFF CONTROL ( USED ON OFF CONTROL ( USED ON ((

PACKAGED SATURATED STEAM BOILERS)PACKAGED SATURATED STEAM BOILERS)•• SINGLE ELEMENT DRUM LEVEL CONTROL SINGLE ELEMENT DRUM LEVEL CONTROL

( USED IN SMALL & PACKAGE BOILERS WITH ( USED IN SMALL & PACKAGE BOILERS WITH ECONOMISERS OPERATING AT LOW ECONOMISERS OPERATING AT LOW PRESSURE)PRESSURE)PRESSURE)PRESSURE)

•• THREE ELEMENT DRUM LEVEL CONTROL ( THREE ELEMENT DRUM LEVEL CONTROL ( USED IN HIGH PRESSURE LARGE CAPACITYUSED IN HIGH PRESSURE LARGE CAPACITYUSED IN HIGH PRESSURE LARGE CAPACITY USED IN HIGH PRESSURE LARGE CAPACITY BOILERS )BOILERS )

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SINGLE ELEMENT DRUM LEVEL CONTROLSINGLE ELEMENT DRUM LEVEL CONTROL

IN A SINGLE ELEMENT CONTROL , THE IN A SINGLE ELEMENT CONTROL , THE LEVEL TRANSMITTER ON THE STEAM LEVEL TRANSMITTER ON THE STEAM DRUM WILL TRANSMIT THE LEVEL DRUM WILL TRANSMIT THE LEVEL SIGNAL TO THE CONTROLLER. LEVEL SIGNAL TO THE CONTROLLER. LEVEL CONTROLLER COMPARES THIS SIGNALCONTROLLER COMPARES THIS SIGNALCONTROLLER COMPARES THIS SIGNAL CONTROLLER COMPARES THIS SIGNAL WITH THE SET POINT AND SENDS AN WITH THE SET POINT AND SENDS AN OUTPUT SIGNAL TO THE FEED WATEROUTPUT SIGNAL TO THE FEED WATEROUTPUT SIGNAL TO THE FEED WATER OUTPUT SIGNAL TO THE FEED WATER CONTROL VALVE TO OPEN OR CLOSE CONTROL VALVE TO OPEN OR CLOSE TO INCREASE OR DECREASE THE FEEDTO INCREASE OR DECREASE THE FEEDTO INCREASE OR DECREASE THE FEED TO INCREASE OR DECREASE THE FEED WATER FLOW TO THE BOILER.WATER FLOW TO THE BOILER.

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SINGLE ELEMENT DRUM LEVEL CONTROLSINGLE ELEMENT DRUM LEVEL CONTROL

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WHY THREE ELEMENT CONTROL ?WHY THREE ELEMENT CONTROL ?IN HIGH PRESSURE BOILERS , WHEN THE IN HIGH PRESSURE BOILERS , WHEN THE ,,STEAM DEMAND OF THE BOILER INCREASES STEAM DEMAND OF THE BOILER INCREASES SUDDENLY , THE WITHDRAWAL OF STEAM SUDDENLY , THE WITHDRAWAL OF STEAM FROM THE STEAM DRUM WILL BE HIGHERFROM THE STEAM DRUM WILL BE HIGHERFROM THE STEAM DRUM WILL BE HIGHER FROM THE STEAM DRUM WILL BE HIGHER THAN THE STEAM GENERATION AS THAN THE STEAM GENERATION AS COMBUSTION CONTROL WILL TAKE SOME COMBUSTION CONTROL WILL TAKE SOME TIME TO REACT AND INCREASE THE FUEL TIME TO REACT AND INCREASE THE FUEL HEAT INPUT TO THE BOILER.THIS WILL HEAT INPUT TO THE BOILER.THIS WILL RESULT IN DRUM PRESSURE FALLINGRESULT IN DRUM PRESSURE FALLINGRESULT IN DRUM PRESSURE FALLING RESULT IN DRUM PRESSURE FALLING TEMPORARILY. THIS LOSS OF PRESSURE TEMPORARILY. THIS LOSS OF PRESSURE WILL RESULT IN THE FORMATION OF STEAM WILL RESULT IN THE FORMATION OF STEAM BUBBLES IN THE DRUM WATER DUE TO THE BUBBLES IN THE DRUM WATER DUE TO THE ENTHAPHY DIFFERENCE BETWEEN THE TWO ENTHAPHY DIFFERENCE BETWEEN THE TWO PRESSURE LEVELSPRESSURE LEVELS

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PRESSURE LEVELS.PRESSURE LEVELS.

WHY THREE ELEMENT CONTROL ?WHY THREE ELEMENT CONTROL ?CONTINUEDCONTINUED

THIS BUBBLING IN THE DRUM WATER WILL THIS BUBBLING IN THE DRUM WATER WILL RESULT IN THE FOAMING AND INCREASE IN RESULT IN THE FOAMING AND INCREASE IN THE VOLUME LEADING TO THE LEVEL GOINGTHE VOLUME LEADING TO THE LEVEL GOINGTHE VOLUME LEADING TO THE LEVEL GOING THE VOLUME LEADING TO THE LEVEL GOING UP SPURIOUSLY. THE LEVEL TRANSMITTER UP SPURIOUSLY. THE LEVEL TRANSMITTER WILL TRANSMIT THIS INCREASE IN DRUMWILL TRANSMIT THIS INCREASE IN DRUMWILL TRANSMIT THIS INCREASE IN DRUM WILL TRANSMIT THIS INCREASE IN DRUM LEVEL TO THE CONTROLLER LEADING TO LEVEL TO THE CONTROLLER LEADING TO REDUCTION IN FEED WATER FLOW INSTEAD REDUCTION IN FEED WATER FLOW INSTEAD OF INCREASING THE FEED WATER FLOW OF INCREASING THE FEED WATER FLOW DUE TO HIGHER DEAMND ON BOILER. TO DUE TO HIGHER DEAMND ON BOILER. TO AVOID SUCH A WRONG CONTROL 3 ELEMENTAVOID SUCH A WRONG CONTROL 3 ELEMENTAVOID SUCH A WRONG CONTROL 3 ELEMENT AVOID SUCH A WRONG CONTROL 3 ELEMENT DRUM LEVEL CONTROL IS REQUIREDDRUM LEVEL CONTROL IS REQUIRED

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THREE ELEMENT DRUM LEVEL CONTROLTHREE ELEMENT DRUM LEVEL CONTROL

IN THIS THE DRUM LEVEL CONTROLLER IN IN THIS THE DRUM LEVEL CONTROLLER IN ADDITION TO RECEIVING THE DRUM LEVEL ADDITION TO RECEIVING THE DRUM LEVEL SIGNAL WILL ALSO RECEIVE THE STEAMSIGNAL WILL ALSO RECEIVE THE STEAMSIGNAL , WILL ALSO RECEIVE THE STEAM SIGNAL , WILL ALSO RECEIVE THE STEAM FLOW AND FEED WATER FLOW FLOW AND FEED WATER FLOW TRANSMITTER SIGNALS. HENCE WHENEVER TRANSMITTER SIGNALS. HENCE WHENEVER THERE IS A DIFFERENCE BETWEEN THETHERE IS A DIFFERENCE BETWEEN THETHERE IS A DIFFERENCE BETWEEN THE THERE IS A DIFFERENCE BETWEEN THE STEAM AND WATER FLOW , THE STEAM AND WATER FLOW , THE CONTROLLER WILL APPLY SUITABLECONTROLLER WILL APPLY SUITABLECONTROLLER WILL APPLY SUITABLE CONTROLLER WILL APPLY SUITABLE CORRECTION TO ITS OUTPUT SIGNAL TO THE CORRECTION TO ITS OUTPUT SIGNAL TO THE FEED CONTROL VALVE. THIS TYPE OF FEED CONTROL VALVE. THIS TYPE OF CONTROL WILL KEEP THE DRUM LEVELCONTROL WILL KEEP THE DRUM LEVELCONTROL WILL KEEP THE DRUM LEVEL CONTROL WILL KEEP THE DRUM LEVEL CONTROL TO FUNCTION CORRECTLY EVEN CONTROL TO FUNCTION CORRECTLY EVEN WHEN THE BOILER LOAD CHANGESWHEN THE BOILER LOAD CHANGES

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O O C G SO O C G S

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FLOW COMPENSATIONSFLOW COMPENSATIONSIN CASE OF FLOW MEASUREMENTS FOR IN CASE OF FLOW MEASUREMENTS FOR CO SS S ( S G S )CO SS S ( S G S )COMPRESSIBLE FLUIDS ( STEAM , GAS ) , THE COMPRESSIBLE FLUIDS ( STEAM , GAS ) , THE DENSITY WILL CHANGE DUE TO CHANGE IN DENSITY WILL CHANGE DUE TO CHANGE IN PRESSURE AND TEMPERATURE OF THE PRESSURE AND TEMPERATURE OF THE MEDIUM. IN SUCH CASES BOTH THE PRESSURE MEDIUM. IN SUCH CASES BOTH THE PRESSURE AND TEMPERATURE OF THE FLUID ALSO SHALL AND TEMPERATURE OF THE FLUID ALSO SHALL BE MEASURED TO APPLY THE DENSITYBE MEASURED TO APPLY THE DENSITYBE MEASURED TO APPLY THE DENSITY BE MEASURED TO APPLY THE DENSITY CORRECTION FOR THE FLOW MEASUREMENTS. CORRECTION FOR THE FLOW MEASUREMENTS. FOR EXAMPLE IN A THREE ELEMENT DRUM FOR EXAMPLE IN A THREE ELEMENT DRUM LEVEL CONTROL THE CONTROLLER WILL ALSOLEVEL CONTROL THE CONTROLLER WILL ALSOLEVEL CONTROL , THE CONTROLLER WILL ALSO LEVEL CONTROL , THE CONTROLLER WILL ALSO NEED THE STEAM PRESSURE AND NEED THE STEAM PRESSURE AND TEMPERATURE SIGNALS TO CORRECT THE TEMPERATURE SIGNALS TO CORRECT THE STEAM FLOW. WITHOUT THIS THE CONTROL STEAM FLOW. WITHOUT THIS THE CONTROL WILL GO WRONG.WILL GO WRONG.

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SUPER HEATER STEAM TEMPERATURE SUPER HEATER STEAM TEMPERATURE CONTROLCONTROL

IN BOILERS WITH HIGH SUPER HEAT IN BOILERS WITH HIGH SUPER HEAT TEMPERATURES IT IS NECESSARY TO PROTECT TEMPERATURES IT IS NECESSARY TO PROTECT THE DOWN STREAM EQUIPMENT LIKE STEAMTHE DOWN STREAM EQUIPMENT LIKE STEAMTHE DOWN STREAM EQUIPMENT LIKE STEAM THE DOWN STREAM EQUIPMENT LIKE STEAM TURBINE FROM LARGE VARIATION IN TURBINE FROM LARGE VARIATION IN TEMPERATURES. ALSO WITHIN THE BOILER TEMPERATURES. ALSO WITHIN THE BOILER CONTROL RANGE( NORMALLY 60 TO 100 % MCR)CONTROL RANGE( NORMALLY 60 TO 100 % MCR)CONTROL RANGE( NORMALLY 60 TO 100 % MCR), CONTROL RANGE( NORMALLY 60 TO 100 % MCR), THE STEAM TEMPERATURE LEAVING THE THE STEAM TEMPERATURE LEAVING THE BOILER IS REQUIRED TO BE MAINTAINED BOILER IS REQUIRED TO BE MAINTAINED CONSTANT IN MANY APPLICATIONS. IN CONSTANT IN MANY APPLICATIONS. IN INDUSTRIAL BOILERS THE SUPER HEATERS ARE INDUSTRIAL BOILERS THE SUPER HEATERS ARE GENERALLY CONVECTIVE TYPE AND HENCE ITS GENERALLY CONVECTIVE TYPE AND HENCE ITS HEAT ABSORPTION WILL GO DOWN WITH BOILER HEAT ABSORPTION WILL GO DOWN WITH BOILER LOAD AND THUS GAS FLOW.LOAD AND THUS GAS FLOW.

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SUPER HEATER STEAM TEMPERATURE SUPER HEATER STEAM TEMPERATURE CONTROLCONTROL--CONTINUEDCONTINUEDCONTROLCONTROL CONTINUEDCONTINUED

HENCE THE SUPER HEATER WILL BE SIZED TO GIVE HENCE THE SUPER HEATER WILL BE SIZED TO GIVE REQUIRED STEAM TEMPERATURE AT THE MINIMUM REQUIRED STEAM TEMPERATURE AT THE MINIMUM OF THE CONTROL LOAD AND AT FULL LOAD IF NOTOF THE CONTROL LOAD AND AT FULL LOAD IF NOTOF THE CONTROL LOAD AND AT FULL LOAD , IF NOT OF THE CONTROL LOAD AND AT FULL LOAD , IF NOT CONTROLLED ,THE SUPER HEATER OUTLET CONTROLLED ,THE SUPER HEATER OUTLET TEMPERATURE WILL BE MUCH HIGHER THAN TEMPERATURE WILL BE MUCH HIGHER THAN REQUIRED HENCE SUPER HEATER STEAMREQUIRED HENCE SUPER HEATER STEAMREQUIRED. HENCE SUPER HEATER STEAM REQUIRED. HENCE SUPER HEATER STEAM TEMPERATURE CONTROL IS REQUIRED TEMPERATURE CONTROL IS REQUIRED ESSENTIALLY. THE SUPER HEATER OUTLET ESSENTIALLY. THE SUPER HEATER OUTLET TEMPERATURE IS SENT TO THE CONTROLLER BYTEMPERATURE IS SENT TO THE CONTROLLER BYTEMPERATURE IS SENT TO THE CONTROLLER BY TEMPERATURE IS SENT TO THE CONTROLLER BY THE TEMPERATURE TRANSMITTER. THE THE TEMPERATURE TRANSMITTER. THE CONTROLLERS COMPARES THE SAME WITH THE SET CONTROLLERS COMPARES THE SAME WITH THE SET POINT AND GIVES A RESULTANT SIGNAL TO THEPOINT AND GIVES A RESULTANT SIGNAL TO THEPOINT AND GIVES A RESULTANT SIGNAL TO THE POINT AND GIVES A RESULTANT SIGNAL TO THE SPARY CONTROL VALVE TO CHANGE THE SPRAY SPARY CONTROL VALVE TO CHANGE THE SPRAY WATER QUANTITY WATER QUANTITY

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BALANCED DRAFT CONTROLBALANCED DRAFT CONTROLIN BOILERS PROVIDED WITH BOTH FD AND IDIN BOILERS PROVIDED WITH BOTH FD AND IDIN BOILERS PROVIDED WITH BOTH FD AND ID IN BOILERS PROVIDED WITH BOTH FD AND ID FANS IT IS NECESSARY TO MAINTAIN THE FANS IT IS NECESSARY TO MAINTAIN THE FURNACE DRAFT AT NEAR ZERO PRESSURE. FURNACE DRAFT AT NEAR ZERO PRESSURE. ( BETWEEN ( BETWEEN ––5 TO 5 TO ––10 MMWC TO PREVENT 10 MMWC TO PREVENT FLAME FROM COMING OUT AND INJURING FLAME FROM COMING OUT AND INJURING OPERATING PERSONNEL ) THIS IS DONE BY THISOPERATING PERSONNEL ) THIS IS DONE BY THISOPERATING PERSONNEL ) THIS IS DONE BY THIS OPERATING PERSONNEL ) THIS IS DONE BY THIS CONTROL. THE FURNACE DRAFT TRANSMITTER CONTROL. THE FURNACE DRAFT TRANSMITTER SENDS THE FURNACE DRAFT SIGNAL TO THE SENDS THE FURNACE DRAFT SIGNAL TO THE CONTROLLER CONTROLLER ON COMPARINGCONTROLLER CONTROLLER ON COMPARINGCONTROLLER. CONTROLLER ON COMPARING CONTROLLER. CONTROLLER ON COMPARING THE SAME WITH THE SET POINT SENDS AN THE SAME WITH THE SET POINT SENDS AN OUTPUT SIGNAL TO THE PNEUMATIC POWER OUTPUT SIGNAL TO THE PNEUMATIC POWER CYLINDER OF THE ID FAN DAMPER TO OPEN ORCYLINDER OF THE ID FAN DAMPER TO OPEN ORCYLINDER OF THE ID FAN DAMPER TO OPEN OR CYLINDER OF THE ID FAN DAMPER TO OPEN OR CLOSE THE SAME AND THUS CONTROLS THE CLOSE THE SAME AND THUS CONTROLS THE FURNACE PRESSURE WITHIN LIMITS.FURNACE PRESSURE WITHIN LIMITS.

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COMBUSTION CONTROLCOMBUSTION CONTROLTHE STEAM DEMAND FROM BOILER VARYTHE STEAM DEMAND FROM BOILER VARYTHE STEAM DEMAND FROM BOILER VARY THE STEAM DEMAND FROM BOILER VARY DEPENDING UPON CHANGE IN PROCESS DEPENDING UPON CHANGE IN PROCESS REQUIREMENT OR POWER REQUIREMENT. THE FUEL REQUIREMENT OR POWER REQUIREMENT. THE FUEL FED TO THE BOILER SHOULD BE CONTROLLED TOFED TO THE BOILER SHOULD BE CONTROLLED TOFED TO THE BOILER SHOULD BE CONTROLLED TO FED TO THE BOILER SHOULD BE CONTROLLED TO GIVE THE NECESSARY QUANTITY OF STEAM. THE GIVE THE NECESSARY QUANTITY OF STEAM. THE STEAM DEMAND INCREASE OR DECREASE WILL BE STEAM DEMAND INCREASE OR DECREASE WILL BE INDICATED BY THE BOILER OUTLET PRESSUREINDICATED BY THE BOILER OUTLET PRESSUREINDICATED BY THE BOILER OUTLET PRESSURE. INDICATED BY THE BOILER OUTLET PRESSURE. HENCE COMBUSTION CONTROL IS ESSENTIALLY A HENCE COMBUSTION CONTROL IS ESSENTIALLY A CONTROL TO KEEP THE BOILER OUTLET PRESSURE CONTROL TO KEEP THE BOILER OUTLET PRESSURE CONSTANT THE STEAM PRESSURE TRANSMITTER INCONSTANT THE STEAM PRESSURE TRANSMITTER INCONSTANT. THE STEAM PRESSURE TRANSMITTER IN CONSTANT. THE STEAM PRESSURE TRANSMITTER IN THE MAIN STEAM LINE SENDS THE SIGNAL TO THE THE MAIN STEAM LINE SENDS THE SIGNAL TO THE CONTROLLER WHICH IN TURN SENDS AN OUTPUT CONTROLLER WHICH IN TURN SENDS AN OUTPUT SIGNAL TO THE FEEDER MOTORS IN THE SOLID FUELSIGNAL TO THE FEEDER MOTORS IN THE SOLID FUELSIGNAL TO THE FEEDER MOTORS IN THE SOLID FUEL SIGNAL TO THE FEEDER MOTORS IN THE SOLID FUEL FIRED BOILERS AND TO THE FUEL CONTROL VALVE FIRED BOILERS AND TO THE FUEL CONTROL VALVE IN THE CASE OF OIL AND GAS FIRED BOILERS.IN THE CASE OF OIL AND GAS FIRED BOILERS.

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COMBUSTION CONTROL COMBUSTION CONTROL -- CONTINUEDCONTINUEDCOMBUSTION CONTROL IN OIL AND GASCOMBUSTION CONTROL IN OIL AND GASCOMBUSTION CONTROL IN OIL AND GAS COMBUSTION CONTROL IN OIL AND GAS FIRED BOILERS CAN BE VERY ACCURATE AS FIRED BOILERS CAN BE VERY ACCURATE AS IT IS EASY TO MEASURE THE FUEL FLOW IT IS EASY TO MEASURE THE FUEL FLOW ACCURATELY . HOWEVER IN SOLID FUEL ACCURATELY . HOWEVER IN SOLID FUEL FIRED BOILERS , THE FUEL CONTROL IS FIRED BOILERS , THE FUEL CONTROL IS MORE VOLUMETRIC AND NOT WEIGHT BASISMORE VOLUMETRIC AND NOT WEIGHT BASISMORE VOLUMETRIC AND NOT WEIGHT BASIS. MORE VOLUMETRIC AND NOT WEIGHT BASIS. IT IS ASSUMED THAT THE DENSITY OF THE IT IS ASSUMED THAT THE DENSITY OF THE FUEL IS CONSTANT AND THE FEEDER IS FUEL IS CONSTANT AND THE FEEDER IS FULLY FILLED WITHOUT VACCUM . BOTH FULLY FILLED WITHOUT VACCUM . BOTH THESE ASSUMPTIONS ARE NOT EAXCTLY THESE ASSUMPTIONS ARE NOT EAXCTLY CORRECT IN MANY SMALL SOLID FUELCORRECT IN MANY SMALL SOLID FUELCORRECT. IN MANY SMALL SOLID FUEL CORRECT. IN MANY SMALL SOLID FUEL FIRED INDUSTRIAL BOILERS THIS CONTROL FIRED INDUSTRIAL BOILERS THIS CONTROL IS NOT AUTOMATIC BUT MANUAL.IS NOT AUTOMATIC BUT MANUAL.

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COMBUSTION CONTROL COMBUSTION CONTROL -- CONTINUEDCONTINUEDEVEN WHERE THE FUEL CONTROL ISEVEN WHERE THE FUEL CONTROL ISEVEN WHERE THE FUEL CONTROL IS EVEN WHERE THE FUEL CONTROL IS AUTOMATIC , THE AIR FLOW CONTROL WILL AUTOMATIC , THE AIR FLOW CONTROL WILL BE SEMIBE SEMI--AUTOMATIC. THE FD FAN GUIDE AUTOMATIC. THE FD FAN GUIDE SS U O C GUU O C GUVANE/DAMPER WILL BE CONTROLLED VANE/DAMPER WILL BE CONTROLLED REMOTE MANUALLY BY THE OPERATOR TO REMOTE MANUALLY BY THE OPERATOR TO MATCH THE FUEL FLOW ONLY IN VERYMATCH THE FUEL FLOW ONLY IN VERYMATCH THE FUEL FLOW. ONLY IN VERY MATCH THE FUEL FLOW. ONLY IN VERY LARGE BOILERS , THE AIR FLOW CONTROL LARGE BOILERS , THE AIR FLOW CONTROL ALSO WILL BE AUTOMATIC , WITH THE SAME ALSO WILL BE AUTOMATIC , WITH THE SAME ,,SIGNAL FROM STEAM PRESSURE SIGNAL FROM STEAM PRESSURE CONTROLLER GOING TO THE ACTUATOR OF CONTROLLER GOING TO THE ACTUATOR OF THE FD FAN DAMPER AFTER GETTINGTHE FD FAN DAMPER AFTER GETTINGTHE FD FAN DAMPER AFTER GETTING THE FD FAN DAMPER AFTER GETTING CORRECTED TO THE ACTUAL AIR FLOW CORRECTED TO THE ACTUAL AIR FLOW SIGNAL RECEIVED FROM THE AIR FLOW SIGNAL RECEIVED FROM THE AIR FLOW

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TRANSMITTER.TRANSMITTER.

DEAERATOR CONTROLSDEAERATOR CONTROLSDEAERATORS NORMALLY HAVE TWO CONTROLS :DEAERATORS NORMALLY HAVE TWO CONTROLS :DEAERATORS NORMALLY HAVE TWO CONTROLS :DEAERATORS NORMALLY HAVE TWO CONTROLS :

•• PRESSURE CONTROLPRESSURE CONTROLTHIS IS NECESSARY TO MAINTAIN THETHIS IS NECESSARY TO MAINTAIN THETHIS IS NECESSARY TO MAINTAIN THE THIS IS NECESSARY TO MAINTAIN THE DEAERATION TEMPERATURE AT THE REQUIRED DEAERATION TEMPERATURE AT THE REQUIRED LEVEL TO ACHIVE THE REMOVAL OF GASES FROM LEVEL TO ACHIVE THE REMOVAL OF GASES FROM WATER. SINCE IN SATURATED CONDITIONS BOTH WATER. SINCE IN SATURATED CONDITIONS BOTH PRESSURE AND TEMPERATURE ARE RELATED , PRESSURE AND TEMPERATURE ARE RELATED , THE DEAEARATOR PRESSURE IS CONTROLLEDTHE DEAEARATOR PRESSURE IS CONTROLLEDTHE DEAEARATOR PRESSURE IS CONTROLLED THE DEAEARATOR PRESSURE IS CONTROLLED INSTEAD OF THE TEMPERATURE.INSTEAD OF THE TEMPERATURE.

•• LEVEL CONTROLLEVEL CONTROLLEVEL CONTROLLEVEL CONTROLTHE DEAERATOR LEVEL CONTROL IS SIMILAR TO THE DEAERATOR LEVEL CONTROL IS SIMILAR TO THE SINGLE ELEMENT DRUM LEVEL CONTROL.THE SINGLE ELEMENT DRUM LEVEL CONTROL.

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BOILER INTERLOCKSBOILER INTERLOCKSIN ADDITION TO CLOSED LOOP FULLY MODULATING CONTROLS IN ADDITION TO CLOSED LOOP FULLY MODULATING CONTROLS REQUIRED FOR THE NORMAL OPERATION OF THE BOILERREQUIRED FOR THE NORMAL OPERATION OF THE BOILERREQUIRED FOR THE NORMAL OPERATION OF THE BOILER , REQUIRED FOR THE NORMAL OPERATION OF THE BOILER , INTERLOCK CONTROLS ARE REQUIRED FOR THE SAFE STARTINTERLOCK CONTROLS ARE REQUIRED FOR THE SAFE START--UP AND SHUTUP AND SHUT--DOWN OF THE BOILER.DOWN OF THE BOILER.THE FOLLOWING ARE SOME OF THE INTERLOCKS USED FORTHE FOLLOWING ARE SOME OF THE INTERLOCKS USED FORTHE FOLLOWING ARE SOME OF THE INTERLOCKS USED FOR THE FOLLOWING ARE SOME OF THE INTERLOCKS USED FOR SOLID FUEL FIRED BOILERS. SOLID FUEL FIRED BOILERS. 1.1. FD fan can not start without ID fan FD fan can not start without ID fan 22 Fuel flow will not start without FD and ID fansFuel flow will not start without FD and ID fans2.2. Fuel flow will not start without FD and ID fansFuel flow will not start without FD and ID fans

are in operationare in operation3.3. Standby feed pump will automatically come intoStandby feed pump will automatically come into

operation when operating pump failsoperation when operating pump failsoperation when operating pump failsoperation when operating pump fails4.4. Boiler will trip in case of steam drum low levelBoiler will trip in case of steam drum low level

trip switch is activatedtrip switch is activated55 Boiler will trip if Deaerator low low level switch isBoiler will trip if Deaerator low low level switch is5.5. Boiler will trip if Deaerator low low level switch isBoiler will trip if Deaerator low low level switch is

activatedactivated6.6. Boiler will trip is ID fan tripsBoiler will trip is ID fan trips77 Boiler will trip if instrument air pressure failsBoiler will trip if instrument air pressure fails

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7.7. Boiler will trip if instrument air pressure fails.Boiler will trip if instrument air pressure fails.

BURNER MANAGEMENT SYSTEMBURNER MANAGEMENT SYSTEMNATIONAL FIRE PROTECTION ACT ( NFPA)NATIONAL FIRE PROTECTION ACT ( NFPA)NATIONAL FIRE PROTECTION ACT ( NFPA) , NATIONAL FIRE PROTECTION ACT ( NFPA) , USA IS WIDELY USED ALL OVER THE WORLD USA IS WIDELY USED ALL OVER THE WORLD WITH REGARD TO THE INTERLOCKSWITH REGARD TO THE INTERLOCKSWITH REGARD TO THE INTERLOCKS WITH REGARD TO THE INTERLOCKS REQUIRED FOR SAFE STARTREQUIRED FOR SAFE START--UP AND SHUTUP AND SHUT--DOWN OF OIL AND GAS FIRED BURNERS.DOWN OF OIL AND GAS FIRED BURNERS.O O O G S U SO O O G S U STHESE INTERLOCKS ARE TO BE HANDLED BY THESE INTERLOCKS ARE TO BE HANDLED BY A SEPARATE PROCESSOR IN THE PLC/DCS A SEPARATE PROCESSOR IN THE PLC/DCS AS PER NFPA AND NOT BY THE SAME AS PER NFPA AND NOT BY THE SAME PROCESSOR WHICH HANDLES THE OTHER PROCESSOR WHICH HANDLES THE OTHER BOILER OPEN LOOP OR CLOSED LOOP BOILER OPEN LOOP OR CLOSED LOOP CONTROLS.CONTROLS.

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BURNER MANAGEMENT SYSTEM BURNER MANAGEMENT SYSTEM -- CONTINUEDCONTINUEDSOME OF THE STARTSOME OF THE START UP PERMISSIVESUP PERMISSIVESSOME OF THE STARTSOME OF THE START--UP PERMISSIVESUP PERMISSIVES1.1. Oil pressure is not lowOil pressure is not low22 Oil temperature is not lowOil temperature is not low2.2. Oil temperature is not lowOil temperature is not low3.3. Fuel gas pressure is not lowFuel gas pressure is not low44 Fuel gas pressure is not highFuel gas pressure is not high4.4. Fuel gas pressure is not highFuel gas pressure is not high5.5. Instrument air pressure is not lowInstrument air pressure is not low6.6. Scanner air pressure is not lowScanner air pressure is not low6.6. Scanner air pressure is not lowScanner air pressure is not low7.7. Pilot gas pressure is not lowPilot gas pressure is not low8.8. Combustion air pressure is not lowCombustion air pressure is not lowpp9.9. ID fan is running ( Where applicable )ID fan is running ( Where applicable )

10.10. Steam drum level not low lowSteam drum level not low low

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BURNER MANAGEMENT SYSTEM BURNER MANAGEMENT SYSTEM -- CONTINUEDCONTINUEDSOME OF THE TRIP INTERLOCKS HANDLED BY BMS ARE :SOME OF THE TRIP INTERLOCKS HANDLED BY BMS ARE :SOME OF THE TRIP INTERLOCKS HANDLED BY BMS ARE :SOME OF THE TRIP INTERLOCKS HANDLED BY BMS ARE :During the burner startDuring the burner start--up , startup , start--up will be aborted when any of the up will be aborted when any of the following occursfollowing occurs

11 Pilot flame is not provedPilot flame is not proved1.1. Pilot flame is not proved,Pilot flame is not proved,2.2. Main flame is not provedMain flame is not proved

During operation the burner system will trip on any of the following During operation the burner system will trip on any of the following occurrenceoccurrence

1.1. Flame is not sensedFlame is not sensed2.2. Failure of instrument air pressureFailure of instrument air pressure3.3. Failure of scanner air pressureFailure of scanner air pressure4.4. Drum level low lowDrum level low low55 ID fan failureID fan failure5.5. ID fan failureID fan failure6.6. FD fan failureFD fan failure7.7. Fuel gas pressure lowFuel gas pressure low88 Oil lOil l

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8.8. Oil pressure lowOil pressure low

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PLCPLCPROGRAMMABLE LOGIC CONTROLLER :PROGRAMMABLE LOGIC CONTROLLER :

•• USED MORE FOR INTERLOCKS EVEN USED MORE FOR INTERLOCKS EVEN THOUGH CAN BE USED FOR CLOSED THOUGH CAN BE USED FOR CLOSED LOOP CONTROLS ALSOLOOP CONTROLS ALSO

•• FASTER AND HENCE MORE SUITABLE FASTER AND HENCE MORE SUITABLE FOR INTERLOCKSFOR INTERLOCKSFOR INTERLOCKSFOR INTERLOCKS

•• USED FOR CLOSED LOOP CONTROLS USED FOR CLOSED LOOP CONTROLS ALSO IF THE NUMBER OFALSO IF THE NUMBER OFALSO IF THE NUMBER OF ALSO IF THE NUMBER OF CONTROLLERS ARE LESS.CONTROLLERS ARE LESS.

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DCSDCSDISTRIBUTED CONTROL SYSTEMDISTRIBUTED CONTROL SYSTEM

•• AS THE NAME ITSELF IMPLIES , THIS IS AS THE NAME ITSELF IMPLIES , THIS IS ,,USED WHEN WHEN MANY USED WHEN WHEN MANY INDEPENDENT PROCESSES IN A PLANT INDEPENDENT PROCESSES IN A PLANT ARE TO BE CONTROLLED FROM ONE ARE TO BE CONTROLLED FROM ONE LOCATIONLOCATION

O S GO S G•• MORE SUITABLE WHEN LARGE MORE SUITABLE WHEN LARGE NUMBER OF CLOSED LOOP CONTROLS NUMBER OF CLOSED LOOP CONTROLS ARE INVOLVEDARE INVOLVEDARE INVOLVEDARE INVOLVED

•• SLIGHTLY SLOWER THAN PLCSLIGHTLY SLOWER THAN PLC

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Documents

BOILER CONTROLS &BOILER CONTROLS & … Control and instruments... · Boiler will trip if instrument air pressure fails. BURNER MANAGEMENT SYSTEM NATIONAL FIRE PROTECTION ACT ( NFPA)NATIONAL