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FLAME SCANNERSFLAME SCANNERS

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INTRODUCTION

PRINCIPLE PURPOSE OF FLAME SAFEGUARDSUPERVISIORY SYSTEM IS TO ENSURE THAT ITIS SAFE TO LIGHT THE BOILER AND CONTINUEBOILER OPERATION.

IT IS ALSO USED FOR BOILER SHUTDOWN. ACCURATE DETECTION OF A FIRE IS ONE OF

THE MOST IMPORTANT TASKS OF FSSS.

FOR THIS PURPOSE THERMOCOUPLES , FLAME

RODS OR FLAME SCANNERS ARE INSTALLED. UV, IR AND MULTIPLE FREQUENCY SENSING

ARE THE DIFFERENT TYPES OF FLAMESCANNERS.

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MECHANICAL COMPONENTSMECHANICAL COMPONENTS

Comprises of a stationary part called theflame scanner guide assembly and a removablepart called the flame scanner assembly.

FLAME SCANER GUIDE ASSEMBLY:- SCANNER HEAD HOUSING

FLEXIBLE METAL HOSE :- Adapts scanner to tilting ofwind box nozzles.

RIGID GUIDE PIPE SECTION:- Fixed to the wind boxand serves as a protective cover/packing gland.

COOLING AIR MANIFOLD:- is screwed onto theguide pipe

COVER PLATE: closes the wind box opening when

scanner is removed for maintenance.

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MECHANICAL COMPONENTSMECHANICAL COMPONENTS

FLAME SCANNER ASSEMBLY:-

SCANNER HEAD ASSEMBLY:- Comprises of ascanner head body with the collimator tube, shield,

collimating lens, barrel, mounting plate,compression spring, one end of fiber optic cableand a plug.

FLEXIBLE METAL HOSE:- Houses the fiber opticcable

RIGID PIPE:- Houses the fiber optic cable SCANNER HOUSING ASSEMBLY:- houses the

scanner head electronics card which convertsvisible light signal to equivalent electrical signal.

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FLAME SCANNER ASSEMBLY:-

FLEXIBLE

METAL

HOSERIGID PIPE

SCANNER

HOUSING

SCANNER HEAD

ASSEMBLY

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FLAME SCANNER ASSEMBLY:-

COMPRESSION SPRING FIBER OPTIC CABLE

PLUG

SCANNER HEAD BODYLENSSPACER

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ELECTRICAL COMPONENETSELECTRICAL COMPONENETS

LOCAL:- SCANNER HOUSING ELECTRONICS

REMOTE :- POWER SUPPLY MODULE:-

INTENSITY & FAULT DETECTION CARD:-

FREQUENCY DETECTION CARD:-

LAMP & METER CARD:-

LAMP DRIVER CARD:-

2/4 FLAME INDICATION & FAULT ALARM:-

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ELECTRICAL COMPONENTSELECTRICAL COMPONENTS

SCANNER HOUSING ELECTRONICSSCANNER HOUSING ELECTRONICS :- Flame signal (light) transmitted via the fiber

optic cable strikes a photodiode.

Light signal is converted into an small current

signal by the photodiode. Current signal is converted to a voltage signal.

(1.5v for intense brightness and 6.4 v for nolight)

Voltage signal is amplified by an amplifier ofgain 1/3.

Voltage signal is the converted into a currentsignal and sent to remote electronics.

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SCANNER HOUSING ELECTRONICSSCANNER HOUSING ELECTRONICS

PHOTOCOUPLER

ASSEMBLY

TRIMMING POTS

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ELECTRICAL COMPONENTSELECTRICAL COMPONENTS

POWER SUPPLY CARD :-

I/P voltage and frequency:- 110V 50 Hz

O/P voltage:- +15v, -15VDC

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POWER SUPPLY CARDPOWER SUPPLY CARD:-

P/S SWITCH

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ELECTRICAL COMPONENTSELECTRICAL COMPONENTS

INTENSITY AND FAULT DETECTION CARDINTENSITY AND FAULT DETECTION CARD :-

- Current Signal Converted To Equivalent millivoltsignal.

- Intensity slope is inverted and multiplied by factor

3.

- This active flame signal consists of intensity andfrequency components. The active flame signal istransmitted to the frequency detection cards aswell as the intensity circuitry.

- The ac component is eliminated to obtain anintensity only flame signal.

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INTENSITY AND FAULT DETECTION CARDINTENSITY AND FAULT DETECTION CARD

INTENSITY

INDICATOR

DROP OUT

SWITCH

DROP OUT

POT

PULL IN POT

PULL OUT

SWITCH

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ELECTRICAL COMPONENTSELECTRICAL COMPONENTS

FREQUENCY DETECTION CARDFREQUENCY DETECTION CARD :-

- Two types of frequency detection cards used. Oneis tuned to frequency 3hz to determine existencefireball flame frequency in the active flame signal

and the other is tuned to 29hz and is used fordetermining oil gun flame frequency.

- Active flame signal from intensity and faultdetection card is ac coupled to block intensityinformation.

- Ac signal is compared with set frequency. A matchgenerates a logic one.

- Delay of 2 secs is provided during frequencypermissive drop out.

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FREQUENCY DETECTION CARDFREQUENCY DETECTION CARD

FILTER

SWITCH FREQUENCY LED

YELLOW TRIM

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ELECTRICAL COMPONENTSELECTRICAL COMPONENTS

LAMP AND METER CARDLAMP AND METER CARD :-

- Oil guns flame/no flame and visual intensityFAULT warnings are generated.

- Flame intensity signal is indicated on Flameintensity mA Meter.

- Power supply of +/-15Vdc is provided to thescanner housing electronics.

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LAMP AND METER CARDLAMP AND METER CARD

FAULT LED

INTENSITY METER

FLAME LED

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ELECTRICAL COMPONENTSELECTRICAL COMPONENTS

2/4 FAULT INDICATION AND FAULT2/4 FAULT INDICATION AND FAULTALARMALARM:-

- Provides contact closure of relay when at least

2 out of 4 scanners are detecting fireballflame.

- Provides contact closure of relay when fault isdetected on any scanner cable or scannerhead electronics.

- These contact are further used in DCS:

- Fault signal is used to alert operator ofexisting fault is system.

- 2/4 flame scanner in service is used in Boiler

tripping logic.

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2/4 FAULT INDICATION AND FAULT ALARM2/4 FAULT INDICATION AND FAULT ALARM:-

RELAYS

2/4 FLAME

FAULT

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