FLame Sscanner

1. Presented By
“BHELSCAN”
FLAME SCANNER

2. INTRODUCTION
•PRINCIPLE PURPOSE OF FLAME SAFEGUARD SUPERVISIORY
SYSTEM IS TO ENSURE THAT IT IS SAFE TO LIGHT THE
BOILER AND CONTINUE BOILER OPERATION.
•IT IS ALSO USED FOR BOILER SHUTDOWN.
•ACCURATE DETECTION OF A FIRE IS ONE OF THE MOST
IMPORTANT TASKS OF FSSS.
•UV, IR AND VISIBLE LIGHT ARE THE DIFFERENT TYPES OF
FLAME SCANNERS.
UV Type : 10 nm to 400 nm
Visible light Type : 380 nm to 740 nm
IR Type: 700 nm to 1 mm
“BHELSCAN” uses visible spectrum for flame sensing.

3. •AN IDEAL FLAME SCANNER DETECTS A FLAME OF
INTEREST WHILE TOTALLY IGNORING OTHERS AND IS
UNAFFECTED BY CHANGES IN AMBIENT CONDITIONS.
•A FLAME SCANNER IS A SENSOR THAT DETECTS
PRESENCE OF FIRE IN THE BOILER BY ABSORBING THE
LIGHT ENERGY EMMITTED BY THE FIRE.

4. The microcontroller based flame sensing system is designed primarily for use on
coal fireball and stable oil flame.
It senses the visible light given off by the flame and can recognize a coal/oil
flame by its characteristic fluctuations.
The system consists of a fibre-optic connected scanner head assembly and a
chassis containing electronic signal processing modules. The scanner head assy. is
located at the boiler and the chassis with electronics is mounted in the control
room. The chassis may be located up to 200 metre from the boiler.
The scanner head assy. is normally installed in the wind box assembly

7. Scanner head
LOG. AMP.
PHOTO
DIODES
LED
FEEDBACK
VOLTAGE
TO
CURRENT
CONVERTER
E
FIBER OPTIC
CABLE
4 wire shielded cable to rack

8. SPECIFICATION
Input signal : 0 to 2mAAC from Head Electronics
Signal : 4 Microcontroller Processor Modules for 1 elevation
2/4 Processor : 2/4 logic detection & fault alarm
Programmable : Pull in, Pull out, Parameters Flicker frequency for oil,
Flicker frequency for coal
Display : 2 ½ digit LED display
Display mode : By Push button selection
Parameter : 4 x 8 bit DIP switch setting
Communication : Serial interface
Enclosure : 19” Rack with 3U size cards

9. MECHANICAL COMPONENTS
 Stationary part -- “flame scanner guide pipe assembly”
 removable part--“flame scanner assembly”.
Flame Scanner Guide Pipe Assembly:-
◦ SCANNER HEAD HOUSING
◦ FLEXIBLE METAL HOSE :- Adapts scanner to tilting of
wind box nozzles.
◦ RIGID GUIDE PIPE SECTION:- Fixed to the wind box
and serves as a protective cover/packing gland.
◦ COOLING AIR MANIFOLD:- is screwed onto the guide
pipe
◦ COVER PLATE: closes the wind box opening when
scanner is removed for maintenance.

10. Flame Scanner Assembly:
•SCANNER HEAD ASSEMBLY:- Comprises of a scanner
head body with the collimator tube, shield, collimating lens,
barrel, mounting plate, compression spring, one end of fiber
optic cable and a plug.
•FLEXIBLE METAL HOSE:- Houses the fiber optic cable
•RIGID PIPE:- Houses the fiber optic cable
•SCANNER HOUSING ASSEMBLY:- houses the scanner head
electronics card which converts visible light signal to
equivalent electrical signal.

11. FLAME SCANNER ASSEMBLY:-
FLEXIBLE
METAL
HOSE RIGID
PIPE
SCANNER
HOUSING
SCANNER HEAD
ASSEMBLY

12. FLAME SCANNER ASSEMBLY:-
COMPRESSION
SPRING
FIBER OPTIC
CABLE
PLUG
SCANNER HEAD
BODY
LENS
SPACER

13. COOLING AIR REQUIREMENTS:-
Cooling air passes through the guide pipe, the flexible hose and
between the scanner head and housing. The air is discharged into the
furnace by removing any heat picked up from the hot combustion air.
The scanner head should not be exposed to a continuous temperature
above 300°F without cooling air.
Cooling air flow requirements are (per scanner) 55 cfm at 120°F
(Max.).
Air manifold pressure at the scanner guide pipe must be 150mmwc
above furnace pressure.
After shutting down the unit, scanner cooling air must be maintained
until furnace conditions are such that the scanner assembly cannot
overheat.

14. ELECTRICAL COMPONENTS:-
 The electrical components of the BHELSCAN system are contained in the
scanner housing assemblies and the card rack assembly.
 A photo diode located in each scanner housing assembly converts visible
light (flame signal) observed by the scanner head into an electrical
equivalent signal.
 The scanner housing output signal is an AC current signal, which is sent to
the card rack assembly for processing.
 In the card rack assembly, each current flame signal is converted into a
voltage flame signal. The voltage flame signal is then separated into
intensity and frequency components.
 An intensity signal indicates the magnitude of the flame brightness on 2½
digit LED display(Range is 0-100%).
 A fault signal is established if the intensity component is less than its
minimum preset limit or greater than its maximum preset limit. If a fault
signal is established, a fault LED is lit and flame signal cannot be
established for that corner. Hence oil flame or coal flame lights will not
come ON.

15. DESCRIPTION OF MODULES:-
Flame scanner card rack assembly consists of the following modules:
1. Flame processor module- 4 Nos.
2. 2/4 output module - 1 No.
3. Power supply unit - 1 No.
There are two semiconductor fuses rated for 63mA are available in the
flame processor motherboard to protect the DC supply to scanner head
electronics.
DO NOT REMOVE ANY MODULE WITH POWER ON
The front facia of this module consists of a 7-segment display, 9 status LEDs and
one Push Button

16. Figure - 6B
BHELSCAN – GENERAL ARRANGEMENT

19. Figure - 7B
BHELSCAN –FLAME PROCESSOR MODULE
Intensity
pull in
Intensity
pull out
Coal freq.
Set value
Oil freq.
Set value
AC gain
pot.(Oil)
AC gain
pot.(Coal)

20. 2/4 Module
 This receives digital signals corresponding to “Flame 1 ON”
from all 4 flame processor module.
 If two or more than two “Flame 1” inputs are available, 2/4
Module signals presence of fireball.
 However , for fireball indication in DCS , corresponding feeder
“ON” bit is taken in an AND Gate along with the above
mentioned 2/4 Logic.

21. Figure - 8B
BHELSCAN –2/4 MODULE
2/4 Relay
Fault Relay

22. Figure - 9B
BHELSCAN –POWER SUPPLY MODULE (FRONT VIEW)
Figure - 9C
BHELSCAN –POWER SUPPLY MODULE (REAR VIEW)

23. Power Supply Module
 This will work in 110V AC or 230V AC as given in the nameplate
1. +15 V DC
2. –15V DC
3. +5.0V DC
 All the above DC outputs are over voltage and short circuit protected.
There is a fuse available in the power supply motherboard, whose
rating is 2 Amps

24. ◦ System Operation Test (FAULT)
1. Disconnect the signal wire - intensity display by flashing 100%.
2. During furnace OFF- display ‘00’ to indicate the dark furnace
condition.
3. If any power supply wire is cut or any short circuit in the signal wire
to ground- display will show ‘00’ flickering.
4. When Power supply +15Vdc fuse blown - flashing 100%.
5. When Power Supply -15Vdc fuse blown –Any Value

25. There are 4 DIP switches (8 bits) are available to set the following data
in binary form to the microcontroller.
The digital outputs of flame1 (coal) and flame2 (oil) status are fed to
the 2/4 output module. A 4-20 mA current output is available to
represents the intensity of the flame.
S.NO
.
TYPICAL
VALUE
PRESENT
VALUE
1. Pull in value (PI) 40% 40%
2. Pull out value (PO) 30% 20%
3. Coal frequency set value
(F1)
5Hz 3Hz
4. Oil frequency set value
(F2)
30Hz 25Hz

26. Dip Switch Setting Procedure
Locate S1 DIP switch - Set ‘40’
DIP switch position: 8 7 6 5 4 3 2 1
Setting status: OFF OFF ON OFF ON OFF OFF OFF

27. Calibration of Scanner Head Electronics:-
Gain and Offset Adjustment:
The following equipment will be required :
a. Digital voltmeter (DVM)
b. 1 mA dc current source (1 V dc in series with a resistor; 1k)
c. 1 μA dc current source (1V dc in series with a resistor; 1M)
d. Small soldering pencil

28. Disconnect the positive lead of the photodiode.
Simulate a photodiode input by connecting the 1 mA dc current
source to the photodiode terminals.
Connect the digital volt meter between signal “C” and common “D”
terminals on the electronics card.
Turn the scanner power supply “on” and adjust potentiometer R101 to
provide a reading of 0.000 V.
Replace the 1 mA dc current source with a 1 μA source.
Adjust potentiometer R103 to provide a reading of 1.000 V

29. Dark Furnace Bias Adjustment :
Completely block all light.
Connect a digital voltmeter between the signal C and common D
terminals on the electronics card.
The power supply switch should be turned on.
Adjust potentiometer R113 so that the DVM reads approximately
2.1V.

32. Maintenance And Trouble Shooting
Scanner Head :
•The scanner head should be inspected periodically and cleaned, if
necessary.
Fibre optic cable:
•The collimator shield and the lens on the end of the fibre-optic
cable should also be inspected periodically for cleanliness.
Electrical components:
•The electronic modules do not require periodic maintenance.
•If AC power is not ON.
•If DC supplies are not ON.
•In flame processor module, fault lamp should be OFF.
•In 2/4 flame module, the fault lamp should be OFF.
•Do not insert or pull out any module from the connector when
power is ON.

33. THANK YOU….