flame scanners

BHARAT HEAVY ELELCTRICALS

LIMITED HIGH PRESSURE BOILER PLANT

TIRUCHIRAPPALLI-620 014.

Operation & Maintenance Manual of

BHELSCAN FLAME SCANNER SYSTEM (BN10)

Project: NEW PARLI TPS

Cust. No.:0361 BHARAT HEAVY ELELCTRICALS LIMITED, HIGH PRESSURE BOILER PLANT Controls And Instrumentation / Fossil Boilers), Tiruchirapalli - 620 014, INDIA Phone: 91 (0431) 257 5218 , 257 5027

Page 1 of 26

BHELSCAN O & M MANUAL NEW PARLI TPS

TABLE OF CONTENTS : 1. Introduction

2. System specification

3. Mechanical components

4. Cooling air requirements

5. Electrical components

6. Description of modules

6.1 Flame processor module

6.2 2/4 output module

6.3 Power supply module

6.4 Scanner head electronics

7. Communication interface

8. Installation and start up procedures

8.1 Mechanical components

8.2 Cooling air

8.3 Electrical components

8.4 System operation test

8.5 DIP switch setting procedures

8.6 Calibration of scanner head electronics

9. Maintenance & troubleshooting

9.1 Scanner head

9.2 Fibre Optic cable

9.3 Electrical components

10. List of Figures

Figure-1 : Windbox arrangement showing Flame scanner system

Figure-2 : Flame Scanner Guide pipe assembly

Figure-3 : Flame scanner assembly with optical head

Figure-4 : Collimeter lens with barrel assembly

Figure-5 : Functional block diagram

Figure-6A : BHELSCAN - General arrangement

Page 2 of 26 BHELSCAN O&M MANUAL

Figure-6B : BHELSCAN - General arrangement


Figure-6C : Schematic of processor motherboard

Figure-7A : Block diagram of Flame processor

Figure-7B : BHELSCAN Flame processor module

Figure-8A : Block diagram of 2/4 output module

Figure-8B : BHELSCAN 2/4 module

Figure-9A : Block diagram of power supply

Figure-9B : BHELSCAN Power supply module (Front view)

Figure-9C : BHELSCAN Power supply module (Rear view)

Figure-9D : Schematic of power supply motherboard

Figure-10 : Block diagram of Scanner Head electronic module

Figure-11A : Flame scanner interconnection diagram

Figure-11B : TB wiring details (Front mounted TB version)

Figure-11C : TB wiring details (Rear mounted TB version)

Figure-11D : BHELSCAN TB arrangement (Rear mounting)



1. INTRODUCTION :

The microcontroller based flame sensing system is designed primarily for use on

coal fireball and stable oil flame ignited by high energy arc (HEA) ignitor. 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. A shielded four-conductor

cable sends power to the scanner head electronics and returns an electronic signal

representing flame to the chassis.

The scanner head assy. is normally installed in the wind box assembly (Figure-

1). Refer to the respective project wind box arrangement drawing to determine the

location of scanner head assy. in the system.

The prime output of flame sensing system is called the two out of four flame ON

for coal, when two or more than two coal flame in an elevation is detected and individual

flame ON for oil. The output is represented by the positioning of a set of form C

contacts (break before make). A current signal is also available to indicate the individual

flame intensity corresponding to each corner. RS232C serial output is available for

computer/DCS connectivity.

2. SYSTEM SPECIFICATION :

Specifications Power supply : 110/230V AC, 50/60 Hz (Refer name plate)

Input signal : 0 to 2mA AC from Head Electronics


Signal Processor : 4 Microcontroller Modules for 1 elevation


2/4 Processor : 1 Microcontroller Module 2/4 logic detection &

fault alarm

Programmable Parameters : Pull in, Pull out, Flicker frequency for oil, Flicker

frequency for coal

Display : 2 digit LED display

Display mode selection : By Push button

Parameter setting : 4 x 8 bit DIP switch

Communication : Serial interface

Enclosure : 19 Rack with 3U size cards

BHELSCAN comes in two versions - one with terminal blocks for field interconnection

fitted in the front; another with terminal blocks fitted in the back side. Version with TB

fitted in the front is recommended for panels in which BHELSCAN rack assemblies fitted

has only front doors and no back doors provision. Version with TB fitted in back is

recommended for panels having back doors also. All other components are same for

both versions.

3. MECHANICAL COMPONENTS :

The complete mechanical assembly is comprised of a stationary part, called the

flame scanner guide pipe assembly and a removable part, called the flame scanner

assembly.

3.1 Flame Scanner Guide Pipe Assembly

The flame scanner guide pipe assembly consists of a scanner head housing, a

flexible metal hose, a rigid guide pipe section, a cooling air manifold and a cover

plate.(Figure 2)


Guides inside the housing center the scanner head and provide a uniform

passage for the external cooling air. The end ring in the housing forms a mechanical

stop for the scanner head. The flexible hose assembly and the flexible guide pipe


adapt the scanner to the tilting of the wind box nozzle and angle mounting. The flexible

hose is brazed to the guide pipe and scanner head housing.

CAUTION

WHEN SCANNER ASSEMBLIES ARE SHOP-INSTALLED, THEY ARE

MOUNTED WITH THE FLEXIBLE HOSE COMPRESSED TO ITS

MINIMUM LENGTH WHEN THE WIND BOX IS AT ZERO

(HORIZONTAL) TILT. IF A SCANNER GUIDE PIPE IS FIELD-

INSTALLED, BE SURE IT IS MOUNTED IN THE SAME MANNER TO

PREVENT DAMAGE TO THE FLEXIBLE HOSE AND CONNECTIONS

WHEN THE NOZZLE IS TILTED THROUGH ITS RANGE. ANY RADIUS

OF CURVATURE GREATER THAN 18-IN MAY BE UTILIZED AS LONG

AS ITS CROSS SECTION IS CIRCULAR AND DOES NOT RESTRICT

FREE MOVEMENT OF THE SCANNER HEAD WITHIN THE CURVED

PORTION.

The guide pipe is normally fixed in the wind box front by means of a packing

gland. The cooling air manifold is screwed (NPT) onto the guide pipe. The cooling air

manifold is drilled and tapped to accept a flexible hose connection at its cooling air inlet

and has an opening for the flame scanner head assembly. The scanner opening must

be closed with the cover plate when the assembly is removed for maintenance.

3.2 Flame Scanner Assembly The flame scanner assembly has four sections similar to those found on the

flame scanner guide pipe. There is a flame scanner head assembly, flexible metal hose,

rigid pipe and the scanner housing assembly.

The flame scanner head assembly (Figure - 3 ) consists of the scanner head

body, which contains the collimator tube and shield, the collimating lens and barrel, a

mounting plate, a compression spring, one end of the fibre-optic and a plug.



The fibre optic cable is installed in the flexible metal hose and rigid pipe sections.

It transfers the visible light flame signal from the lens to the photodiode mounted in the

scanner housing assembly.

When the scanner assembly is inserted in the guide pipe, cooling air from the

cooling air manifold enters the scanner housing through two holes. This air flows down

the rigid pipe and flex metal hose to cool the fibre-optic cable. Air is discharged into the

furnace through the scanner head body and collimator tube. No seal gaskets are

required in the scanner head assembly because of the pressure differential between the

cooling air inside the scanner and the furnace. There should be no reason to

disassemble the scanner head assembly, except to clean the collimator shield (see the

Maintenance and Trouble shooting section of this manual).

The scanner housing couples the flame scanner assembly to the guide pipe and

contains the electronics for conditioning the fibre-optic-transmitted signal.

A weatherproof disconnect coupling is provided to conveniently connect external

wiring. A hexagon adapter adapts the connector to a in. pipe thread. Sealtite flexible

hose or a similar weatherproof conduit should be used between the disconnect coupling

and the rigid conduit leading from the wind box assembly.

The flame scanner head assembly can be assembled in the following manner :

1. Slip fit the collimator tube and shield assembly into the scanner head body and

hold it in place with a single Allen head screw. Using spacers, position the shield

on the collimator to a allow cooling air to flow through the head assembly. (

Figure 4)

NOTE


A wind box structure will sometimes restrict the location of the guide pipe

scanner head housing. To permit the scanner to see the flame, a prism

may be installed in place of the collimator shield. Use care when placing


the scanner in the guide pipe to assure proper orientation of the scanner

head assembly.

2. Thread the fibre-optic cable, which is normally coiled inside the scanner housing

assembly, through the rigid pipe, flex metal hose and the scanner head body

plug. Make sure the jam nut is in place on the cable before installing the

compression spring and mounting plate. Then screw the collimating lens barrel

onto the cable.

3. Lock the mounting plate to the lens barrel with the jam nut.

4. Insert the lens barrel in the scanner head body until the mounting plate rests

against the stop pins.

5. Insert the compression spring and plug. Three socket head screws hold the plug

in the scanner head body.

4. COOLING AIR REQUIREMENTS : The external cooling air passes through the guide pipe, the flexible hose and the annulus

between the scanner head and housing. The air is discharged into the furnace at the top

of the scanner head, thereby removing any heat picked up by the scanner from the hot

combustion air. The scanner head should not be exposed to a continuous temperature

above 300F without cooling air.

NOTE


When the scanner assembly housing adapter flange is disconnected, the scanner assembly must be removed from the guide pipe immediately.

Wrap a cloth around the scanner support pipe and hold it firmly against the

cooling air manifold to minimize the escape of cooling air while the head is

being removed. The head should then be held in the rag to protect it from

damage. Install the cover plate to retain the cooling air flow within the


scanner guide pipe. This prevents a reduction of cooling air pressure at

the remaining scanners.

Cooling air flow requirements are (per scanner) 55 cfm at 120F (maximum

temperature measured at the scanner air booster fan inlet). Air manifold pressure at the

scanner guide pipe must be 150mmwc.(g). above furnace pressure for all operating

conditions. After shutting down the unit, scanner cooling air must be maintained until

furnace conditions are such that the scanner assembly cannot overheat. Shut off valves

must not be installed in cooling air lines to the scanners.

5. 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 electrical signal is conditioned by

amplifiers located in the scanner housing assembly. The scanner housing output

signal is an AC current signal, which is sent to the card rack assembly for processing.

Refer functional block diagram. ( Figure 5 )

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. The intensity component of the signal varies between no flame value (dark

furnace) and a normal flame value based on the actual flame intensity. The frequency

component of the signal is used to prove that an active flame exists.

(a) An intensity signal indicates the magnitude of the flame brightness. A 2

digit LED display in the front facia of flame scanner module displays intensity

in percentage. Range is 0-100%.


(b) 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.


(c) When the value of intensity component exceeds the field adjusted limits (pull

in, pull out settings), an intensity light will come ON at the associated scanner

channel. A flame signal will be established only if no fault (fault LED is OFF)

signal exists and a predetermined frequency component (frequency F1, F2

setting) is proven to exist.

The frequency of the fire ball (coal flame) is normally lower than the frequency of the

individual oil gun flame. Therefore, when at least 2 out of 4 scanner channels show coal

flame, the system 2/4 flame light will come ON in the front facial of 2/4 module. If any

scanner channel indicates a fault, the associated scanner channel fault LED will come

along with the system fault LED and that channels flame output will be disabled. The 2/4

module gives 2 changeover contacts for 2/4 flame and one changeover contact output

for system fault. Description of the various modules are given in the following sections:

6. DESCRIPTION OF MODULES:

The 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.

Refer BHELSCAN general arrangement drawing. ( Figure 6A & 6B )

The flame processor modules and 2/4 output module are mounted in processor

motherboard, assembled in the card rack. Refer Schematic diagram of Processor

mother board.( Figure 6C ) The power supply unit is mounted in the power supply

motherboard, assembled in the card rack.

6.1 Flame Processor Module : (Refer block diagram Figure - 7A & 7B) :


This module is a standard euro card suitable for 19 rack assembly. Flame

processor module is located in the slots 1 to 4 in the processor module. These modules

can be interchanged within them. The set values can be verified before putting into its

slots. The scanner head current signal (0 2.0 mA) enters flame processor module and

is converted to voltage. The voltage is signal is normalized in signal conditioner such


that, a high voltage represents the bright furnace and low voltage represents the dark

furnace.

This signal is divided into three parts. One signal goes to intensity monitoring

circuit. This consists of a voltage amplifier and an ADC. The output of this ADC is

connected to Microcontroller.

The second and third signals are fed to frequency detection circuit. This circuit

consists of an AC amplifier and a wave shaper. One output represents the coal flame

fluctuation and the other output represents the oil flame fluctuation. The outputs are fed

to microcontroller. The AC gain can be adjusted to suit the furnace flame condition

independently for coal and oil flame flicker levels by RP1 and RP6 single turn

potentiometers respectively.

The +/-15 V DC and GND are extended to scanner head electronics located at

furnace front in the field from this module. There are two semiconductor fuses rated for

63mA are available in the flame processor motherboard to protect the DC supply to

scanner head electronics. The removal of this module blocks the DC supply to field.

DO NOT REMOVE ANY MODULE WITH POWER ON

There are 4 DIP switches (each switch with 8 bits) are available to set the

following data in binary form to the microcontroller. For DIP switch settings, refer DIP

SWITCH SETTING PROCEDURE.

a. Pull in value (typical value is 40%)

b. Pull out value (typical value is 30%)

c. Coal frequency set value (typical value is 5 Hz.)

d. Oil frequency set value (typical value is 30 Hz.)

The front facia of this module consists of a 7-segment display, 9 status LEDs and

one Push Button. Card pullers are available to remove the card from the rack. A mode

PB can change the display mode to scroll the various values.



The heart of the system is an 8-bit microcontroller. This receives the signals from

ADC, wave shaping circuit, mode PB and DIPswitches. From these signals, the

microcontroller decides the flame status and energies the relay. Also, the status of

flame1 and flame 2 and fault are transferred to the 2/4 output module. The

microcontroller updates the display and LED status according to the input.

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. This circuit consists of a DAC and current converter.

Relay outputs are available in form of change over contact for flame 2(oil) output

to use in BMS of boiler. For the location of DIP switches and AC gain potentiometers,

refer Figure - 7B.

6.2 2/4 Output Module : (Refer block diagram Figure 8A & 8B ) :

This card is a standard euro card suitable for 19 rack assembly. This is located

in the 5th slot of processor motherboard. The heart of the module is an 8-bit

microcontroller. This receives digital signals corresponding to flame1 ON from all four

flame processor modules. Whenever, two or more than two flame 1 (coal) inputs are

available, this module gives output for 2/4 flame ON output. This indicates the presence

of fireball. There are two relays available. One relay is for the 2/4 output of coal flame.

The other relay is for fault alarm to DCS. RS232C serial communication circuit, transfer

the flame parameters for all processor modules to computer on-line via serial port. Two

sets of 2/4 output relay contacts are available at the terminal. These are changeover

contacts. In the front facia, two status LEDs are available for 2/4 output indication and

fault status. Refer Figure 8B for the location of 2/4 relay (Fireball flame ) and fault

relay.

6.3 Power Supply Module : (Refer Figures - 9A, 9B, 9C & 9D ) :


This is a linear power supply suitable for 19 rack assembly. This is mounted in

power supply motherboard. This will work in 110V AC or 230V AC as given in the

nameplate. This is factory set. There are three DC outputs produced in this module.


1. +15 V DC @ 0.75 Amps maximum

2. 15V DC @ 0.25 Amps maximum

3. +5.0V DC @ 1.5 Amps maximum

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. A DPDT

toggle switch is provided in the power supply motherboard to switch ON the AC

power supply to this module. In the front facia, four status LEDs are available for

presence of AC power ON, -15V DC ON, +15V DC ON and +5 V DC ON. All four

LEDs should glow for the normal operation of flame scanner.

6.4 Scanner Head Electronics : (Refer figure 10 ) :

This is a circular module available inside the flame scanner head assembly. This

is mounted at furnace front in the windbox. A special triple shielded flame scanner cable

connects this module to respective flame processor module in the flame scanner card

assembly at flame scanner panel located at remote control room.

This module converts the light transmitted from the furnace flame. (via a fibre

optic cable) to an electrical signal. Visible light from the flame strikes photo diode and is

converted into a current signal. This current is linear function of illumination (intensity)

and covers five-decade range of lux. Photo diode signal is converted to log signal

voltage in the temperature log amplifier to cover the entire range of intensity. Amplifier

offset and gain adjustments are factory set through potentiometers R101, R103. This

voltage signal is converted to current signal (0 2.0 mA) for transmission to flame

processor module.

A feedback LED is mounted in the photo diode holder, to avoid the saturation of

log amplifier in the event of very low light or dark furnace conditions. This feedback loop

is the key circuit in the electronic fault detection scheme. The light emitted by the

feedback LED is adjusted by R114 potentiometer during calibration at laboratory /

factory.



7. COMMUNICATION INTERFACE :

Serial communication (RS232C) output is provided in each BHELSCAN covering

four corners of one elevation. Terminal block (TB5) in system mother board has 3

terminals viz. 10, 11, 12 for Transmit (Tx), Receive (Rx) and ground. Prepare a cable (2

pair twisted 0.5 Sq.mm shielded cable) with one side soldered to 9 pin D type connector

suitable for inserting into COM1 or COM2 serial port of personal computer and connect

the other side to these terminals. The 2/4 output module periodically interrupts each

flame scanner and collect the following data. This data will be communicated via serial

output approximately once in a second.

a. Intensity set value

b. Pull in set value

c. Pull out set value

d. Frequency 1 (coal) set value

e. Frequency 2 (oil) set value

f. Actual frequency of flame 1 (coal)

g. Actual frequency of flame 2 (oil)

h. Fault status

i. Flame 1 status

Load and run the PC2Scanner.exe programme supplied with the system. This

program will display the following :

Baud Rate = 9600

Stop Bit = 1

Parity = No parity

To select COM1 or COM2 (Enter 1 or 2) =

Now enter the COM port Number 1 or 2 in which the communication cable is

connected. Communication will be established and PC will display the following

corresponding to 4 corners.



FLAME SCANNER

CORNER1 CORNER2 CORNER3 CORNER4

Actual Intensity

Pull in set

Pull out set

Frequency 1 set

Frequency 2 set

Actual frequency 1

Actual frequency 2

Flame 1

Flame 2

The above table will be updated automatically every second approximately.

8. INSTALLATION AND START-UP PROCEDURES :

8.1 Mechanical Components :

Make sure the Safe Scan head assembly is properly inserted in the flame scanner guide

pipe assembly and that sufficient clearance exists directly behind each guide pipe to

allow easy removal.


A weatherproof quick-disconnect electrical coupling (Figure 3) is provided for the

external wiring. A hexagonal adapter provides for the connection of a -in. pipe thread

attachment. Sealtite flexible hose or a similar weatherproof conduit should be used

between the quick-disconnect coupling and the rigid conduit. The flexible hose should


be long enough (4 or 5 ft) to withdraw the scanner from the guide pipe without

disconnecting the coupling.

8.2 Cooling Air : CAUTION

THE SCANNER HEADS MUST BE COOLED WHENEVER THERE IS A FIRE IN

THE FURNACE OR THE BOILER INTERIOR IS ABOVE 300F. A COOLING

AIR SYSTEM MUST BE PROVIDED AND CHECKED OUT BEFORE THE

BOILER IS LIT OFF. On balanced draft units, the cooling air for the scanners is frequently supplied by a

separate fan and piped to the scanner cooling air manifolds. The scanner cooling air

supply is taken from the forced draft (FD) fan discharge duct in combination with

combustion air to the ignitors. In this case an emergency damper, a low air pressure

switch, a high air pressure switch and a scanner fan are also provided. The scanner fan

starts when the air pressure gets too low, usually at 6 in. w.g.

Most air systems are supplied with air filters between the scanner fan and the cooling air

manifold. A differential pressure gauges and switches to actuate an alarm are installed

across the filter to provide information on filter condition. Filters should be checked

periodically for cleanliness.

The emergency damper opens to admit ambient air to the system when the FD fans are

out of service.

All components should be checked for proper operation.

8.3 Electrical Components :


Input and output connections to the flame scanner card rack assembly are to be done as

per the Flame scanner interconnection diagram Figure 11A and as per the following


table: (Also refer for detailed TB wiring, Figure 11B for front mounted TB version &

Figures 11C & 11D for rear mounted TB version )

Power supply mother board

TB No. Terminal No.

DESCRIPTION

TBP1 1 Phase (230V or 110V as given in the name plate)

TBP1 2 Neutral

TBP1 3 Earth

Processor mother board


TB No. Terminal No.

DESCRIPTION MARKING

TB1 Corner 1 1 +15V to Head Electronics B+

TB1 Corner 1 2 -15V to Head Electronics B-

TB1 Corner 1 3 Signal from Head Electronics SIG

TB1 Corner 1 4 Signal ground from Head Electronics GND

TB1 Corner 1 5 Power supply shield & overall shield Sh.

TB1 Corner 1 6 Flame-2 relay contact - NO NO

TB1 Corner 1 7 Flame-2 relay contact common COM

TB1 Corner 1 8 Flame-2 relay contact NC NC

TB1 Corner 1 9 Current output negative I-

TB1 Corner 1 10 Current output positive I+

TB2 - Corner 2 1 +15V to Head Electronics B+










TB2 Corner 2 9 Current output positive I-

TB2 Corner 2 10 Current output negative I+

TB3- Corner 3 1 +15V to Head Electronics B+










TB4 - Corner 4 1 +15V to Head Electronics B+










TB5 1 2/4 flame contact NO NO1

TB5 2 2/4 flame contact common COM1

TB5 3 2/4 flame contact NC NC1

TB5 4 2/4 flame contact NO NO2

TB5 5 2/4 flame contact common COM2

TB5 6 2/4 flame contact NC NC2

TB5 7 System fault contact NO/NC jumper

selectable

NO/NC

TB5 8 System fault contact common COM

TB5 9 No connection


TB5 10 Transmit TX

TB5 11 Receive RX

TB5 12 Ground GND

8.4 System Operation Test : After installation is completed, the following tests can be done to verify proper operation

of the system:

1. At one channel, disconnect the signal wire from the terminal block. With the

power switch in ON position, the intensity display should show input open by

flashing 100%. The channel fault light should be ON and the system fault

light in 2/4 module should be ON.

2. Reconnect the signal wire to the terminal block. The corner fault light now

should be OFF. The system fault alarm light in 2/4 module should also go

OFF if none of the other corners indicate fault. The intensity display should

return to a normal indication.

3. Repeat step 1 & 2 for all channels.

4. During furnace OFF condition, the display corresponding to all corners shall

show 00 to indicate the dark furnace condition.

5. If any power supply wire is cut or any short circuit in the signal wire to ground,

then the display will show 00 flickering. The fault LED will glow. Switch OFF

the power supply and check the wire continuity. This condition shall be set

right, before proceeding further.

6. Whenever the power is switched ON, the display will show the intensity. The

corresponding IN LED will glow.

7. The display mode can be changed by momentarily pressing and releasing the

MODE PB (square PB).

8. The following display modes are available.

1. IN intensity

2. PI-Pull in set value of intensity

3. PO-Pull out set value of intensity

4. F1- coal frequency set value


5. F2-oil frequency set value


6. AF & F1- actual frequency of coal

7. AF & F2- actual frequency of oil

9. Select PI mode. The display should read the pull-in set value in %. Similarly,

change the modes and verify the other values as shown from 6.2 to 6.5

above.

10. Press mode PB again momentarily. Now, LEDs corresponding to AF and F1

both will glow simultaneously. The display reads the actual coal frequency

(F1).

11. Press mode PB again momentarily. Now, LEDs corresponding to AF and F2

both will glow simultaneously. The display reads the actual oil frequency (F2).

12. To change the set values of IN, PI, PO, F1 and F2 if needed, refer

parameter setting procedures given above.

13. During boiler operation, the Flame1 LED in respective corner processor

module will be ON when the following conditions are met.

a. Flame intensity is more than PI set value AND

b. Coal frequency is more than F1 set value AND

c. No Fault condition exists (Fault LED OFF)

Flame1 LED will switch OFF, if any one of the following conditions is met.

a. Flame intensity is less than PO set value OR

b. Coal frequency is less than F1 set value OR

c. Any fault conditions exits. (Fault LED ON)

14. During boiler operation with oil, the Flame2 LED will be ON when the

following conditions are met. The relay output is available at TB Nos. 6,7 & 8

in the respective corner.

a. Flame intensity is more than PI set value AND

b. Oil frequency is more than F2 set value AND

c. No fault condition exists. (Fault LED OFF)

Flame2 LED will switch OFF, if any one of the following conditions is met.

a. Flame intensity is less than PO set value OR

b. Oil frequency is less than F2 set value OR

c. Any fault conditions exits. (Fault LED ON)


15. 4-20 mA current output is available corresponding to 0 100% of flame

intensity in respective corner at TB Nos. 9 & 10. If any fault condition exists,


(Fault LED ON), this current output will go to 4 mA irrespective of the intensity

level shown in display.

16. The 2/4 Flame LED indication in 2/4 flame module represents the presence of

fireball during coal firing. This LED will be ON, whenever, two or more

corners Flame1 (coal flame) show flame. The relay outputs in two sets of

contacts are available at TB Nos.1,2&3 and 4,5 & 6 of TB5.

17. If any fault LED is ON in any of the processor modules, Fault LED in 2/4

module will be ON. The Fault relay will get energized. The relay output is

available in TB Nos. 7&8 of TB5.

18. RS232-C serial communication output is available at TB Nos.10, 11 & 12 in

TB5. This can be used to communicate the flame parameters to Personal

Computer.

8.5 DIP Switch Setting Procedure (Refer Figure 7B ) :

Switch OFF the power supply to BHELSCAN system. Remove the flame

processor module at corner 1.

Locate S1 DIP switch as shown in Figure 7B for intensity pull-in value. Set 40 by

keeping the individual switch as below.

DIP switch position: 8 7 6 5 4 3 2 1

Setting status OFF OFF ON ON OFF OFF OFF OFF

Locate S2 DIP switch as shown in Figure 7B for intensity pull-out value. Set 30 by



Setting status OFF OFF OFF ON ON ON ON OFF

Locate S3 DIP switch as shown in Figure 7B for coal frequency set value. Set 05 by



Setting status OFF OFF OFF OFF OFF ON OFF ON



Locate S4 DIP switch as shown in Figure 7B for oil frequency set value. Set 30 by



Setting status OFF OFF OFF ON ON ON ON OFF

For other values of above settings, convert the decimal value to 8 bit binary and

set the DIP switches accordingly. For 1 status, the switch shall be in ON position.

Repeat the same procedure for settings in other flame processor modules. Insert

the modules into the respective location and switch ON the AC power supply. Verify the

set values in individual flame processor module by selecting the display using mode PB.

8.6 Calibration of Scanner Head Electronics : The scanner head electronics are adjusted during manufacturing. If a component on the

electronics card is replaced, field adjustment of the gain and offset potentiometers and

dark furnace bias will be required.

8.6.1 Gain and Offset Adjustment : The flame scanner assembly must be removed from its guide pipe. Turn both power

supplies off, disconnect the cable and open the head assembly for access to the

scanner head electronics card.

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, 1/8W, 1%)

c. 1 A dc current source (1V dc in series with a resistor; 1M, 1/8W, 1%)

d. Small soldering pencil


Disconnect the positive lead of the photodiode from its terminal. Simulate a photodiode

input by connecting the 1 mA dc current source to the photodiode terminals. Connect

the digital volt meter (DVM) between signal C and common D terminals on the


electronics card; then reconnect the scanner cable. Turn the scanner power supply on

and adjust potentiometer R101 to provide a reading of 0.000 V on the DVM.

Replace the 1 mA dc current source with a 1 A source and adjust potentiometer R103

to provide a reading of 1.000 V on the DVM. Disconnect the scanner cable and test

leads, reconnect the photodiode and proceed with the dark furnace bias adjustment.

8.6.2 Dark Furnace Bias Adjustment : To ensure proper operation of the BHELSCAN relatively uniform voltages must be input

to the chassis by the four associated scanner assemblies during dark furnace, no fire

conditions. Total absence of a signal from the scanner assembly would generate a fault

condition. To prevent this from occurring, feedback LED is installed on the scanner

head electronics card adjacent to photodiode.

The flame scanner assembly should be removed from its guide pipe and the scanner

cover plate should be installed. Completely block all light from the furnace end of the

fibre-optic cable and open the scanner housing.

Connect a digital voltmeter (DVM) between the signal C and common D terminals on the

electronics card.

Reconnect the scanner cable to the scanner assembly. The power supply switch should

be turned on. Work under a dark cloth to reduce he amount of ambient light admitted to

the scanner head. Adjust potentiometer P114 so that the DVM reads approximately

2.1V. This completes the scanner head electronics adjustments. Disconnect the test

leads, reassemble the scanner assembly and reinsert it in the guide pipe.

All four scanner channels, under dark furnace conditions, should have a similar intensity

meter reading.

9. FLAME SCANNER CABLE


This is a 1.3 sq.mm., Annealed, Tinned, Copper Conductor, Elastomeric/

Thermoplastic/Equivalent material Insulated, Twisted pair, Aluminium Backed Mylar


Tape Shielded with Drain Wire, 2 such pairs laid up, Over all Aluminium Backed Mylar

Tape Shielded with Drain Wire, Elastomeric / Thermoplastic/Equivalent material Over all

Sheathed Cable.

Colour Code for Core/Pair :-

First Pair Red & Black This Pair is used to connect Power Supply to field.

Second Pair Green & White This Pair is used to connect Signal to Amplifier.

9. MAINTENANCE AND TROUBLE SHOOTING :


9.1 Scanner Head :


The scanner head at the front of the fibre-optic scanner assembly has an

opening for viewing the flame. With certain types of coal, slag may eventually build up

and cover the opening. The scanner head should be inspected periodically and cleaned,

if necessary. Hence, an inspection program should be established based on operating

experience.

9.2 Fibre-Optic Cable : The collimator shield and the lens on the end of the fibre-optic cable should also

be inspected periodically for cleanliness. The degree of fouling will depend on the type

of fuel used, the plant operating characteristics and the cleanliness of the cooling air. An

inspection program should be established, based on operating experience. Always

check the shield and lens when the scanner head is inspected.

9.3 Electrical Components : The electronic modules do not require periodic maintenance. If trouble does

occur, the best way to troubleshoot the system is to substitute modules in the card rack

assembly and/or head electronic modules. Modules are to be inserted only in the slots

designated for them.

If the scanner chassis is not working, check whether lamps in the power supply

module corresponding to AC power ON, -15V ON, +15V ON and +5V ON. If AC power

is not ON, check the fuse F01 in the power supply mother board and the incoming AC

power. If the DC supplies are not ON, check the corresponding fuses at the rear side of

the power supply module. If the fuses are alright and still any one of the above DC

voltages are not present, power supply module has to be replaced.


In flame processor module, fault lamp should be OFF. If this lamp is ON, check

the fuses corresponding to +15V and 15V feeding to head electronics in the processor

mother board. If the fuses are healthy, then check the continuity of flame scanner cable

connection between the terminal block and the head electronics in the field. If continuity

is also alright, then head electronics may need recalibration or replacement. For any


other fault in this module like no response for mode selection PB, improper display, etc.,

the module is to be replaced.

In 2/4 flame module, the fault lamp should be OFF for normal operation. If the

fault lamp is ON, then fault lamp in any one or more of the flame processor modules may

be ON. If that module is attended, this fault may vanish. If this fault persists even then,

2/4 flame module may need replacement.


Do not insert or pull out any module from the connector when power is ON. This

may damage the module. If any module has to be removed for examination or changing

the settings, it is safe to switch OFF the power by operating the toggle switch SO1 in the

power supply mother board and wait till all the lamps in the power supply module go

OFF. Then remove or insert the module and then switch ON the toggle switch SO1 if

needed to power up the system.

Figure - 6B BHELSCAN GENERAL ARRANGEMENT

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)

Figure - 8B

BHELSCAN 2/4 MODULE

2/4 Relay

Fault Relay

Figure - 9B

BHELSCAN POWER SUPPLY MODULE (FRONT VIEW)

Figure - 9C BHELSCAN POWER SUPPLY MODULE (REAR VIEW)

FIGURE 11D:BHELSCAN TB ARRANGEMENT (REAR MOUNTING)

Cust. No.:03618.2Cooling air8.3Electrical components9.1Scanner head9.3Electrical componentsFigure-1 : Windbox arrangement showing Flame scanner system

3.1Flame Scanner Guide Pipe AssemblyCAUTIONDO NOT REMOVE ANY MODULE WITH POWER ONFLAME SCANNER

8.1Mechanical Components :8.2Cooling Air :CAUTION

Power supply mother boardTB No.

Processor mother boardTB No.8.6Calibration of Scanner Head Electronics :8.6.1Gain and Offset Adjustment :8.6.2Dark Furnace Bias Adjustment :

Colour Code for Core/Pair :-The scanner head at the front of the fibre-optic scanner assembly has an opening for viewing the flame. With certain types of coal, slag may eventually build up and cover the opening. The scanner head should be inspected periodically and cleaned, if neFibre-Optic Cable :The collimator shield and the lens on the end of the fibre-optic cable should also be inspected periodically for cleanliness. The degree of fouling will depend on the type of fuel used, the plant operating characteristics and the cleanliness of the coolElectrical Components :The electronic modules do not require periodic maintenance. If trouble does occur, the best way to troubleshoot the system is to substitute modules in the card rack assembly and/or head electronic modules. Modules are to be inserted only in the slots dIf the scanner chassis is not working, check whether lamps in the power supply module corresponding to AC power ON, -15V ON, +15V ON and +5V ON. If AC power is not ON, check the fuse F01 in the power supply mother board and the incoming AC power. If thIn flame processor module, fault lamp should be OIn 2/4 flame module, the fault lamp should be OFF for normal operation. If the fault lamp is ON, then fault lamp in any one or more of the flame processor modules may be ON. If that module is attended, this fault may vanish. If this fault persists evDo not insert or pull out any module from the connector when power is ON. This may damage the module. If any module has to be removed for examination or changing the settings, it is safe to switch OFF the power by operating the toggle switch SO1 in the

FIGURE11d.pdfFIGURE 11D:BHELSCAN TB ARRANGEMENT \(REAR MOU

flame scanners

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