Flame Scanner.ppt
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The document provides information on BHELSCAN, a microcontroller-based flame sensing system that detects the presence of fire in a boiler. It consists of a scanner head assembly located in the boiler and a chassis with electronic modules located in the control room up to 200 meters away. The scanner head detects visible light from a flame and converts it to an electrical signal. The system can recognize coal and oil flames based on light fluctuations. The electronic modules process the flame signals and provide outputs on flame intensity and status. The document describes the various components, modules, settings, calibration process and maintenance of the BHELSCAN system.
Flame Scanner.ppt
- 2. INTRODUCTION â˘PRINCIPLE PURPOSE OF FLAME SAFEGUARD SUPERVISIORY SYSTEM IS TO ENSURE THAT IT IS SAFE TO LIGHT THE BOILER AND CONTINUE BOILER OPERATION. â˘IT IS ALSO USED FOR BOILER SHUTDOWN. â˘ACCURATE DETECTION OF A FIRE IS ONE OF THE MOST IMPORTANT TASKS OF FSSS. â˘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 âBHELSCANâ uses visible spectrum for flame sensing.
- 3. â˘AN IDEAL FLAME SCANNER DETECTS A FLAME OF INTEREST WHILE TOTALLY IGNORING OTHERS AND IS UNAFFECTED BY CHANGES IN AMBIENT CONDITIONS. â˘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 : 19â Rack with 3U size cards
- 9. MECHANICAL COMPONENTS ď Stationary part -- âflame scanner guide pipe assemblyâ ď removable part--âflame scanner assemblyâ. 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: â˘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. â˘FLEXIBLE METAL HOSE:- Houses the fiber optic cable â˘RIGID PIPE:- Houses the fiber optic cable â˘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:- ď The electrical components of the BHELSCAN system are contained in the scanner housing assemblies and the card rack assembly. ď A photo diode located in each scanner housing assembly converts visible light (flame signal) observed by the scanner head into an electrical equivalent signal. ď The scanner housing output signal is an AC current signal, which is sent to the card rack assembly for processing. ď 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. ď An intensity signal indicates the magnitude of the flame brightness on 2½ digit LED display(Range is 0-100%). ď 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 â GENERAL ARRANGEMENT
- 19. Figure - 7B BHELSCAN âFLAME 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 ď This receives digital signals corresponding to âFlame 1 ONâ from all 4 flame processor module. ď If two or more than two âFlame 1â inputs are available, 2/4 Module signals presence of fireball. ď However , for fireball indication in DCS , corresponding feeder âONâ bit is taken in an AND Gate along with the above mentioned 2/4 Logic.
- 21. Figure - 8B BHELSCAN â2/4 MODULE 2/4 Relay Fault Relay
- 22. Figure - 9B BHELSCAN âPOWER SUPPLY MODULE (FRONT VIEW) Figure - 9C BHELSCAN âPOWER SUPPLY MODULE (REAR VIEW)
- 23. Power Supply Module ď This will work in 110V AC or 230V AC as given in the nameplate 1. +15 V DC 2. â15V DC 3. +5.0V DC ď 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 â00â 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 â00â flickering. 4. When Power supply +15Vdc fuse blown - flashing 100%. 5. When Power Supply -15Vdc fuse blown âAny 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 â40â 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 ÎźA 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 âCâ and common âDâ terminals on the electronics card. Turn the scanner power supply âonâ and adjust potentiometer R101 to provide a reading of 0.000 V. Replace the 1 mA dc current source with a 1 ÎźA 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 : â˘The scanner head should be inspected periodically and cleaned, if necessary. Fibre optic cable: â˘The collimator shield and the lens on the end of the fibre-optic cable should also be inspected periodically for cleanliness. Electrical components: â˘The electronic modules do not require periodic maintenance. â˘If AC power is not ON. â˘If DC supplies are not ON. â˘In flame processor module, fault lamp should be OFF. â˘In 2/4 flame module, the fault lamp should be OFF. â˘Do not insert or pull out any module from the connector when power is ON.
- 33. THANK YOUâŚ.