Boiler Protection
Boiler Protection
Boiler Protection
Both FD fans OFF. Both ID fans OFF. Inadequate water wall circulation for more than 5 seconds. Loss of Reheat Protection for greater than 10 seconds. All BFPs tripped. Drum level very high for more than 10 seconds (2/3 logic). O Drum level very low for more than 10 seconds (2/3 R logic). Furnace pressure very high (2/3 logic). Furnace pressure very low (2/3 logic). Loss of all fuel. All feeders OFF and loss of AC Supply to the elevation in service. Unit flame failure. Loss of 24 V DC for more than 2 seconds. Both Secondary APHs OFF. Loss of 220 V DC Supply for more than 2 seconds.
MFT RELAY
Arming:
Always armed Logic: Both ID Fans OFF Contact sensed by MFT panels Purpose: Anticipatory protection to prevent furnace pressurization Loss of furnace pressure control and balanced draft Protection Delay: 0 sec INSTANT. Protection Check: Simulate the signals from ID Fans Electrical Control Circuit
Arming:
Always armed Logic: Both ID Fans OFF Contact sensed by MFT panels Purpose: Anticipatory protection to prevent furnace pressurization Loss of furnace pressure control and balanced draft Protection Delay: 0 sec INSTANT. Protection Check: Simulate the signals from ID Fans Electrical Control Circuit
4. FLAME FAILURE
Arming: Any Feeder Proven for 2 sec. Logic: All Elevations A to K voted NO Flame. Eg. Elevation A voted no flame means: (AA 3/4 fireball scanners sense no flame AND AB 3/4 fireball scanners sense no flame AND AB 2/4 oil guns not proven in service) OR Feeder A Not Proven for 2 sec. Purpose: Stop firing under unstable flame fireball conditions. Protection Delay: 0 sec INSTANT. Protection Check: Simulate feeder proven status without any oil in service.
Protection Delay: 10 sec. Protection Check: Simulate OFF contact of all BFP from BFP control panel
PURGE PERMISSIVES
All HFO nozzle valves closed All pulverisers OFF All feeders OFF No MFT condition present a All scanners senses no flame All Auxiliary Air dampers modulating N Both PA fans OFF d All Mill HAGs closed Air flow more than 30% and less than 50% HFO trip valve is closed Wind box to furnace DP is adequate
To fsss
Thank You