Boiler Interlocks 725948

BOILER INTERLOCKS ID FAN START 1) Suction damper closed condition 2) Discharge damper closed condition 3) Drum level above 20% ID FAN TRIP PERMISSIVE 1) 2) 3) 4)

Drum level below 20% Furnace draft very high -25 mmwc ID fan bearing temp high ID fan bearing vibration high

FD FAN START 1) Suction damper closed condition 2) Discharge damper closed condition 3) Any one of ID fan should be in run condition TRIP PERMISSIVE 1) Furnace draft very low +30 mm wc 2) Boiler steam pressure high above 109 Bar 3) Bearing temperature and vibration high SA FAN START PROCEDURE 1) 2) 4) 5)

Anyone ID fan running condition Anyone FD fan running condition Suction damper closed condition Discharge damper closed condition

TRIP PERMISSIVE 1) FD fan trip 2) All Drag chain feeder trip DRAG CHAIN FEEDER START PROCEDURE 1) Mech spreader running condition 2) FD & SA fan running condition DRAG CHAIN FEEDER TRIP 1) FD fan trip 2) Boiler pressure high high above 109 bar FEED PUMP START 1) ACW cooling water pressure above 2.5 bar 2) Discharge valve closed condition 3) Deaerator level above 25%

4) DP of strainers should be low TRIP 1) 2) 3) 4)

Bearing temp and vibration high Deaerator level very low Strainer DP very high Cooling water pressure very low

STANDARD OPERATING PROCEDURE FOR BOILER                                

Get field operators clearance Get electrical and instrumentation team clearance WTP team water level and quality All manhole doors should be in closed condition Ensure all vent valves are in open condition Ensure all drain valves are in closed condition Check the drum level and maintain 30% water level in drum All control valves and dampers, fans put in MANUAL operation mode Check the instrument compressor pressure and maintain above 6.5 bar Check the travelling grate and dump the firewood inside the furnace Spray little diesel over the firewood and fire it Start the ID fan and maintain furnace pressure + 3 mmwc Start one of FD fan and pick up the fire. Maintain the furnace temp gradually Once the furnace temperature reached 350 – 400 deg c, switch on the mech spreaders Start the SA fan and Drag chain feeders Start coal feeding and increase the furnace temperature Once the drum pressure reached 5 bar close the drum air vent and line vents Maintain the start up vent in Open condition Before MSSV, all the drains are in open condition When the steam pressure reaches 40 Bar, Open the MSSV by valve After MSSV, open all the drains Make warm up of all MSSV steam line TG inlet by valve in open condition and TG warm up vent in open condition Maintain Deaerator level 60% Check the ACW pump and maintain the discharge pressure above 2.5 bar Start the feed pump and maintain the drum level 40% by using 30% feed water control valve When the steam pressure reaches 75 Bar open the MSSV slightly. Ensure all the header drain valves are in open condition Maintain CDSH draining and warm up Gradually close the start up vent valve before turbine side Once the rated pressure reaches 105 Bar and 530 Deg C Connect the main steam in CDSH

STANDARD OPERATING PROCEDURE FOR TURBINE                    

Ensure the oil temp is 38 Deg c otherwise switch on the heater Before 4 hrs in prior to start the TG, Bar ring gear should be started Maintain the CST level 60% Any of CEP started All interlocks should be in NORMAL mode Check MOT level Check OHOT level When MSSV integral by valve open, after that open TSSV and TG warm up vent in open condition PRDS steam line draining and warm up should be done When the steam pressure reached 75 Bar and temp 530 Deg C, Start vacuum pulling by Hogger @ 10.5 bar steam pressure Hogger vacuum breaker valve should in Closed condition When vacuum reaches 0.6 kg/cm2, allow gland sealing steam @ 0.15 ata When vacuum reaches 0.85 kg/cm2, start any 2 ACC fans Turbine faults reset to be done in DCS Start RUN Command in TG 35 minutes allow the TG in idle speed When the TG reaches rated RPM 6800, get electrical team clearance for Synchronizing After Sync, load has to be raised, close all the drain valves Once the TG load reaches 7 MW. Charge deaerator with 3 ata steam When the TG load reaches 12 MW , charge the HP heater

TRIP PARAMETERS IN TG                  

Main steam temperature VERY LOW 70 Bar Main steam temperature VERY HIGH 114 Bar Main steam temperature VERY LOW 385 C Main steam temperature VERY HIGH 551 C Exhaust temperature VERY LOW 105 C Exhaust temperature VERY HIGH 120 C No load trip 2.5 M Turbine exhaust steam pressure VERY LOW -0.6 Bar Lube oil pressure VERY LOW 1.8 Bar Control oil inlet pressure VERY LOW 7.5 Bar Turbine front and rear shaft vibration VERY HIGH 109 microns TG gear box HS DE & NDE vibration VERY HIGH 125 microns TG Gear box LS DE &NDE vibration VERY HIGH 150 microns Generator front & rear shaft vibration VERY HIGH 100 microns Turbine thrust temperature VERY HIGH Deg C Turbine front and rear bearing temperature VERY HIGH 120 deg c Gear box HS & LS De/NDE bearing temperatures VERY HIGH 100 deg c Alternator front and rear bearing temperature VERY HIGH 90 deg c

 Turbine over speed trip 7480 RPM  Axial displacement VERY HIGH 0.6 mm  Hot well level VERY HIGH 80% Fuel specifications Coal Spent wash Bed material specifications Start up procedure DP details 1) 100% speed of FD fan & 100% opening of damper will be 750 mmwc 2) Under no load condition (no bed material on the bed) DP will be 200-250 mmwc 3) Under loaded condition, the DP will be 700-750 mmwc Method of preparation of the boiler for start up a) b) c) d) e) f) g) h)

Close all the manholes/peep holes/ inspection doors Maintain the water level in drum 35% Move the bed material to the furnace floor. 170 bags – 8.5 tons approx Check the bubble caps and make sure that the bubble caps are free from any surface defects and the holes are very clean without any choke Conduct a trial by running FD fan and make sure there is no leakage in dampers Moved bed materials are to be filled up into the furnace up to 350 mm height above the bubble cap Start the FD fan and conduct fluidization test, DP test. If any dead zones found in fluidization test, the corresponding zone bubble caps are to be checked and cleaning to be conducted After completing the DP test, give clearance for charging the charcoal 80% dry and 20% mixed with diesel (Approx 650 kgs)

Troubleshooting of Boiler Expected problems in AFBC Boiler a) Bed temperature drop Possible reason: 1) Less FD air 2) Low fuel feeding 3) Air nozzle problem 4) Thermocouple check Remedy: 1) Increase air flow corresponding to fuel feeding 2) Replace bed material 3) Replace nozzle b) Poor fluidization

c)

d)

e)

f)

g)

h)

Possible reason: 1) Bed height less 2) Bed mat’l qty (Over size than the recommended) 3) FD air less 4) Nozzle block 5) Clinker formation time Remedy: 1) Recharge bed material 2) Adjust the air flow corresponding to the fuel input 3) Check nozzle Increased bed temperature Possible reason: 1) Fuel high 2) Less air Remedy: Clinker formation Possible reason: 1) Uneven bed temperature 2) Poor fluidization 3) Size of bed material 4) Fuel dump on the bed 5) Poor distribution of air over the bed 6) Low bed Remedy: 1) Drain the bed material and recharge it Furnace turbulence Possible reason: 1) More air Remedy: 1) Maintain air fuel ratio Dead zone in compartments Possible reason: 1) Air nozzle problem 2) Dumping of fuel in the zone Remedy: 1) Replace air nozzle 2) Avoid dumping of fuel Back fire Possible reason: 1) Downstream choking 2) Air ingress Remedy: Increased SH temperature Possible reason: 1) Too much fuel feeding 2) Sudden load fluctuation 3) Furnace temperature high 4) SA less 5) Control system problem Remedy:

1) Reduce the fuel 2) Put attemperator in manual mode and bring down the temperature