419687556-Boiler-Interlock-Protection-System.pptx

Boiler all details ppt presentation

1. JAYPEE BINA THERMAL POWER PLANT 2X250 MW BOILER INTERLOCK & PROTECTION SYSTEM By Rahul Chauhan Control & Instrumentation

2. OBJECTIVE OF CONTROL & INSTRUMENTATION SAFE OPERATION OF PLANT LOWEST COST OF GENERATION LONGEST EQUIPMENT LIFE MINIMUM ENVIROMENTAL EFFECT MAXIMUM EFFICIENCY

3. INTRODUCTION FSSS means furnace safeguard & supervisory system , the system which is used in almost all types of boiler. The system has been designed to offer maximum protection and to ensure the execution of a safe, orderly operating sequence in the start up and shutdown of fuel firing equipment. FSSS is designed to perform the following functions:

4. Prevent any fuel firing unless a furnace purge sequence has first been completed. Monitor and control the proper component sequence (Manual or Automatic) during start-up and shut-down of fuel firing equipment. Make continued operation of fuel firing equipment subject to certain safety interlocks remaining satisfied. Provide component status feedback to the operator and in some cases, to the unit control system. Provide flame supervision when fuel firing equipment is in service and effect a fuel trip upon certain adverse operating conditions. Initiate a fuel trip when certain abnormal operating condition exists

5. Heavy Oil (HO) fired boiler with coal as the primary fuel. Light Oil (LO) as the start-up fuel, Heavy Oil as the fuel for warm up and stabilisation. Three elevations of high energy arc (HEA) igniters. Previously Three elevations of oil guns with provision for firing LDO oil in AB elevation only, HFO oil in AB, CD & EF elevation. Now modification has done that provision of firing LDO oil in all 3 elevation i.e AB, CD & EF elevation. With these modification Desk Engineer will able to minimize the Boiler Light-up to Synchronization time. Six Pulverisers, serving six elevations of 24(6X4) coal nozzles in Burner block assembly. FSSS provided for this project is designed for a natural circulation :

6. FURNACE PURGE Furnace purging is done to remove all unburnt particles which may have been inside the furnace during earlier unit operation. Before Boiler is lighted up Furnace purge is done for which following interlocks should be satisfied: Establish 230/110V AC & 24/220V DC power to FSSS and the related equipment. Establish normal drum level (-15 mm from NWL). Run at least one ID and one FD fan in service. Establish Airflow between 30% and 40% MCR i.e 300 to 400 TPH through the furnace. Press the purge start push button from HMI.

7. If the "Purge ready” green light signal does not come on after the above conditions have been completed. Check other these condition : The light oil trip valve is proven closed. All the light oil nozzle valves are proven closed. The heavy oil trip valve is proven closed. All the heavy oil nozzle valves are fully closed. All PA Fans are off. All feeders are off. All hot air gates are fully closed, All the flame scanners sense "No Flame". No boiler trip command is present. All auxiliary dampers are modulating(open condition). At the end of the five minutes, the boiler trip circuit is reset, provided no boiler trip command is present.

8. SELECTION OF LIGHT OIL Oil elevation AB is provided with Light Oil / Heavy Oil firing. Light oil or Heavy oil firing can be selected from the console insert by pressing the appropriate push button provided in graphic. LIGHT OIL TRIP VALVE (LOTV) CONTROL Once the Boiler trip circuit is reset and all the light oil nozzle valves are proven closed, pressing the light oil trip valve "open" push button, will open light oil trip valve provided the light oil header pressure is adequate.

9. LIGHT OIL TRIP VALVE (LOTV) Open permissive: All LONVs are closed. Furnace Purge Completed & MFT reset. Light oil header pressure Adequate >15.6kg/cm2. Unit 24 V DC power available. Protection close: Light oil header press V. Low < 4.2kg/cm2. Atomising air pressure V. Low < 3.5kg/cm2. MFT acted The LOTV will be commanded to close on loss of +24V DC.

10. OIL ELEVATION START PERMIT Select light oil or Heavy oil firing. LOTV or HOTV valve proven fully open. Purge Completed & MFT reset. Burner Tilt Horizontal & Air flow < 40% MCR.(Cold condition) OR Any oil elevation in service(warm up condition) or Any feeder on.(Running condition) Local maintenance switch in remote position. Oil gun engaged. Scavenge valve closed. Manual isolation valve open.

11. LDO START SEQUENCE To place the light oil guns in service following sequence is defined in four steps: HEA Rod advance command. Open air atom valve. Open LONV valve and HEA Spark command. Step complete.

12. TO TAKE LDO OIL GUN IN – PAIR MODE To place the light oil guns in service “Oil elevation start permit” should be available. LDO oil can be fired at EL. AB & in pair basis. Corners 1 and 3 make one pair, while corners 2 and 4 make the other pair. The corners making up a pair are diagonally opposite. By pressing the associated pair start command ( i.e corner 1&3 or 2&4), will initiate a 70 seconds start time to place the associated pair of LDO oil guns in service . When corner -1&3 is selected a start command is sent to oil corner 1, Fifteen seconds later, a start command is sent to oil corner 3 corners.

13. When HEA rod is advanced and the atomising Air valve is fully open and LONV valve gets open command & HEA igniter gets command for sparking. 15 seconds later, HEA igniter advance and spark command is removed. If the flame is established within the above 15 seconds then the oil gun is said to have been successfully placed in service and will continue to operate. If the flame is not established by the end of 15 seconds, corner trip will be initiated which will close the oil nozzle valve & atomising valve of the particular corner . Flame no flame condition

14. TO TAKE OIL GUN IN ELEVATION MODE

15. HEAVY OIL TRIP VALVE CONTROL HOTV START PERMIT All HONVs are closed. Purge Completed & MFT reset. Heavy oil header press Adequate > 19.3kg/cm2. Heavy oil header temp Adequate > 110 Deg.C

16. HEAYY OIL START SEQUENCE Heavy oil start sequence is defined in four steps: HEA Rod advance command. Open atomizing steam valve. Open HONV valve and HEA Spark command. Step complete.

17. OIL SHUTDOWN SEQUENCE Heavy oil shutdown sequence is defined in five steps: Close cmd to HONV valve. Open atomizing steam valve. Open Scavenge valve & HEA Rod advance & Spark Cmd for 15 secs. A 5 min.Scavenge period is started. Close Scavenge valve & atom. steam valve. Step complete

18. BOILER PROTECTIONS

19. PROTECTION OF BOILER: TO detect the abnormal condition by constantly measuring the various parameter under normal and faulty condition . If any abnormality happened trip the boiler to prevent from major damage. NEEDS OF INTERLOCK & PROTECTION To avoid operational faults Equipment safety To avoid accidents To avoid systems disturbances

20. BOTH ID FAN TRIP IDF – A Off (Off Feedback) IDF – B Off (Off Feedback) PURPOSE : Protection to prevent furnace pressurization BOTH FD FAN TRIP FDF – A Off (Off Feedback) FDF – B Off (Off Feedback) PURPOSE : Protection to prevent reducing firing condition. MFT MFT AND Logic Gate AND Logic Gate

21. DRUM LEVEL VERY LOW Tripping value = < - 225 mmwc Alarm = < -125 mmwc Time delay = 5 sec. PURPOSE : To prevent water wall tubes starvation . DRUM LEVEL VERY HIGH Tripping value = > + 225 mmwc Alarm = > + 125 mmwc Time delay = 10 sec . PURPOSE : To prevent water carry over to super heater header and to turbine. T1 T2 T3 2/3 Logic MFT Transmitters Range = - 425 to 762 mmwc

22. FURNACE PRESSURE VERY HIGH Tripping value = > + 150 mmwc Alarm = > + 75 mmwc PURPOSE : To stop fuel firing under explosive tendency of furnace , prevent furnace structural distortion FURNACE PRESSURE VERY LOW Tripping value = < - 175 mmwc Alarm = < - 100 mmwc PURPOSE : To stop fuel firing under implosive tendency of furnace , prevent furnace structural distortion 2/3 Logic 2/3 Logic MFT MFT V.High 1 V.High 2 V.High 3 V.Low 1 V.Low 2 V.Low 3 2/3 Logic 2/3 Logic MFT MFT V.High 1 V.High 2 V.High 3 V.Low 1 V.Low 2 V.Low 3 Switches Switches

23. LOSS OF FUEL TRIP The loss of fuel trip circuit becomes armed once any one OIL nozzle valves lifts ON from closed position in any elevation. AND LOGIC GATE LOSS OF FULE TRIP ARMING ALL FEEDER OFF ( FEEDBACK OFF) HOTV IS NOT OPEN OR ALL HONV CLOSED LOTV IS NOT OPEN OR ALL LONV CLOSED

24. Once the trip circuit is armed, loss of fuel trip will occur if, All feeders are off. AND HO trip valve is TRIPPED OR All HO nozzle valves closed. AND LO trip valve TRIPPED OR Elev. AB All LO nozzle valves closed. PURPOSE : Back protection to trip remaining equipment .

25. FLAME FAILURE TRIP ABOUT FLAME SACNNAR visible light flame monitoring system is a microprocessor based system designed to monitor Oil and Coal flame. Light is transmitted from the wind box through a fibres optic light guide and converted to an electrical signal by a photodiode. Both the flame intensity and flame pulsation frequency are amplified by an electronic circuit and further it is converted as current signal to process in the remote amplifier unit. The system shall be incorporated with burner sequencing and flame monitoring protection logics of Furnace Safety System. Intensity Pull In (%) 40 Intensity Pull Out (%) 30 Coal freq. set value (Hz) 5 Oil freq. Set value (Hz) 30 EL . B VOTED NO FLAME EL . A VOTED NO FLAME

26. LOGIC DIAGRAM 2 S ANY FEEDER PROVEN FLAME FAILURE TRIP ARMING EL . F VOTED NO FLAME EL . E VOTED NO FLAME EL . D VOTED NO FLAME EL . C VOTED NO FLAME EL . B VOTED NO FLAME EL . A VOTED NO FLAME AND LOGIC GATE

27. FOR EXAMPLE ELEVATION A VOTED NO FLAME Elevation AB 3 out of 4 Fireball scanners shows no flame AND elev. AB HO/LO 2 out of 4 nozzle valves not open . OR Feeder A is not proven ( Off Feedback) OR Elevation A started and loss of 110v AC power (2 sec time delay)

28. REHEATER PROTECTION REHEATER PROTECTION ENABLE (a) Boiler drum pressure > 8.2 kg/cm2 (b) Any feeder on (c) Boiler firing PROTECTION : 1 WHEN BOILER IS 'WORKING / REHEATER PROTECTION ENABLE (a) GENERATOR CIRCUIT BEAKERS OPEN &. BOTH SATISAFIED (b) HPBP OR LPBP VALVES REMAIN CLOSED <2% 2 WHEN BOILER IS 'WORKING / REHEATER PROTECTION ENABLE (a) TURBINE HP STOP VALVES OR CONTROL VALVES CLOSED & BOTH HPBP CV < 2 % OPEN. (b) TURBINE LP STOP VALVES OR CONTROL VALVES CLOSED & BOTH LPBP CV < 2 % OPEN. BOILER SHALL BE TRIPPED AFTER 10 Sec . contact Contact Contact 2/3 Logic MFT

29. LESS THAN FIRE BALL & 110V AC POWER FAIL If all feeders are off AND Elevation AB/CD/EF any one having loss of 110v AC upto 2sec.

30. LOSS OF 220 V DC If 220v DC supply fails upto time 2 sec. 220v DC supply used main oil valve HOTV , HORV , LOTV & scanner emergency damper. LOSS OF 110 V AC AB/CD/EF if any one elevation started & 110v AC power fails upto 2 sec. 110v AC supply used in all OIL nozzels valve , HEA Exciter , Feeder outlet gate , All hot air gates , mill discharged valve.

31. LOSS OF 24V DC 24v DC is used for functioning of DCS cards and field instruments ( Transmitters , switches , I/P converter ) 24v DC is used for the operation of important field drives HOTV , LOTV , scanner air fan dampers and seal air fan dampers. 24v DC is used for the operation of all nozzle valves. PURPOSE : If 24V fails , the DCS system cannot execute any logic . TOTAL AIR FLOW < 30% If (secondary air + primary air) flow < 300 TPH.

32. MFT NETWORK FAILURE If any 2 DPU cards out of 3 of MFT panels go into failed status it will initiate MFT Protection. PURPOSE : This ensure that at least 2 DPU cards are in healthy condition at any point of time when boiler is in service . Failure the DPU cards leads to unsafe condition . 2/3 Logic DPU2 DPU3 DPU1 MFT (DPU = DIGITAL PROCESSING UNIT)

33. BOILER TRIP THROUGH UCB PUSH BUTTON

34. THANK YOU