This document outlines the logic and conditions for a pulverized coal fired boiler. It describes 17 conditions that can trigger a manual fire trip (MFT), including issues with fans, pumps, pressures, and flame detection. It also explains the requirements and process for furnace purging after an MFT occurs. This includes conditions that must be met and interlocks in place. Additionally, it provides the process and permissives for testing for oil leaks in the heavy and light fuel oil supply pipes.

1. For
PULVARISED COAL FIRED BOILER
BY
ASHVANI SHUKLA
MANAGER(C&I)
RELIANCE

2. Common Logic
 1.MFT
 2.Furnace Purging
 3.Oil Leak Test
 4.OFT
 5.Oil System Normal
 6.Furnace Firing permissive Condition
 7.Runback
 8.Post trip purge excursion protection

3.  Any following condition generate, touch off
MFT or generate the pulse or PF contact.
 1. Manual MFT
 Both MFT pushbuttons are depressed at the
same time.
 Two signals are to trip MFT cabinet. Two
signals (AND) are to DCS system to trip.
 2. Both FDFs tripped
 FD Fan 1 trip
 FD Fan 2 trip

4.  3.Both ID Fans tripped.
 1.ID Fan 1 tripped.
 2.ID Fan 2 tripped.
 4. Both APHs tripped.
 1.APH A pass should be tripped
 2.APH b pass should be tripped.
 5. All BFP tripped.
 1.BFWP 1 tripped.(TD)
 2.BFWP 2 tripped.(TD)
 3.BFWP 3 tripped.(MD)
 6. Lost primary air : Both PAFs tripped when
any mill in service.
 1.PA Fan 1 tripped.
 2.PA Fan 2 tripped.

5. 7.Lost Flame Scanner cooling air.
Both cooling air fans tripped
or outlet main pipe press LL 2/3, with delay
of 10s.
8. Total airflow is <25%BMCR (2 out of 3)
total airflow is <25%(PA +SA air flow)
9. 1.Drum level HH (2 out of 3, delayed
20s)
 2. Drum level LL (2 out of 3, delayed
20s)
10. 1.Furnace negative pressure HH (2 out
of 3)
 2. Furnace negative pressure LL (2 out
of 3)

6.  11.Fire failure
 Any oil burner ignite fail up to 3 times
 12. Loss of fuel trip
 1.When any oil burner ever set in service.
 2.all oil valve closed（HFO and LDO） or
OFT.
 3.all PULV stopped.
 13. Unit flames failure (AND)
 Any coal feeder has run 120 second
 No oil elevations is in service
 A coal elevations no flame(3 out of 4)
 B coal elevations no flame(3 out of 4)
 C coal elevations no flame(3 out of 4)
 D coal elevations no flame(3 out of 4)
 E coal elevations no flame(3 out of 4)
 F coal elevations no flame(3 out of 4)

7. 14.Repurge requirement
 MFT is reset but no firing up to 30
minutes.
15. Turbine tripped.
16. MFT trip relay cabinet power off
 or Both power off.
17. FSSS cabinet power off
 When FSSS common logic cabinet
power off.

8.  When MFT generate, system will generate alarm,
display first reason for generating the MFT signal.
Please execute furnace purging after MFT.
 MFT will cause the following action
 Close HFO and LDO oil supply main pipe valve.
 Close HFO and LDO oil return main pipe valve.
 Close all corner oil valves. HFO and LDO.
 Retract all oil gun and ignition gun.
 Trip all PAFs.
 Trip all mills.
 Trip all coal feeders.
 Close all mill inlet valve.
 Close all mill outlet valves.

9. Close SH spray water valve.
Close RH spray water valve.
MFT to local ignite control box.
MFT to ETS.
Stop electrostatic precipitator.
Stop soot blowers.
MFT to MCS.
MFT to SCS.
Reset MFT: Furnace purging command
initiated and wait till completion of purge.

10. Furnace purging is required to clean all the
obstacle in the air and coal path of boiler.
Furnace purging have many
conditions/Interlocks to execute are given
below.
1. No MFT conditions exist.
2. Any one FDF is running.
3. Any one IDF is running.
4. Both APH are running.

11. 5. Both PAFs stopped
6. The boiler total airflow > 30% and <40%.
7. Furnace press should be normal.
8. Drum level should be normal.
9. HFO and LDO oil supply main pipe valve
closed.
10. all corner oil valves closed HFO and
LDO.
11. All mills should be stopped.
12. All mill inlet(cold/hot) valve closed.
13. All mill outlet valve closed.
14. All coal feeders stopped.

12.  15. No flames are detected in the furnace.
 The furnace purging condition-2
 1. Furnace purge condition -1 should be
healthy.
 2. All auxiliary air dampers in purge position
(feedback >80%).
 The purging process is:
 When the purging condition-1 is met, push the
“start purge button”, purge command
executed.
 After the purging condition-2 is met, start the
purging process that will keep on for 5 minutes.
 When the purging process is completed after 5
minutes, reset MFT memory.

13. Furnace purging interrupt:
During this five minutes period, if any
condition happens to not exist, the furnace
purging process has to
be interrupted.

14. Permissive conditions:
1. No MFT conditions exist.
2.HFO Oil supply press normal.
3.All HFO oil valve closed.
4. HFO oil supply main pipe valve closed.
Test process:
 Step-1: Open HFO oil supply main
pipe valve, close oil return main pipe valve,
charge oil into the pipe for 60
second.

15. Monitor until HFO Oil supply press reach
the set point.
If the HFO oil supply press does not reach
the set point, charging oil fails and the
testing process has to be interrupted.
Step2:
Close HFO oil supply main pipe valve, start
to monitor oil pressure for 3 minutes.
HFO Oil supply press is not low.
If the HFO oil supply press is low, that
means the oil pipe leaks and the testing
process has to be interrupted.

16. Step3: Open HFO oil return main pipe
valve, discharging the oil from oil pipe for
10 second.
Step3: Open HFO oil return main pipe
valve, discharging the oil from oil pipe for
10 second.
Bypass test:
if necessary, operators can ignore this
testing process through pushing “bypass
button” on the console and force the oil
leak test to be success.

17. Permissive conditions:
1. No MFT conditions exist.
2.LDO Oil supply press normal.
3.All LDOO oil valve closed.
4. LDO oil supply main pipe valve closed.
Test process:
 Step-1: Open LDO oil supply main
pipe valve, close oil return main pipe valve,
charge oil into the pipe for 60
second.

18. Monitor until LDO Oil supply press reach
the set point.
If the LDO oil supply press does not reach
the set point, charging oil fails and the
testing process has to be interrupted.
Step2:
Close LDO oil supply main pipe valve, start
to monitor oil pressure for 3 minutes.
LDO Oil supply press is not low.
If the LDO oil supply press is low, that
means the oil pipe leaks and the testing
process has to be interrupted.

19. Step3: Open LDO oil return main pipe
valve, discharging the oil from oil pipe for
10 second.
Step3: Open LDO oil return main pipe
valve, discharging the oil from oil pipe for
10 second.
Bypass test:
if necessary, operators can ignore this
testing process through pushing “bypass
button” on the console and force the oil
leak test to be success.

20. Next logic in next PPT of FSSS-2
Thank You.....................