For safe operation of boiler and auxiliaries even in the event of a failure of the control system, it is necessary to provide certain interlocks and trips in the control system.
Boiler trip protection
The sugar plant boiler should be provided with trip facility which will shut down the systems when it receives a trip command for the following conditions or if boiler trip push button provided in the panel is depressed.
a. FD fan trip / shut down
b. ID fan trip / shut down
c. Cogeneration turbine trip
d. Drum level low / high trip
interlocks recommended for start up of boiler auxiliaries
Some of the essential interlocks recommended for start up of boiler auxiliaries are:
a. Start ID fan when FD fan an SA fan are off.
b. Start FD fan only if ID fan is on.
c. Start SA fan only if both FD and ID fans are on
d. Start bagasse feeder only if SA fan is on
e. ID fan is of all fans shall trip.
f. Trip bagasse feeders when SA fan is tripped.
Source: Avant-Garde