What are the various interlocks used in Boilers??

 

1.What do you mean by Interlocks?

 Interlocks are the programmed or hardwired control system made to protect the machine or system from damages or disturbances

Interlocks and protections involve sensors, cables, wires, local push buttons, logics, timers, probes etc.

 2.What is the significance of interlocks?

 Significance of interlocks;

• To protect the system against damages/disturbance
• To protect the equipment
• To avoid damages to the man and machine
• To avoid operation disturbances

 3.What are the various protections used in Boilers?

• High drum level trip
• Low drum level trip
• High main steam pressure trip
• High positive draught trip
• High negative draught trip
• High main steam temperature trip

 4.What are the various interlocks provided for Boiler feed pumps?

 Boiler feed pumps trip on acting following interlocks

• Low de-aerator level
• High bearing vibration
• High bearing temperature
• High feed water temperature at suction
• High drum level

 5.Write a brief note on Boiler interlocks

 Read Generator and Turbine inter tripping

Sl No.	Interlock	Significance
1	High drum level-FD fans trip followed by fuel feeding system & ID fans	To avoid carryover of water particles in steam To avoid thermal shock to super heater coils
2	Low drum level-FD fans trip followed by fuel feeding system & ID fans	To avoid over heating of pressure parts due to lack of water
3	FD fans trip-Fuel feeding system trip	To avoid jamming of fuel feeding system & grate
4	High furnace draught-FD & SA fans trip	To avoid furnace explosion
5	Low furnace draught-ID fans trip	To avoid explosion of ESP & related ducts to vacuum pressure
6	High main steam pressure-Boiler trips (FD & fuel feeding system)	To avoid failure of pressure parts due to high steam pressure
7	High main steam temperature-Boiler trips (FD & fuel feeding system)	To avoid failure of pressure parts due to high steam temperature
8	PA fan trips- Fuel feeding system trips	To avoid jamming of fuel feeding system
9	High main steam pressure-Start up vent CV auto open	To avoid failure of pressure parts due to high steam pressure

 

For more details, read >>>

Power plant and calculations

Read Practical approach to power plant O&M

Practical Approach to Power Plant Operation and Maintenance