What is the main purpose of interlocks between drum level control and feedwater pump operation?

What is the main purpose of interlocks between drum level control and feedwater pump operation?

• A. To automatically start the feedwater pump whenever the boiler is on, ensuring high water levels.
• B. To allow the feedwater pump to run independently of drum level measurements.
• C. To ensure the pump only runs when drum level indicates a safe water level, preventing dry firing or water hammer.
• D. To minimize energy consumption by halting the pump during startup.

Answer: (C)

The main idea is to link the feedwater pump to the drum level so the pump only runs when the boiler drum shows a safe water level. This protects the boiler from two dangerous situations: dry firing, where the pump would push water into a region that isn’t actually filled, risking overheating and tube damage; and water hammer or overfill, where pumping water in when the level is already high causes pressure surges and potential damage. With proper interlocks, if the drum level drops to a low, the interlock prevents the pump from starting or stops it if it’s running, and it also prevents pumping when the level is at or above the safe range. This keeps the water level within a controlled range, promoting safe, reliable boiler operation and avoiding sudden level swings.

The main idea is to link the feedwater pump to the drum level so the pump only runs when the boiler drum shows a safe water level. This protects the boiler from two dangerous situations: dry firing, where the pump would push water into a region that isn’t actually filled, risking overheating and tube damage; and water hammer or overfill, where pumping water in when the level is already high causes pressure surges and potential damage. With proper interlocks, if the drum level drops to a low, the interlock prevents the pump from starting or stops it if it’s running, and it also prevents pumping when the level is at or above the safe range. This keeps the water level within a controlled range, promoting safe, reliable boiler operation and avoiding sudden level swings.