What does the phenomenon known as 'swell' refer to in boiler operation?

The phenomenon known as 'swell' in boiler operation refers to a momentary rise in water level that occurs when there is an increase in steam demand. This happens because the production of steam requires a sudden influx of water to compensate for the rapid conversion of water into steam, which can cause the water level in the boiler to rise temporarily.

When steam is drawn off quickly, the boiler may react initially by allowing more water to rise due to the changes in pressure and temperature dynamics within the system. Understanding swell is crucial for operators to ensure that the boiler operates safely and efficiently, as excessive swell can lead to water carryover into the steam lines, potentially causing damage or reducing the quality of the steam produced. This concept is an important aspect of boiler operation, as it directly impacts the management of water levels and steam production.