What happens to the steam bubbles in the drum during shrinkage?

During the phenomenon known as shrinkage in a steam drum, the pressure within the drum tends to decrease. This decrease in pressure causes the steam bubbles within the water to collapse. When the pressure drops, the vapor pressure of the steam bubbles becomes inadequate to maintain their gas form, leading to their collapse. This is a critical aspect of steam generation and heat transfer within the boiler system that can affect both efficiency and safety.

The collapse of the steam bubbles is a response to the relationship between pressure and temperature in saturated steam conditions. As the drum pressure decreases, the boiling point of the water also decreases, and the steam bubbles cannot maintain their size, leading to their collapse back into the liquid phase. Understanding this process is essential for managing boiler operations and ensuring stable conditions.