In a closed feedwater heater, do steam and water mix?

In a closed feedwater heater, steam and water do not mix. The design of a closed feedwater heater allows steam to heat water indirectly without the two fluids coming into direct contact with each other. Steam is contained within a separate space, typically in a set of tubes or a shell, and transfers heat to the water circulating around it. This indirect heating is efficient for raising the temperature of the feedwater before it enters the boiler, yet it ensures that the steam and water remain distinct, which helps maintain the quality of the steam and prevents any contaminants from the water from entering the steam system.

This configuration is critical for the operational efficiency and safety of the boiler system, as it prevents potential issues related to the mixing of the two phases, such as contamination or pressure losses.