In a once-through boiler, how much water is typically evaporated in the radiant evaporator?

In a once-through boiler, the radiant evaporator is designed to efficiently convert incoming water into steam. The radiant section of the boiler operates at high temperatures and pressure, allowing for a significant portion of the water to be transformed into steam as it travels through the furnace.

In this context, the typical evaporation rate in the radiant evaporator section of a once-through boiler is around 85%. This high rate is due to the direct exposure of the water to high heat radiating from the combustion of fuels, allowing for efficient heat transfer and steam generation. The design of once-through boilers maximizes steam production without the need for water accumulation, ensuring that virtually all incoming water is evaporated as it flows through this section.

The other options present various percentages that do not align with industry standards and typical operational parameters for once-through boilers. For instance, a lower percentage such as 50% or 75% suggests that more water is left unused, which contradicts the efficiency expected from such steam generation systems. A figure like 100% implies that all water is evaporated without any consideration for operational limitations, which is impractical in real-world conditions where minor variations and inefficiencies are always present. Therefore, the 85% option reflects both practical experience and technical