What is typically the maximum outlet temperature of the economizer?

The correct choice indicates that the maximum outlet temperature of the economizer is typically 10℃ below the operating temperature of the steam drum. This relationship is significant because the economizer's primary role is to preheat water before it enters the boiler and facilitate more efficient heat recovery from the flue gases.

By maintaining the economizer’s outlet temperature slightly lower than the steam drum temperature, it ensures that the water entering the boiler is at an appropriate temperature for optimal steam generation without risking overheating or unnecessary thermal stress on the boiler components. It also aids in maximizing efficiency by reducing fuel consumption while preventing thermal shock to the boiler system.

In practical applications, this temperature differential helps in managing the system's overall thermal dynamics, ensuring that the steam generation process remains efficient while preventing operational issues associated with excessively high temperatures. The target temperature allows operators to safely and effectively manage the heat exchange process within the boiler system.