Why do steam flooding boilers contain 20% moisture?

Steam flooding boilers contain 20% moisture primarily to allow carry over of dissolved salts. In such systems, the presence of moisture facilitates the transport of dissolved salts and other impurities that are present in the boiler water. If these solids were to concentrate, they could lead to scaling or corrosion within the boiler system, compromising efficiency and integrity.

Maintaining a certain level of moisture helps in the overall management of water quality, enabling the system to manage impurities more effectively. This carryover is a strategy to ensure that not only does the steam maintain a quality needed for effective energy transfer, but it also helps in controlling the levels of dissolved solids in the boiler drum and associated piping. This is critical for maintaining the operational and safety standards of the boiler system.

While other options address concerns such as fuel quality, maintenance tasks, and steam efficiency, they do not accurately reflect the primary reason for maintaining 20% moisture in flooding boilers. The key objective is about managing impurities and ensuring that the boiler operates reliably over its lifespan without major integrity issues arising from salt buildup.