Firetube boilers are primarily used for what purpose?

Firetube boilers are primarily designed to produce steam for various applications, which often include auxiliary services on ships and in industrial settings. They operate by passing hot gases through tubes that are surrounded by water, allowing heat transfer to produce steam. While firetube boilers can indeed be used for heating, their main function in many situations is to provide steam for auxiliary components rather than for primary power generation or heating residential buildings.

In naval or marine contexts, firetube boilers typically support functions such as heating fuel oil, providing steam for auxiliary machinery, or supplying heat to various systems, making them essential for operational efficiency but not utilized for the main propulsion power generation. Their simplicity and ability to produce steam quickly make them suitable for auxiliary roles, thus justifying the chosen answer regarding their primary purpose.