What best describes a steam boiler?

A steam boiler is best described as a closed pressure vessel that transforms water into steam. This process occurs when water is heated within the boiler, ultimately converting it to steam while maintaining a particular level of pressure. The steam produced can then be used for various applications, such as heating, power generation, or even powering engines.

This definition emphasizes the critical function of a steam boiler: not just heating water, but manipulating the pressure and heat to create steam, which is a key element in many industrial processes. By understanding this, it becomes clear how the boiler operates within larger systems, such as in power plants where steam is essential for energy production, or in heating systems that require steam for effective temperature control. This understanding differentiates steam boilers from other options that focus on heating air, storing liquids, or generating electricity directly.