a plant designed to convert the heat from the combustion of a fuel into mechanical energy by means of steam. Mechanical energy is generally not the end product of a steam power plant but is transformed by electric generators into electric power, which is then transmitted to consumers; this type of steam power plant is called a steam electric power plant. When steam is produced in an atomic steam-generating plant, the plant is called an atomic power plant or an atomic electric power plant.
Steam power plants consist of one or a group of steam boilers and one or more steam power sources (steam engines or steam turbines) with auxiliary mechanisms, apparatus, and instruments. The simplest steam power plant is the steam power unit, which is composed of a fire-tube boiler on which a piston steam engine is mounted. High-power steam power plants consist of steam boilers and steam turbines with condensing equipment. The modern trend is to design steam power plants in boiler-turbine units (with power ratings of 300 megawatts or more) that are not interconnected for steam and water. This makes it possible to use short steam pipes with a minimum number of fittings, which is very important with high steam parameters (pressure to 24 meganewtons per sq m [240 kilograms-force per sq cm]) and temperatures of 570°C and above. Some of the steam generated in a steam power plant is often used for domestic or industrial purposes, such as heating, cooking, and drying. Steam power plants are used on riverboats and oceangoing vessels (steamships), as well as in railroad transportation (steam locomotives) and, occasionally, in steam automobiles.