A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force is transformed, by a connecting rod and flywheel, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine.
Pressurized water reactors (PWRs) constitute the large majority of the world's nuclear power plants and are one of three types of light water reactor (LWR), the other types being boiling water reactors (BWRs) and supercritical water reactors (SCWRs). In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator. In contrast to a boiling water reactor, pressure in the primary coolant loop prevents the water from boiling within the reactor. All LWRs use ordinary water as both coolant and neutron moderator.
A high pressure watertube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes. In smaller boilers, additional generating tubes are separate in the furnace, while larger utility boilers rely on the water-filled tubes that make up the walls of the furnace to generate steam.
A steam explosion is an explosion caused by violent boiling or flashing of water into steam, occurring when water is either superheated, rapidly heated by fine hot debris produced within it, or heated by the interaction of molten metals. Pressure vessels, such as pressurized water (nuclear) reactors, that operate above atmospheric pressure can also provide the conditions for a steam explosion. The water changes from a liquid to a gas with extreme speed, increasing dramatically in volume. A steam explosion sprays steam and boiling-hot water and the hot medium that heated it in all directions, creating a danger of scalding and burning.
A heat recovery steam generator (HRSG) is an energy recovery heat exchanger that recovers heat from a hot gas stream. It produces steam that can be used in a process (cogeneration) or used to drive a steam turbine.
A thermal power station is a power station in which heat energy is converted to electric power. In most of the places in the world the turbine is steam-driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle. The greatest variation in the design of thermal power stations is due to the different heat sources; fossil fuel dominates here, although nuclear heat energy and solar heat energy are also used. Some prefer to use the term energy center because such facilities convert forms of heat energy into electrical energy. Certain thermal power stations are also designed to produce heat energy for industrial purposes, or district heating, or desalination of water, in addition to generating electrical power.
A deaerator is a device that removes oxygen and other dissolved gases from water, such as feedwater for steam-generating boilers. Dissolved oxygen in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment and forming oxides (rust). Dissolved carbon dioxide combines with water to form carbonic acid that causes further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 ppb by weight (0.005 cm³/L) or less, as well as essentially eliminating carbon dioxide.
The steam-electric power station is a power station in which the electric generator is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser. The greatest variation in the design of steam-electric power plants is due to the different fuel sources.
A steam generator is a type of boiler used to produce steam for climate control and potable water heating in railroad passenger cars. The output of a railroad steam generator is low pressure, saturated steam that is passed through a system of pipes and conduits throughout the length of the train.
Economizers, or economisers (UK), are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid. The term economizer is used for other purposes as well. Boiler, power plant, heating, Refrigeration, ventilating, and air conditioning (HVAC) uses are discussed in this article. In simple terms, an economizer is a heat exchanger.
A boiler or steam generator is a device used to create steam by applying heat energy to water. Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure but, at pressures above this, it is more usual to speak of a steam generator.
Steam is water in the gas phase, which is formed when water boils or evaporates. Steam is invisible; however, "steam" often refers to wet steam, the visible mist or aerosol of water droplets formed as this water vapour condenses. At lower pressures, such as in the upper atmosphere or at the top of high mountains, water boils at a lower temperature than the nominal 100 °C (212 °F) at standard pressure. If heated further it becomes superheated steam.
Yarrow boilers are an important class of high-pressure water-tube boilers. They were developed by Yarrow & Co. (London), Shipbuilders and Engineers and were widely used on ships, particularly warships.
Boilers for generating steam or hot water have been designed in countless shapes, sizes and configurations. An extensive terminology has evolved to describe their common features. This glossary provides definitions for these terms.
A high-pressure steam locomotive is a steam locomotive with a boiler that operates at pressures well above what would be considered normal. In the later years of steam, boiler pressures were typically 200 to 250 psi. High-pressure locomotives can be considered to start at 350 psi (2.41 MPa), when special construction techniques become necessary, but some had boilers that operated at over 1,500 psi (10.34 MPa).
A steam generator is a form of low water-content boiler, similar to a flash steam boiler. The usual construction is as a spiral coil of water-tube, arranged as a single, or monotube, coil. Circulation is once-through and pumped under pressure, as a forced-circulation boiler. The narrow-tube construction, without any large-diameter drums or tanks, means that they are safe from the effects of explosion, even if worked at high pressures. The pump flowrate is adjustable, according to the quantity of steam required at that time. The burner output is throttled to maintain a constant working temperature. The burner output required varies according to the quantity of water being evaporated: this can be either adjusted by open-loop control according to the pump throughput, or by a closed-loop control to maintain the measured temperature.
A forced circulation boiler is a boiler where a pump is used to circulate water inside the boiler. This differs from a natural circulation boiler which relies on current density to circulate water inside the boiler. In some forced circulation boilers, the water is circulated twenty times the rate of evaporation.
