A rotor of a modern steam turbine, used in a power plant

A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. It has almost completely replaced the reciprocating piston steam engine, invented by Thomas Newcomen and greatly improved by James Watt, primarily because of its greater thermal efficiency and higher power-to-weight ratio. Also, because the turbine generates rotary motion, rather than requiring a linkage mechanism to convert reciprocating to rotary motion, it is particularly suited for use driving an electrical generator — about 86% of all electric generation in the world is by use of steam turbines. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, as opposed to the one stage in the Watt engine, which results in a closer approach to the ideal reversible process. Image File history File linksMetadata Download high resolution version (2126x2126, 1707 KB) Steam turbine rotor produced by Siemens, Germany Photo taken from [1] with the friendly permission of Siemens Germany by Christian Kuhna, E-Mail: christian. ... Image File history File linksMetadata Download high resolution version (2126x2126, 1707 KB) Steam turbine rotor produced by Siemens, Germany Photo taken from [1] with the friendly permission of Siemens Germany by Christian Kuhna, E-Mail: christian. ... A power station (also power plant) is a facility for the generation of electric power. ... 1. ... It has been suggested that this article be split into articles entitled steam and water vapor, accessible from a disambiguation page. ... Components of a typical, four stroke cycle, DOHC piston engine. ... // The term steam engine may also refer to an entire railroad steam locomotive. ... Thomas Newcomen (baptised 24 February 1664; died 5 August 1729) was an ironmonger by trade, and a Baptist lay preacher by calling. ... James Watt James Watt (19 January 1736 – 19 August 1819) was a Scottish inventor and engineer whose improvements to the steam engine were fundamental to the changes wrought by the Industrial Revolution. ... The thermal efficiency () is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example. ... Power-to-weight ratio is a measure commonly used when comparing various vehicles (or engines), including automobiles, motorcycles and aircraft. ... “Dynamo” redirects here. ... A heat engine is a physical or theoretical device that converts thermal energy to mechanical output. ... Thermodynamic efficiency (e) is defined as: where W is the absolute value of the work done in one thermodynamic cycle. ... In thermodynamics, a reversible process (or reversible cycle if the process is cyclic) is a process that can be reversed by means of infinitesimal changes in some property of the system. ...

History

The first rudimentary steam turbine, was little more than a toy, the classic Aeolipile, created by Hero of Alexandria in 1st century Roman Egypt.^[1][2][3] Another more practicle steam turbine was invented much later in 16th century, by Taqi al-Din, who described it as a prime mover for rotating a spit.^[4] Yet, another steam turbine device was created by Italian Giovanni Branca in 1629. The modern steam turbine was invented in 1884 by English engineer, Charles A. Parsons, whose first model was connected to a dynamo that generated 7.5 kW of electricity. His patent was licensed and the turbine was scaled up shortly after by an American, George Westinghouse. The Parsons turbine turned out to be relatively easy to scale up. Within Parsons' lifetime the generating capacity of a unit was scaled by a factor of about 10,000. An illustration of Herons aeolipile An aeolipile is a device consisting of an air-tight chamber (usually a sphere or cylinder) with bent or curved pipes projecting from it, through which steam is expelled perpendicular to the radius of rotation. ... ‹ The template below (Expand) is being considered for deletion. ... The Roman Empire 120, with Aegyptus province highlighted See Egypt Province for the province of the Ottoman Empire. ... Taqi al-Din Muhammad ibn Maruf al-Shami al-Asadi (Arabic: تقي الدين محمد بن معروف الشامي السعدي) (c. ... For the philosophical/theological concept of a prime mover (that is, a self-existent being that is the ultimate cause or mover of all things), see cosmological argument. ... It has been suggested that this article or section be merged with rotisserie. ... Giovanni Branca (1571-1645) was an italian engineer and architect from Loretto who, in 1929, designed a steam turbine, which he didnt build. ... Sir Charles Algernon Parsons (June 13, 1854 – February 11, British engineer, best known for his invention of the steam turbine. ... Dynamo, or Dinamo, may refer to: Dynamo, an electrical generator Dynamo (sports society) of the Soviet Union Operation Dynamo, the 1940 mass evacuation at Dunkirk Dynamo, the rock band based in Belfast Dynamo theory, a theory relating to magnetic fields of celestial bodies Dynamo Open Air, annual heavy metal music... George Westinghouse, Jr. ...

A number of other variations of turbines were developed that worked effectively with steam. The de Laval turbine (invented by Gustaf de Laval) accelerated the steam to full speed before running it against a turbine blade. The turbine was simpler, less expensive, did not need to be pressure-proof, and could operate with any pressure of steam. Gustaf de Laval The former De Laval steam turbine factory, now converted to a conference centre, in Nacka, outside Stockholm Gustaf Patrik de Laval (May 9, 1845 - February 2, 1913) was a Swedish engineer and inventor who made important contributions to the design of steam turbines and dairy machinery. ...

Parsons turbine from the Polish destroyer ORP Wicher in Hel, Poland.

Parsons turbine from the Polish Navy destroyer ORP Wicher II Currently in the open-air naval armament exposition in Hel,Poland Picture by Topory File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Parsons turbine from the Polish Navy destroyer ORP Wicher II Currently in the open-air naval armament exposition in Hel,Poland Picture by Topory File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... ORP Wicher was a name of two destroyers of the Polish Navy: ORP Wicher commissioned in 1930 and sunk during the Polish Defence War of 1939 ORP Wicher commissioned from the Soviet Union in 1958 and scrapped in 1974 This is a disambiguation page — a navigational aid which lists... Hel (pronounce: [xÉ›l], Kashubian Hél, German Hela) is a town in Puck County, Pomeranian Voivodship, Poland, located on the tip of the Hel peninsula, some 33 kilometres from the Polish mainland. ...

Types

Steam turbines are made in a variety of sizes ranging from small 1 hp (0.75 kW) units (rare) used as mechanical drives for pumps, compressors and other shaft driven equipment, to 2,000,000 hp (1,500,000 kW) turbines used to generate electricity. There are several classifications for modern steam turbines.

Steam supply and exhaust conditions

Types of steam turbines include condensing, noncondensing, reheat, extraction and induction. Noncondensing or backpressure turbines are most widely used for process steam applications. The exhaust pressure is controlled by a regulating valve to suit the needs of the process steam pressure. These are commonly found at refineries, district heating units, pulp and paper plants, and desalination facilities where large amounts of low pressure process steam are available. A refinery is composed of a group of chemical engineering unit processes and unit operations used for refining certain materials or converting raw material into products of value. ... District heating pipe in Tübingen, Germany District heating (less commonly called teleheating) is a system for distributing heat generated in a centralized location for residential and commercial heating requirements. ... International Paper Company Wood pulp is the most common material used to make paper. ... A blank sheet of paper Paper is a commodity of thin material produced by the amalgamation of fibers, typically vegetable fibers composed of cellulose, which are subsequently held together by hydrogen bonding. ... Shevchenko BN350 desalination unit situated on the shore of the Caspian Sea. ...

Condensing turbines are most commonly found in electrical power plants. These turbines exhaust steam in a partially condensed state, typically of a quality near 90%, at a pressure well below atmospheric to a condenser. A power station (also power plant) is a facility for the generation of electric power. ... Steam quality is the amount of saturated steam that coexists with its condensate in a given system. ... Surface condenser is the commonly used term for a shell and tube heat exchanger installed on the exhaust steam from a steam turbine in thermal power stations. ...

Reheat turbines are also used almost exclusively in electrical power plants. In a reheat turbine, steam flow exits from a high pressure section of the turbine and is returned to the boiler where additional superheat is added. The steam then goes back into an intermediate pressure section of the turbine and continues its expansion. A boiler is a closed vessel in which water or other fluid is heated under pressure. ...

Extracting turbines are common in all applications. In an extracting turbine, steam is released from various stages of the turbine, and used for industrial process needs or sent to boiler feedwater heaters to improve overall cycle efficiency. Extraction flows may be controlled with a valve, or left uncontrolled.

Induction turbines introduce low pressure steam at an intermediate stage to produce additional power.

Principle of operation and design

An ideal steam turbine is considered to be an isentropic process, or constant entropy process, in which the entropy of the steam entering the turbine is equal to the entropy of the steam leaving the turbine. No steam turbine is truly isentropic, however, with typical isentropic efficiencies ranging from 20%-95% based on the application of the turbine. The interior of a turbine comprises several sets of blades, commonly referred to as buckets. One set of stationary blades is connected to the casing and one set of rotating blades is connected to the shaft. The sets intermesh with certain minimum clearances, with the size and configuration of sets varying to efficiently exploit the expansion of steam at each stage. An isentropic process (a combination of the Greek word iso -same- and entropy) is one during which the entropy of working fluid remains constant. ... Ice melting - classic example of entropy increasing[1] described in 1862 by Rudolf Clausius as an increase in the disgregation of the molecules of the body of ice. ...

Efficiency

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Schematic diagram outlining the difference between an impulse and a reaction turbine

To maximize turbine efficiency, the steam is expanded in a number of stages, generating work from each steam expansion and pressure drop. These stages are characterized by how the energy is extracted from them and are known as either impulse or reaction turbines. Most modern steam turbines are a combination of the reaction and impulse designs. Typically, higher pressure sections are impulse type and lower pressure stages are reaction type. Image File history File links Acap. ... Image File history File links Download high resolution version (572x684, 41 KB) Summary Schematic diagram summarising the differences between impulse and reaction turbines. ... Image File history File links Download high resolution version (572x684, 41 KB) Summary Schematic diagram summarising the differences between impulse and reaction turbines. ...

Impulse turbines

An impulse turbine has fixed nozzles that orient the steam flow into high speed jets. These jets contain significant kinetic energy, which the rotor blades, shaped like buckets, convert into shaft rotation as the steam jet changes direction. A pressure drop occurs in the nozzle. The pressure is the same when the steam enters the blade as it leaves the blade. As the steam flows through the nozzle, its pressure falls from steam chest pressure to condenser pressure (or atmosphere pressure). Due to this relatively higher ratio of expansion of steam in the nozzle, the steam leaves the nozzle with a very high velocity. At a specific temperature and pressure steam has certain physical properties. The certain amount of heat or thermal energy contained within the steam with an increase of temperature or pressure the contained energy also increases or vice versa. The flow of steam through a channel such as a nozzle reduces its thermal energy, however this decrease in thermal energy is equivalent to gain of kinetic energy. The thermal energy is converted from thermal to kinetic causing the steam to flow from high pressure, i.e. the steam chest, nozzle block, etc.. to an area of low pressure, i.e. the turbine casing. The steam leaving the moving blades still retains a large portion of the velocity it had after leaving the nozzle. The loss of energy due to this higher exit velocity is commonly called the "carry over velocity" or "leaving loss." In impulse turbines, steam expansion only happens at nozzles. Kaplan turbine and electrical generator cut-away view. ... The kinetic energy of an object is the extra energy which it possesses due to its motion. ... This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin in Canberra, Australia. ...

The types of impulse turbines are:

• Banki turbine
• Girard turbine
• Jonal turbine
• Pelton turbine
• Turgo turbine

Banki turbine - Wikipedia /**/ @import /w/skins-1. ... Pelton wheel from Walchensee, Germany hydro power station A Pelton wheel, also called a Pelton turbine, is one of the most efficient types of water wheel. ... Turgo turbine and generator The Turgo turbine is an impulse water turbine designed for medium head applications. ...

Reaction turbines

In a reaction turbine the rotor blades themselves are arranged to form convergent nozzles. This type of turbine makes use of the reaction force produced as the steam accelerates through the nozzles formed by the rotor. Steam is directed onto the rotor by the fixed vanes of the stator. It leaves the stator as a jet that fills the entire circumference of the rotor. The steam then changes direction and increases its speed relative to the speed of the blades. A pressure drop occurs across both the stator and the rotor, with steam accelerating through the stator and decelerating through the rotor, with no net change in steam velocity across the stage but with a decrease in both pressure and temperature, reflecting the work performed in the driving of the rotor. These types of turbines create large amounts of axial thrust, therefore, anti-friction thrust bearings are utilized. Kaplan turbine and electrical generator cut-away view. ... The stator is the fixed part of a rotating machine. ... friction is the force that opposes the relative motion or tendency toward such motion of two surfaces in contact. ... A bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement. ...

The reaction turbines are :

• Fourneyron turbine
• Francis turbine
• Thompson turbine
• Kaplan turbine
• Propeller turbine

Francis turbine (courtsey Voith-Siemens). ... A Bonneville Dam Kaplan turbine after 61 years of service The Kaplan turbine is a propeller-type water turbine that has adjustable blades. ...

Casing or shaft arrangements

These arrangements include single casing, tandem compound and cross compound turbines. Single casing units are the most basic style where a single casing and shaft are coupled to a generator. Tandem compound are used where two or more casings are directly coupled together to drive a single generator. A cross compound turbine arrangement features two or more shafts not in line driving two or more generators that often operate at different speeds. A cross compound turbine is typically used for many large applications.

Operation and maintenance

When warming up a steam turbine for use, the main steam stop valves (after the boiler) have a bypass line to allow superheated steam to slowly bypass the valve and proceed to heat up the lines in the system along with the steam turbine. Also a turning gear is engaged when there is no steam to the turbine to slowly rotate the turbine to ensure even heating to prevent uneven expansion and rotor bowing. After first rotating the turbine by the turning gear, allowing time for the rotor to assume a straight plane (no bowing), then the turning gear is disengaged and steam is admitted to the turbine. For most utility and industrial steam turbines, a starting and loading chart is included in the unit instruction manual. The starting and loading chart is used to guide turbine operators in loading their units in such a way as to minimize rotor and shell thermal stresses, but also minimize the chances of the rotor heating faster than the shell, creating a rotor long condition. When starting a shipboard steam turbine (marine unit), steam is normally admitted to the astern blades located in the LP turbine, and then to the ahead blades slowly rotating the turbine at 10 to 15 revolutions per minute (RPM) to slowly warm the turbine. Spur gears found on a piece of farm equipment A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device -- possibly another gear wheel -- so that force can be transmitted between the two devices in a...

Problems with turbines are rare and maintenance requirements are relatively small. Any imbalance of the rotor can lead to vibration, which in extreme cases can lead to a blade letting go and punching straight through the casing. Also, it is essential that the turbine be turned with dry steam. If water gets into the steam and is blasted onto the blades (moisture carryover) rapid impingement and erosion of the blades can occur, possibly leading to imbalance and catastrophic failure. Also, water entering the blades will likely result in the destruction of the thrust bearing for the turbine shaft. To prevent this, along with controls and baffles in the boilers to ensure high quality steam, condensate drains are installed in the steam piping leading to the turbine. Severe soil erosion in a wheat field near Washington State University, USA. For erosion as an operation of Mathematical morphology, see Erosion (morphology) Erosion is displacement of solids (soil, mud, rock and other particles) by the agents of ocean currents, wind, water, or ice by downward or down-slope movement...

Speed regulation

The control of a turbine with a governor is essential, as turbines need to be run up slowly to prevent damage. Some applications, such as the generation of electricity, require precise speed control. Uncontrolled acceleration of the turbine rotor can lead to an overspeed trip, which causes the nozzle valves that control the flow of steam to the turbine to close. If this fails, the turbine may continue accelerating until it breaks apart, often spectacularly. Turbines are expensive to make, requiring precision manufacture and high quality materials. A governor is a device used to measure and regulate the speed of a machine, such as an engine. ... Lightning strikes during a night-time thunderstorm. ...

Direct drive

Electrical power stations use large steam turbines driving electric generators to produce most of the world's electricity. These centralised stations include fossil fuel, nuclear, geothermal, solar thermal electric and biomass power plants. The turbines used for electric power generation are most often directly coupled to their generators. As the generators must rotate at constant synchronous speeds according to the frequency of the electric power system, the most common speeds are 3,000 revolutions per minute for 50 Hz systems, and 3,600 revolutions per minute for 60 Hz systems. Most large nuclear sets rotate at half those speeds, and have a 4-pole generator rather than the more common 2-pole one. Electricity generation is the first process in the delivery of electricity to consumers. ... Generator redirects here. ... Mohave Generating Station, a 1,580 MW coal power plant near Laughlin, Nevada A fossil fuel power plant is an energy conversion center that combusts fossil fuels to produce electricity, designed on a large scale for continuous operation. ... A nuclear power station. ... Krafla Geothermal Station in northeast Iceland Geothermal power is the use of geothermal heat to generate electricity. ... Solar thermal energy is a technology for harnessing solar power for practical applications from solar heating to electrical power generation. ... Switchgrass, a hardy plant used in the biofuel industry in the United States Rice chaff. ...

Speed reduction

The Turbinia - the first steam turbine-powered ship

Another use of steam turbines is in ships; their small size, low maintenance, light weight, and low vibration are compelling advantages. Steam turbine locomotives were also tested, but with limited success. A steam turbine is efficient only when operating in the thousands of revolutions per minute (RPM) range while application of the power in propulsion applications may be only in the hundreds of RPM, which requires that expensive and precise reduction gears be used, although several ships, such as Turbinia, had direct drive from the steam turbine to the propeller shafts. This purchase cost is offset by much lower fuel and maintenance requirements and the small size of a turbine when compared to a reciprocating engine having an equivalent power. Most modern vessels now use either gas turbines or diesel engines, however, nuclear powered vessels such as aircraft carriers and nuclear submarines use steam turbines driving the propeller shaft through a reduction gearbox as the main part of their propulsion systems. Image File history File linksMetadata Turbinia_At_Speed. ... Image File history File linksMetadata Turbinia_At_Speed. ... Turbinia was the first steam turbine powered steamship, built as an experimental vessel in 1894 and demonstrated dramatically at the Spithead Navy Review in 1897, setting the standard for the next generation of steamships. ... Italian Full rigged ship Amerigo Vespucci in New York Harbor, 1976 A ship is a large watercraft capable of offshore navigation. ... A steam turbine locomotive is a steam locomotive which transmits steam power to the wheels via a steam turbine. ... Turbinia was the first steam turbine powered steamship, built as an experimental vessel in 1894 and demonstrated dramatically at the Spithead Navy Review in 1897, setting the standard for the next generation of steamships. ... Components of a typical, four stroke cycle, DOHC piston engine. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... This article does not cite any references or sources. ... Nuclear propulsion can include a wide variety of methods, the commonality of which is the use of some form of nuclear reaction as their primary power source. ... Four aircraft carriers, (bottom-to-top) Principe de Asturias, amphibious assault carrier USS Wasp, supercarrier USS Forrestal and light V/STOL carrier HMS Invincible, showing size differences of late 20th century carriers An aircraft carrier is a warship designed to deploy and recover aircraft — in effect acting as a sea... USS Los Angeles A submarine is a specialized watercraft that can operate underwater. ...

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Steam turbine

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References

Ahmad Y. al Hassan (born 1925) Chevalier of the Legion d’Honneur: Historian of Islamic and Arabic science and technology. ... University of Aleppo (also called Aleppo University, the University freely uses both English names) is a []public university]] located in Aleppo, Syria. ...

External links

• Introduction to the steam turbine
• Photo tour of a 1,300 MW coal plant (The Zimmer Power Station, Moscow, Ohio, USA)