NationMaster - Encyclopedia: Fossil fuel power plant

A fossil fuel power plant is an energy conversion center that burns fossil fuels to produce electricity, designed on a large scale for continuous operation. Image File history File linksMetadata Download high resolution version (2003x1474, 2150 KB) Summary This is a picture of Mohave Generating Station, a 1,580 MW coal power plant near Laughlin, Nevada. ... Image File history File linksMetadata Download high resolution version (2003x1474, 2150 KB) Summary This is a picture of Mohave Generating Station, a 1,580 MW coal power plant near Laughlin, Nevada. ... Laughlin at night, with the Colorado River in foreground Laughlin is a census-designated place (CDP) in Clark County, Nevada, United States. ... Image File history File links Portal. ... In physics and engineering, energy conversion is any process of converting energy from one form to another. ... Fossil fuels are hydrocarbons, primarily coal and petroleum (fuel oil or natural gas), formed from the fossilized remains of dead plants and animals[1] by exposure to heat and pressure in the Earths crust over hundreds of millions of years[2]. The theory that hydrocarbons were formed from these... Lightning strikes during a night-time thunderstorm. ...

Basic concepts

In a fossil fuel power plant the chemical energy stored in fossil fuels such as coal, fuel oil, natural gas or oil shale is converted successively into thermal energy, mechanical energy and, finally, electrical energy for continuous use and distribution across a wide geographic area. Almost all large fossil fuel power plants are steam-electric power plants, except for gas turbines and utility-sized reciprocating engines that may run on natural gas or diesel. Coal Coal (IPA: ) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... An oil tanker taking on bunker fuel. ... For other uses, see Natural gas (disambiguation). ... Oil shale Oil shale is a general term applied to a fine-grained sedimentary rock containing significant traces of kerogen (a solid mixture of organic chemical compounds) that have not been buried for sufficient time to produce conventional fossil fuels. ... In thermal physics, thermal energy is the energy portion of a system that increases with its temperature. ... In physics, mechanical energy describes the potential energy and kinetic energy present in the components of a mechanical system. ... Electrical energy can refer to several closely related things. ... A power station (also power plant) is a facility for the generation of electric power. ... A steam-electric power plant is a power plant in which the prime mover is steam driven. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... Components of a typical, four stroke cycle, DOHC piston engine. ... This article is about the fuel. ...

All fossil fuels generate carbon dioxide, when combusted. Chemical side reactions also take place, generating, among others, sulfur dioxide (predominantly in coal) and oxides of nitrogen. Each fossil fuel power plant is a highly complex, custom-designed system. Present construction costs, as of 2004, run to US$1,300 per kilowatt, or $650 million for a 500 MWe unit. Multiple generating units may be built at a single site for more efficient use of land, natural resources and labor. In order to meet Wikipedias quality standards, this article requires cleanup. ... Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... 2004 is a leap year starting on Thursday of the Gregorian calendar. ... ISO 4217 Code USD User(s) the United States, the British Indian Ocean Territory,[1] the British Virgin Islands, East Timor, Ecuador, El Salvador, the Marshall Islands, Micronesia, Palau, Panama, Turks and Caicos Islands, and the insular areas of the United States Inflation 2. ... The kilowatt (symbol: kW) is a unit for measuring power, equal to one thousand watts. ... The megawatt (symbol: MW) is a unit for measuring power corresponding to one million (106) watts. ... Land use is the pattern of construction and activity land is used for. ...

Image File history File links SSPX0347. ... Image File history File links SSPX0347. ...

Fuel transport and delivery

Coal is delivered by mass transport systems, truck, rail, barge or collier. A large coal train called a "unit train" may be two kilometers long, containing 100 cars with 100 tons of coal in each one, for a total load of 10,000 tons. A large plant under full load requires at least one coal delivery this size every day. Plants may get as many as three to five trains a day, especially in "peak season", during the summer months when power consumption is high. A large thermal power plant such as the one at Nanticoke Ontario stores several million tons of coal for winter use when the lakes are frozen. â€œLorryâ€ redirects here. ... This is the top-level page of WikiProject trains Rail tracks Rail transport refers to the land transport of passengers and goods along railways or railroads. ... Self propelled barge carrying bulk crushed stone A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. ... Look up collier in Wiktionary, the free dictionary. ... For other uses, see Train (disambiguation). ... Look up ton in Wiktionary, the free dictionary. ...

Modern unloaders use rotary dump devices, which eliminate problems with coal freezing in bottom dump cars. The unloader includes a train positioner arm that pulls the entire train to position each car over a coal hopper. The dumper clamps an individual car against a platform that swivels the car upside down to dump the coal. Swiveling couplers enable the entire operation to occur while the cars are still coupled together. Unloading a unit train takes about three hours.

Shorter trains may use railcars with an "air-dump", which relies on air pressure from the engine plus a "hot shoe" on each car. This "hot shoe" when it comes into contact with a "hot rail" at the unloading trestle, shoots an electric charge through the air dump apparatus and causes the doors on the bottom of the car to open, dumping the coal through the opening in the trestle. Unloading one of these trains takes anywhere from an hour to an hour and a half. Older unloaders may still use manually operated bottom-dump rail cars and a "shaker" attached to dump the coal. Generating stations adjacent to a mine may receive coal by conveyor belt or massive diesel-electric-drive trucks. This article is about industrial conveyor belts. ... A number of vehicles use a diesel-electric powerplant for providing locomotion. ...

A collier (cargo ship carrying coal) may hold 40,000 tons of coal and takes several days to unload. Some colliers carry their own conveying equipment to unload their own bunkers; others depend on equipment at the plant. Colliers are large, seaworthy, self-powered ships. For transporting coal in calmer waters, such as rivers and lakes, flat-bottomed vessels called barges are often used. Barges are usually unpowered and must be moved by tugboats or towboats. Self propelled barge carrying bulk crushed stone A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. ... A tugboat shown turning a large RORO cargo ship. ... The towboat Angelina pushes a barge in New Orleans. ...

For startup or auxiliary purposes, the plant may use fuel oil as well. Fuel oil can be delivered to plants by pipeline, tanker, tank car or truck. Oil is stored in vertical cylindrical steel tanks as large as 90,000 barrels (14,000 m³). The heavier no. 5 "bunker" and no. 6 fuels are steam-heated before pumping in cold climates. An oil tanker taking on bunker fuel. ... Commercial crude oil supertanker AbQaiq. ... A modern tank car, owned by the Union Tank Car Company, passes westbound through Rochelle Railroad Park, Rochelle, Illinois on May 29, 2005. ... Viscosity is a measure of the resistance of a fluid to deform under shear stress. ...

Plants fueled by natural gas are usually built adjacent to gas transport pipelines or have dedicated gas pipelines extended to them.

Fuel processing

Coal is prepared for use by crushing the rough coal to pieces less than 2 inches (50 mm) in size. The coal is transported from the storage yard to in-plant storage silos by rubberized conveyer belts at rates up to 4,000 tons/hour. A 400 ton silo may feed each coal pulverizer (coal mill) at a rate of up to 60 tons per hour. Coal fed into the top of the pulverizer and ground to a powder, the consistency of face powder, is blown, with air, into the furnace. A 500 MWe plant will have six such pulverizers, five of which can supply coal to the furnace at 250 tons per hour under full load. A conveyor belt or belt conveyor consists of two end pulleys, with a continuous loop of material that rotates about them. ... A pulverizer is a device for grinding coal for combustion in a furnace in a fossil fuel power plant. ...

Feedwater heating and deaeration

The feedwater used in the steam boiler is a means of transferring heat energy from the burning fuel to the mechanical energy of the spinning steam turbine. The total feedwater consists of recirculated condensed steam, referred to as condensate, from the steam turbines plus purified makeup water. Because the metallic materials it contacts are subject to corrosion at high temperatures and pressures, the makeup water is highly purified before use. A system of water softeners and ion exchange demineralizers produces water so pure that it coincidentally becomes an electrical insulator, with conductivity in the range of 0.3–1.0 microsiemens per centimeter. The makeup water in a 500 MWe plant amounts to perhaps 20 US gallons per minute (1.25 L/s) to offset the small losses from steam leaks in the system. It has been suggested that this article be split into articles entitled steam and water vapor, accessible from a disambiguation page. ... 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. ... For the hazard, see corrosive. ... A water softener reduces calcium or magnesium concentration in hard water. ... Ion exchange is defined as an exchange of ions between two electrolytes. ... This article or section is in need of attention from an expert on the subject. ... Electrical conductivity or specific conductivity is a measure of a materials ability to conduct an electric current. ...

The feedwater cycle begins with condensate water being pumped out of the condenser after travelling through the steam turbines. The condensate flow rate at full load in a 500 MWe plant is about 6,000 US gallons per minute (0.38 m³/s). 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. ...

The water flows through a series of six or seven intermediate feedwater heaters, heated up at each point with steam extracted from an appropriate duct on the turbines and gaining temperature at each stage. Typically, the condensate plus the makeup water then flows through a deaerator^[1]^[2] that removes dissolved air from the water, further purifying and reducing its corrosivity. The water may be dosed following this point with hydrazine, a chemical that removes the remaining oxygen in the water to below 5 parts per billion (ppb). It is also dosed with pH control agents such as ammonia or morpholine to keep the residual acidity low and thus non-corrosive. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A Feedwater heater is a power plant component used to pre-heat water delivered to the boiler. ... A Deaerator is a device for air removal and is used to remove dissolved gases (an alternate would be the use of water treatment chemicals) from boiler feedwater to make it non-corrosive. ... Hydrazine is the chemical compound with formula N2H4. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... The correct title of this article is . ... For other uses, see Ammonia (disambiguation). ... Morpholine is an organic chemical compound having the chemical formula C4H8NO . ... For other uses, see Acid (disambiguation). ...

Boiler operation

The boiler is a rectangular furnace about 50 ft (15 m) on a side and 130 ft (40 m) tall. Its walls are made of a web of high pressure steel tubes about 2.3 inches (60 mm) in diameter. A furnace is a device for heating air or any other fluid. ...

Pulverized coal is air-blown into the furnace from fuel nozzles at the four corners and it rapidly burns, forming a large fireball at the center. The thermal radiation of the fireball heats the water that circulates through the boiler tubes near the boiler perimeter. The water circulation rate in the boiler is three to four times the throughput and is typically driven by pumps. As the water in the boiler circulates it absorbs heat and changes into steam at 700 °F (370 °C) and 3,200 psi (22.1 MPa). It is separated from the water inside a drum at the top of the furnace. The saturated steam is introduced into superheat pendant tubes that hang in the hottest part of the combustion gases as they exit the furnace. Here the steam is superheated to 1,000 °F (540 °C) to prepare it for the turbine. Coal dust is a fine powdered form of coal. ... â€œRadiant heatâ€ redirects here. ... A boiler is a closed vessel in which water or other fluid is heated under pressure. ... The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Youngs modulus and tensile strength). ... General arrangement of a superheater installation in a steam locomotive. ...

Plants designed for lignite (brown coal) are increasingly used in locations as varied as Germany, Victoria, and North Dakota. Lignite is a much younger form of coal than black coal. It has a lower energy density than black coal and requires a much larger furnace for equivalent heat output. Such coals may contain up to 70% water and ash, yielding lower furnace temperatures and requiring larger induced-draft fans. The firing systems also differ from black coal and typically draw hot gas from the furnace-exit level and mix it with the incoming coal in fan-type mills that exhaust the pulverised coal and hot gas mixture into the boiler. Coal Coal is a fossil fuel extracted from the ground by mining. ... â€œVICâ€ redirects here. ... Official language(s) English Capital Bismarck Largest city Fargo Area Ranked 19th - Total 70,762 sq mi (183,272 kmÂ²) - Width 210 miles (340 km) - Length 340 miles (545 km) - % water 2. ...

Plants that use gas turbines to heat the water for conversion into steam use boilers known as HRSGs, Heat Recovery Steam Generators. The exhaust (waste) heat from the gas turbines is used to make superheated steam that is then used in a conventional water-steam generation cycle.

Steam turbine generator

The turbine generator consists of a series of steam turbines interconnected to each other and a generator on a common shaft. There is a high pressure turbine at one end, followed by an intermediate pressure turbine, two low pressure turbines, and the generator. As steam moves through the system and loses pressure and temperature energy it expands in volume, requiring increasing diameter and longer blades at each succeeding stage to extract the remaining energy. The entire rotating mass may be over 200 tons and 100 ft (30 m) long. It is so heavy that it must be kept turning slowly even when shut down (at 3 rpm) so that the shaft will not bow even slightly and become unbalanced. This is so important that it is one of only four functions of blackout emergency power batteries on site. They are emergency lighting, communication, station alarms and turbogenerator lube oil. 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. ... Emergency lighting The name Emergency lighting itself implies that it is required in an Emergency. ... Communication is a process that allows beings - in particular humans - to exchange information by several methods. ...

Superheated steam from the boiler is delivered through 14–16 inch (350–400 mm) diameter piping to the high pressure turbine where it falls in pressure to 600 psi (4 MPa) and to 600 °F (315 °C) through the stage. It exits via 24–26 inch (600–650 mm) diameter cold reheat lines and passes back into the boiler where the steam is reheated in special reheat pendant tubes back to 1,000 °F (540 °C). The hot reheat steam is conducted to the intermediate pressure turbine where it falls in both temperature and pressure and exits directly to the long-bladed low pressure turbines and finally exits to the condenser. For other uses, see Temperature (disambiguation). ... This article is about pressure in the physical sciences. ...

The generator, 30 ft (9 m) long and 12 ft (3.7 m) diameter, contains a stationary stator and a spinning rotor, each containing miles of heavy copper conductor—no permanent magnets here. In operation it generates up to 21,000 amps at 24,000 volts AC (504 MWe) as it spins at either 3,000 or 3,600 RPM, synchronized to the power grid. The rotor spins in a sealed chamber cooled with hydrogen gas, selected because it has the highest known heat transfer coefficient of any gas and for its low viscosity which reduces windage losses. This system requires special handling during startup, with air in the chamber first displaced by carbon dioxide before filling with hydrogen. This ensures that the highly flammable hydrogen does not mix with oxygen in the air. The stator is the fixed part of a rotating machine. ... The rotor is the non-stationary part of a rotary electric motor or alternator, which rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotors axis. ... For other uses, see Copper (disambiguation). ... For other uses, see Magnet (disambiguation). ... Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current. ... The volt is the SI derived unit for electric potential and voltage (derived from the ampere and watt). ... City lights viewed in a motion blurred exposure. ... Transmission towers Transmission lines in Lund, Sweden Electric power transmission, or more accurately Electrical energy transmission, is the second process in the delivery of electricity to consumers. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... The heat transfer coefficient is used as a fudge factor in calculating heat transfer in thermodynamics. ... Viscosity is a measure of the resistance of a fluid to deform under shear stress. ... Windage is a force created on an object by friction when there is relative movement between air and the object. ... In order to meet Wikipedias quality standards, this article requires cleanup. ... Flammable or Flammability refers to the ease at which a substance will ignite, causing fire or combustion. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...

The power grid frequency is 60 Hz across North America and 50 Hz in Europe, Oceania, Asia (Korea and parts of Japan are notable exceptions) and parts of Africa. MHZ redirects here. ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... For other uses, see Europe (disambiguation). ... For other uses, see Oceania (disambiguation). ... For other uses, see Asia (disambiguation). ... This article is about the Korean peninsula and civilization. ... A world map showing the continent of Africa Africa is the worlds second-largest and second most-populous continent, after Asia. ...

The electricity flows to a distribution yard where transformers step the voltage up to 115, 230, 500 or 765 kV AC as needed for transmission to its destination. Figure 1:Three-phase pole-mounted step-down transformer. ...

Steam condensing

The lower is the pressure of the exhaust steam leaving the low pressure turbine, the more efficient is the train of turbine stages. The exhaust steam from the low pressure turbine is condensed in a shell and tube heat exchanger commonly referred to as a surface condenser. Cooling water circulates through the tubes in the condenser's shell and the low pressure exhaust steam is condensed by flowing over the tubes as shown in the adjacent diagram. Typically the cooling water causes the steam to condense at a temperature of about 32–38 °C (90–100 °F) and that creates an absolute pressure in the condenser of about 5–7 kPa (1.5–2.0 in Hg), a vacuum of about 95 kPa (28 mmHg) relative to atmospheric pressure. The condenser, in effect, creates the low pressure required to drag steam through and increase the efficiency of the turbines. The limiting factor is the temperature of the cooling water and that, in turn, is limited by the prevailing average climatic conditions at the power plant's location. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A Shell and tube heat exchanger is a class of heat exchanger designs. ... 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. ...

From the bottom of the condenser, powerful pumps recycle the condensed steam (water) back to the feedwater heaters for reuse. The heat absorbed by the circulating cooling water in the condenser tubes must also be removed to maintain the ability of the water to cool as it circulates.

This is done by pumping the warm water from the condenser through either natural draft, forced draft or induced draft cooling towers (as seen in the image to the right) that reduce the temperature of the water by evaporation, about 11–17°C (20–30 °F) - expelling waste heat to the atmosphere. The circulation flow-rate of the cooling water in a 500 MWe unit is about 14.2 m³/s (225,000 US gal/minute) at full load.^[3] Image File history File links A_Marley_industrial_cooling_tower. ... Image File history File links A_Marley_industrial_cooling_tower. ... Image 1: Natural draft wet cooling towers at Didcot Power Station, UK Cooling towers are evaporative coolers used for cooling water or other working medium to near the ambient wet-bulb air temperature. ... Waste heat is the by-product heat of machines and technical processes for which no useful application is found. ... MWe and MWt are units for measuring the output of a power plant. ...

The condenser tubes are made of brass or stainless steel to resist corrosion from either side. Nevertheless they may become internally fouled during operation by bacteria or algae in the cooling water or by mineral scaling, all of which inhibit heat transfer and reduce thermodynamic efficiency. Many plants include an automatic cleaning system that circulates sponge rubber balls through the tubes to scrub them clean without the need to take the system off-line. For other uses, see Brass (disambiguation). ... The 630 foot high, stainless-clad (type 304L) Gateway Arch defines St. ... Thermodynamic efficiency (e) is defined as: where W is the absolute value of the work done in one thermodynamic cycle. ... A sponge rubber ball serves for tube cleaning and is used for removing fouling from the tubes of shell-and-tube heat exchangers in general and from the cooling tubes of condensers in particular. ...

Another form of condensing system is the air-cooled condenser. While these systems are similar in operation to mechanical cooling towers, they typically are more environmentally acceptable forms of condensing steam. The process is similar to that of a radiator and fan. Exhaust heat from the low pressure section of a steam turbine runs through the condensing tubes, the tubes are usually finned and ambient air is pushed through the fins with the help of a large fan. The steam condenses to water to be reused in the water-steam cycle. Radiators and convectors are types of heat exchangers designed to transfer thermal energy from one medium to another for the purpose of cooling and heating. ...

The cooling water used to condense the steam in the condenser returns to its source without having been changed other than having been warmed. If the water returns to a local water body (rather than a circulating cooling tower), it is is tempered with cool 'raw' water to prevent thermal shock when discharged into that body of water.

Diagram

Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image 1: Natural draft wet cooling towers at Didcot Power Station, UK Cooling towers are evaporative coolers used for cooling water or other working medium to near the ambient wet-bulb air temperature. ... Control valves are valves used within industrial plants and elsewhere to control operating conditions such as temperature, pressure, flow, and liquid level by fully or partially opening or closing in response to signals received from sensors that monitor changes in such conditions. ... General arrangement of a superheater installation in a steam locomotive. ... The primary use of large, industrial wet cooling towers is to lower the temperature of the cooling water used in power plants, petroleum refineries, petrochemical plants, natural gas processing plants and other industrial facilities. ... It has been suggested that this article be split into articles entitled steam and water vapor, accessible from a disambiguation page. ... Figure 1: Components of a centrifugal fan A centrifugal fan is a mechanical device for moving air or other gases. ... Three phase systems have 3 waveforms (usually carrying power) that are 2/3π radians (120 degrees,1/3 of a cycle) offset in time. ... Power line redirects here. ... A Deaerator is a device for air removal and is used to remove dissolved gases (an alternate would be the use of water treatment chemicals) from boiler feedwater to make it non-corrosive. ... Figure 1:Three-phase pole-mounted step-down transformer. ... A Feedwater heater is a power plant component used to pre-heat water delivered to the boiler. ... A combustion reaction taking place in a igniting match Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ... â€œDynamoâ€ redirects here. ... Coal Coal (IPA: ) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... Point of contact between a power transmission belt and its pulley A conveyor belt or belt conveyor consists of two end pulleys, with a continuous loop of material that rotates about them. ... It has been suggested that this article or section be merged with Economizer. ... 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. ... Coal Coal (IPA: ) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... Air preheater Airpreheater is a general term and represents any heater designed to heat air. ... A boiler feedwater pump is a specific type of pump used to pump water into a steam boiler. ... A pulverizer is a device for grinding coal for combustion in a furnace in a fossil fuel power plant. ... 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. ... This article does not adequately cite its references or sources. ... Figure 1: Components of a centrifugal fan A centrifugal fan is a mechanical device for moving air or other gases. ... 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. ... Bottom ash refers to the non combustible constituents of coal with traces of combustibles embedded in forming clinkers and sticking to hot side walls of furnace during the furnace working. ... Flue gas stack at GRES-2 Power Plant in Ekibastus, Kazakhstan is 420 meters tall[1] A flue gas stack is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. ...

Stack gas path and cleanup

As the combustion flue gas exits the boiler it is routed through a rotating flat basket of metal mesh which picks up heat and returns it to incoming fresh air as the basket rotates, This is called the air preheater. The gas exiting the boiler is laden with fly ash, which are tiny spherical ash particles. The flue gas contains nitrogen along with combustion products carbon dioxide, sulfur dioxide, and nitrogen oxides. The fly ash is removed by fabric bag filters or electrostatic precipitators. Once removed, the fly ash byproduct can sometimes be used in the manufacturing of concrete. This cleaning up of flue gases, however, only occurs in plants that are fitted with the appropriate technology. Still, the majority of coal fired power plants in the world do not have these facilties.^{[citation needed]} Legislation in Europe has been efficient to reduce flue gas pollution. Japan has been using flue gas cleaning technology for over 30 years and the US has been doing the same for over 25 years. China is now beginning to grapple with the pollution caused by coal fired power plants. The combustion product gas resulting from the burning of fossil fuels (or any other combustible fuel) is called flue gas. ... Flue gas desulfurization is technology that employs a sorbent, usually lime or limestone, to remove sulfur dioxide(SO2) from the gases produced by burning fossil fuels. ... Flue gas is gas that exits to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. ... Air preheater Airpreheater is a general term and represents any heater designed to heat air. ... Fly ash (one of several coal combustion products, or CCPs) is the finely divided mineral residue resulting from the combustion of coal in electric generating plants. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... In order to meet Wikipedias quality standards, this article requires cleanup. ... Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... The term nitrogen oxide is a general term and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2) Dinitrogen monoxide (N2O) (Nitrous oxide) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen... To meet Wikipedias quality standards, this article or section may require cleanup. ... An electrostatic precipitator (ESP), or electrostatic air cleaner is a particulate collection device that removes particles from a flowing gas (such as air) using the force of an induced electrostatic charge. ... This article is about the construction material. ...

Where required by law, the sulfur and nitrogen oxide pollutants are removed by stack gas scrubbers which use a pulverized limestone or other alkaline wet slurry to remove those pollutants from the exit stack gas. The gas travelling up the flue gas stack may by this time only have a temperature of about 50 °C (120 °F). A typical flue gas stack may be 150–180 m (500–600 ft) tall to disperse the remaining flue gas components in the atmosphere. The tallest flue gas stack in the world is 420 m (1,375 ft) tall at the GRES-2 power plant in Ekibastusz, Kazakhstan. Image File history File links PowerPlantEkibastus. ... Image File history File links PowerPlantEkibastus. ... GRES-2 Power Plant in Ekibastus, Kazakhstan. ... Many of the compounds which are dangerous to the environment can also be harmful to humans in the long-term range and come from mineral and fossil sources or are produced by humans themselves. ... Flue gas desulfurization is technology that employs a sorbent, usually lime or limestone, to remove sulfur dioxide(SO2) from the gases produced by burning fossil fuels. ... For other uses, see Limestone (disambiguation). ... The common (Arrhenius) definition of a base is a chemical compound that either donates hydroxide ions or absorbs hydrogen ions when dissolved in water. ... Flue gas stack at GRES-2 Power Plant in Ekibastus, Kazakhstan is 420 meters tall[1] A flue gas stack is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. ... GRES-2 Power Plant in Ekibastus, Kazakhstan. ... Ekibastuz is a town in Kazakhstan. ...

In the United States and a number of other countries, atmospheric dispersion modeling^[4] studies are required to determine the flue gas stack height needed to comply with the local air pollution regulations. The United State also limits the maximum height of a flue gas stack to what is known as the "Good Engineering Practice (GEP)" stack height.^[5]^[6] In the case of existing flue gas stacks that exceed the GEP stack height, any air pollution dispersion modeling studies for such stacks must use the GEP stack height rather than the actual stack height. Atmospheric dispersion modeling is performed with computer programs that use mathematical equations and algorithms to simulate how pollutants in the ambient atmosphere disperse in the atmosphere. ... Air pollution is a chemical, particulate matter, or biological agent that modifies the natural characteristics of the atmosphere. ... Good Engineering Practice or GEP is applied to engineering and technical activities to ensure that a company manufactures products of the required quality as expected by the Regulatory Authorities. ...

Supercritical steam plants

Above the critical point for water of 705 °F (374 °C) and 3,212 psia (22.1 MPa), there is no phase transition from water to steam, but only a gradual decrease in density. Boiling does not occur and it is not possible to remove impurities via steam separation. In this case a new type of design is required for plants wishing to take advantage of increased thermodynamic efficiency available at the higher temperatures. These plants, also called once-through plants because boiler water does not circulate multiple times, require additional water purification steps to ensure that any impurities picked up during the cycle will be removed. This takes the form of high pressure ion exchange units called condensate polishers between the steam condenser and the feedwater heaters. Subcritical fossil fuel power plants can achieve 36–38% efficiency. Supercritical designs have efficiencies in the low to mid 40% range, with new "ultra critical" designs using pressures of 4,400 psia (30 MPa) and dual stage reheat reaching about 48% efficiency. In physical chemistry, thermodynamics, chemistry and condensed matter physics, a critical point, also called a critical state, specifies the conditions (temperature, pressure) at which the liquid state of the matter ceases to exist. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... For other uses, see Density (disambiguation). ... Boiling, a type of phase transition, is the rapid vaporization of a liquid, which typically occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmospheric pressure. ... Thermodynamic efficiency (e) is defined as: where W is the absolute value of the work done in one thermodynamic cycle. ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ...

Nuclear power plants must operate far below the temperatures and pressures than coal fired plants do. This limits their thermodynamic efficiency to the order of 34–37%. One proposed plant design, the Supercritical_water_reactor, operates at temperatures and pressures similar to current coal plants, producing comparable efficiency. A nuclear power station. ... Supercritical water reactor scheme. ...

Gas turbine combined-cycle plants

An important class of fossil power plant uses a gas turbine, sometimes in conjunction with a steam boiler "bottoming" cycle. The efficiency of a combined cycle plant can approach 60% in large (500+ MWe) units. Such turbines are usually fueled with natural gas or diesel. While highly efficient and very quick to construct (a 1,000 MW plant may be completed in as little as two years from start of construction), the economics of such plants is heavily influenced by the volatile cost of natural gas. The combined cycle plants are designed in a variety of configurations composed of the number of gas turbines followed by the steam turbine. For example, a 3-1 combined cycle facility has three gas turbines tied to one steam turbine. The configurations range from (1-1),(2-1),(3-1),(4-1), (5-1), to (6-1). GE H Series Gas Turbine, electrical power generation This image is from: http://www. ... GE H Series Gas Turbine, electrical power generation This image is from: http://www. ... The megawatt (symbol: MW) is a unit for measuring power corresponding to one million (106) watts. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... In a combined cycle power plant, or combined cycle gas turbine (CCGT) plant, a gas turbine generator generates electricity and the waste heat from the gas turbine is used to make steam to generate additional electricity via a steam turbine, this last step enhances the efficiency of electricity generation. ... For other uses, see Natural gas (disambiguation). ... This article is about the fuel. ...

Simple-cycle gas turbine plants, without a steam cycle, are sometimes installed as emergency or peaking capacity; their thermal efficiency is much lower. The high running cost per hour is offset by the low capital cost and the intention to run such units only a few hundred hours per year. Peaking power plants (also known as Peaker Plants) are power plants that generally run only when there is a high demand, known as peak demand, for electricity. ...

Environmental impacts

Fossil fuel power contributes to acid rain, global warming, and air pollution (electricity generation is responsible for 38 percent of USA carbon dioxide emissions).^[7] Acid rain is caused by the emission of nitrogen oxides and sulfur dioxide into the air. These themselves may be only mildly acidic, yet when it reacts with the atmosphere, it creates acidic compounds such as Carbolic acid, nitric acid and sulfuric acid that fall as rain, hence the term acid rain. In Europe and the USA, stricter emission laws have reduced the environmental hazards associated with this problem. The term acid rain or more accurately acid precipitation is commonly used to mean the deposition of acidic components in rain, snow, dew, or dry particles. ... Global mean surface temperatures 1850 to 2006 Mean surface temperature anomalies during the period 1995 to 2004 with respect to the average temperatures from 1940 to 1980 Global warming is the observed increase in the average temperature of the Earths atmosphere and oceans in recent decades and the projected... Air pollution is a chemical, particulate matter, or biological agent that modifies the natural characteristics of the atmosphere. ... Phenol or carbolic acid is a white crystalline solid, with a chemical formula of C6H5OH, a melting point of 43 C, and a boiling point of 182 C at the pressure of 1 atmosphere (or 101080 Pa). ... The chemical compound nitric acid (HNO3), also known as aqua fortis and spirit of nitre, is an aqueous solution of hydrogen nitrate (anhydrous nitric acid). ... Sulfuric (or sulphuric) acid, H2SO4, is a strong mineral acid. ...

Another danger related to coal combustion is the emission of fly ash, tiny solid particles that are dangerous for public health. (Natural gas plants emit virtually no fly ash) These can be filtered out of the stack gas, although this does not happen everywhere. The most modern plants that burn coal use a different process, in which synthesis gas is made out of a reaction between coal and water. This is purified of most pollutants and then used initially to power gas turbines, then the residual heat is used for a steam turbine. The pollution levels of such plants are drastically lower than those of "classical" coal power plants. However, all coal burning power plants emit carbon dioxide. Research has shown that increased concentration of carbon dioxide in the atmosphere is positively correlated with a rise in mean global temperature, also known as climate change. Syngas (from synthesis gas) is the name given to gasses of varying composition that are generated in coal gasification and some types of waste-to-energy facilities. ... In order to meet Wikipedias quality standards, this article requires cleanup. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 450,000 years For current global climate change, see Global warming. ...

Coal also contains low levels of uranium, thorium, and other naturally-occurring radioactive isotopes whose release into the environment leads to radioactive contamination. While these substances are present as very small trace impurities, enough coal is burned that significant amounts of these substances are released. A 1,000 MW coal-burning power plant could release as much as 5.2 tons/year of uranium (containing 74 pounds of uranium-235) and 12.8 tons/year of thorium. The radioactive emission from this coal power plant is 100 times greater than a comparable nuclear power plant with the same electrical output; including processing output, the coal power plant's radiation output is over 3 times greater.^[8]. General Name, symbol, number uranium, U, 92 Chemical series actinides Group, period, block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight 232. ... A radionuclide is an atom with an unstable nucleus. ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ...

Trace amounts of mercury can exist in coal and other fossil fuels.^[9] When these fuels burn, mercury vapor can be released and the mercury is a neurotoxic heavy metal which bioaccumulates in food chains and is especially harmful to aquatic ecosystems. According to the United States Department of Energy, the worldwide emission of mercury from both natural and human sources was 5,500 tons in 1995.^[9] and coal-fired plants in the USA release an estimated 48 tons annually, which is less than 1 percent of the worldwide emissions.^[9] The Environmental Working Group (a privately funded environmental advocacy organzation) alleges that coal-fired power plants are the largest emitters of mercury in the USA.^[10] The United States Department of Energy (DOE) is a Cabinet-level department of the United States government responsible for energy policy and nuclear safety. ...

Alternatives to fossil fuel power plants include solar power and other renewable energies (see non-carbon economy). Solar power describes a number of methods of harnessing energy from the light of the sun. ... Renewable energy flows involve natural phenomena such as sunlight, wind, tides and geothermal heat. ... A low-carbon economy is an economy in which carbon dioxide emissions from the use of carbon based fuels (coal, oil and gas) are significantly reduced. ...

Clean coal

Recent developments in the application of fossil fuels include the utilisation of clean coal. Here carbon dioxide produced from the combustion process can be stored in geological formations. This is particularly applicable to empty oil and gas deposits. A number of these carbon sequestration schemes are being planned, most notably for the North Sea. Clean coal is the name attributed to coal chemically washed of minerals and impurities, sometimes gasified, burned and the resulting flue gases treated with steam and reburned so as to make the carbon dioxide in the flue gas economically recoverable. ... Carbon sequestration from a fossil-fuel power station A carbon dioxide sink or CO2 sink is a carbon reservoir that is increasing in size, and is the opposite of a carbon source. The main sinks are the oceans and growing vegetation. ... The North Sea is a sea of the Atlantic Ocean, located between the coasts of Norway and Denmark in the east, the coast of the British Isles in the west, and the German, Dutch, Belgian and French coasts in the south. ...

Contents

Basic concepts

Fuel transport and delivery

Fuel processing

Feedwater heating and deaeration

Boiler operation

Steam turbine generator

Steam condensing

Diagram

Stack gas path and cleanup

Supercritical steam plants

Gas turbine combined-cycle plants

Environmental impacts

Clean coal

See also

References

Bibliography

External links

Contents

Basic concepts var ACE_AR = {Site: '756743', Size: '300250'};

Fuel transport and delivery

Fuel processing

Feedwater heating and deaeration

Boiler operation

Steam turbine generator

Steam condensing

Diagram

Stack gas path and cleanup

Supercritical steam plants

Gas turbine combined-cycle plants

Environmental impacts

Clean coal

See also

References

Bibliography

External links

Basic concepts