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Introduction:

Al Hussein electricity station is one of the best in Jordan, it had beenestablished in 1973, it works with steam turbine engine side by side with agas turbine, and nowadays its capacity can be approximated to be 396 megawatts.

The station had been established at 4 stages; the gas ones had a capacity of14.5 mega watts & the steam ones with capacity of 33 mega watts.

At the first stage; they established 2 gas units and two steam units

Second stage; established another steam unit; each one has capacity of 33mega watts.

Stage three: at the third stage they had established 3 more steam units; thecapacity of each is 66 mega watts.

Stage four: there they established one more steam unit with capacity of 66mega watts.

Al Aqaba station: it generates about 42% of the requirement of Jordan, itcontains of 5 steam station each one has 130 mega watts capacity, it usessea water for cooling, and also they used the natural gas to generateelectricity for the environment;

Also there are many other stations like: Marka station, el kerba el samraetc.

There are also some experiments to use the wind energy to generateelectricity like: el Ebrahimiye station in Irbid and another one in Tafilah, aswell as another one which is still under construction in Jerash, also there aremany projects which are under discussion to see how useful they will be likeWadi Araba station and Hofa, Fojeejetc.

Also for the dams, in Jordan there are 9 dams with capacity of 220 m3. Theyuse these dams to generate electricity as well. But it is still on limited way.

For the solar energy, there are good ways to use it specially for heating thewater in houses, but also they are many experiments to use it, especially forlighting the roads in the kingdom, it will be a useful power because:

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1- Geographic place (radiation power, temperature, wind velocity).2- Technology used.3- Performance of the components.

Nowadays, there is also going to use the nuclear energy for generating

electricity, it is still at the beginning but the studies said that it will be aneconomic way for electricity.

Electric Energy:

It is a kind of energy which is available in the natural. We can get itfrom nature as shocks or friction, but it is not effect or economic. So theyused other ways to get it like chemical reaction in the batteries or from the

mechanical motion to electrical energy by using copper wire

To generate electricity we can divide the ways into two types depending onwhether it consumes fuel or not as:

1- Fuel consumes ways, like steam station and hydraulic stations.2- Non fuel stations, like solar systems and wind energy stations.

Electric power stations:

In the stations they generates electricity as a huge amount of energy, itcan be thousands of mega watts.

Mostly the stations located near the fuel resources, where the convert theelectrical potential by electrical transformers to high voltage (33 KV- 400KV), to make it ready for being transferred from the station to itsconsuming points. For transferring this energy they need big towerswhere we put at the top of the tower the electrical wires where thecurrent will pass through. Then they deliver the energy at low voltage(110-220 V) using a large transformers.

Electrostatic Generator:

An electrostatic generator, or electrostatic machine, is a mechanical device that produces staticelectricity, or electricity at high voltage and low continuous current. The knowledge of staticelectricity dates back to the earliest civilizations, but for millennia it remained merely aninteresting and mystifyingphenomenon, without a theory to explain its behavior and oftenconfused with magnetism. By the end of the 17th Century, researchers had developed practical

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means of generating electricity by friction, but the development of electrostatic machines did notbegin in earnest until the 18th century, when they became fundamental instruments in the studiesabout the new science ofelectricity. Electrostatic generators operate by using manual (or other)power to transform mechanical workinto electric energy. They develop electrostatic charges ofopposite signs rendered to two conductors, using only electric forces. They work by usingmoving plates, drums, or belts to carry electric charge to a high potential electrode. The charge isgenerated by one of two methods: either the turboelectric effect (friction) orelectrostaticinduction.

Types of Power Stations:

1- Steam Power Stations: (energy converter)

This kind uses different types of fuel, depends on what isavailable like coal or liquid fuel as well as the natural andindustrial gas.

It is big stations; low cost for it is great performance, as well as itcan be used to desalination; which make it as a double usestations.

Site Selection of Steam Power Station:

1- To be near to the fuel resources.2- The condenser needs much amount of water. So it is

required that the station must be near the cooling waterresource. So most of the time it is located near beaches or atthe river sides.

3- To be near consuming points. For saving the cost of makingtransferring system.

How does it work?

It depends on the available fuel type, and burning it in thecombustion chambers; then to use the heat energy to heat thewater inside the boilers, then to change its states to gas state at aspecified temperature and pressure, then to deliver this steam to

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the steam turbines which already designed for this purpose, sothe fast steam revolves the turbine with fast speed, so the heatenergy converts to mechanical energy on the pivot of the turbine,by direct connection between the turbine pivot and the electrical

motor(alternator), when the pivot revolves it is deliver the motionto the electrical motor pivot which convert this energy toelectricity by using the magnetic property (rotor) and the fixedpart from the generator ( stator), so the electricity generates onthe side of the stator

Components of steam station:

1- Furnace: big vessel used to burn the fuel, it had various

shapes depending on the fuel type, and it is connected tostoring unites and transferring, trading and exhaustingsystems.

2- Boiler: Big vessel contains pure water, which is heated byburning the fuel which transfers it to steam. Most of the timethe furnace and the boiler are located on the same place toensure the direct contact between them. the boiler sizesvaries depending on the

a- Station size.b- Steam amount per time unit.1- Turbine: it is solid turbine, it had a cylindrical pivot which

contains concaved plates, when the steam clash with theplates, it makes it to revolve, which effect the pivot torevolve with speed of 3000 rpm, turbines varies in size andshape depending on the steam speed, steam size and steampressure, as well as its temperature; also the size of the

station.2- Generator: it is electrical device, contains two parts, onemoved (rotor) and another fixed (stator), the rotor directconnected to the turbine pivot. And the two parts arecovered with a copper wire to take the magnetic field fromthe rotor and deliver it to stator as electricity current.

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3- Condenser: big solid vessel. The steam enters from the topside of the condenser after it loses much of its pressure andtemperature, and from the bottom flow a water current, anddue to the heat transfers between them the steam back to

be pure water and resent to the boilers again.4- Chimney: long cylindrical chimney built from bricks, it is

used to exhaust the exhausted gases to a high height tomake a less pollution.

5- Auxiliaries: a large numbers from mechanical and electricaldevices and speed controllers which helps to complete thework.

1- Nuclear Power Station:It can be considered as heating station, because it works onthe same principle; which is generating electricity fromsteam.But the difference is instead of the furnace, here we have anuclear reactor where we get the heat as a result of anuclear reaction, then this huge energy transferred to the

steam in the boilers, then to the turbines and then to thegenerators.

2- Hydraulic Power Stations:

It is using the moving water (rivers and lakes) which arenearly high where we can think of fallen water to generateenergy. So they building dams at these places and also thestations there, also they can make waterfall or natural one todirect generation of electricity.

The principle here is to use the potential energy of water whichgained by position and transfer it to electricity.

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Components of Hydro-Electric Station:

1- Penstock: one or more pipes located at the bottom of thedam or at the top of the waterfalls and connected to the

turbines, there are valves at the first and at the end of thepipe for controlling purposes.2- Turbines: turbine and generators located in vertical order,

generator up and turbine down; so when the gate in thepenstock opened, the water flows inside the pipes with highspeed; which rotates the turbine, so the rotor in thegenerators moved which make the electricity current at thesides of the stator.

3- Draught tubes: special tube to bull the flow water outsidethe turbine.

4- Auxiliaries: extra but important devices which use tocomplete the work like: pumps, gates, valves, speedcorrectors.

4-Tidal Power Stations:

The tidal flow is a natural event, which causes an increase in sealevel due to moon gravity. When the moon is in the nearest pointthe water rises, and when the moon in the far point it isdecreases.

The best place where this type is used is in the north coast ofFrance where the tidal has a height of 30m. So the turbinesdistributed in such away it fits the tidal flow. The station in France

has a capacity of 400 mega watts.

5-Internal Combustion Engines:

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It is a station uses the liquid fuel, where it burns in the chambersafter been mixing with the air, so the result is a high pressuregases which can move the pistons in the diesel case or theturbines in gas turbines.

Diesel power station:

It is fast turn on/off machines. But it consumes high amount offuel, so the cost depends on the fuel cost, from other side thecapacity for this kind the capacity is low (3 MW), it is easy to setup. And it is been used in the emergency states. In this case theyuse many engines from this type to get the required energy.

6-Gas turbine:It has varies capacities (1-250 MW). Its turn on/off period is (2-10minutes); they are cheap, simple, fast set up ability, and easymaintenance, also it doesnt need too much water for cooling. Itcan use many types of fuels (rough petrol, neutral gas, industrialgas ).

But it has disadvantages like: it has short age, the output is not as

much required (15-25 %); also consumes too much fuel to steamstations.

Components of the station:

1- Air compressor: compressing the atmospheric air to highpressures.

2- Combustion chamber: mixing air with fuel and then burningto give high pressure and temperature.

3- Turbine: horizontal pivot turbine, from one side connected toair compressor and from the other side to the generator, butby a gear box to decrease the speed because the turbinerotates at high speed that the generator cannot operate atit.

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4- Generator: nowadays there are two turbines in the cycle,one for the pressure and speed, and the other oneconnected to the generator called the power turbine.

5- Auxiliaries:

a- Air filtersb- Start engine mostly diesel or electrical motor.c- Burn helping devices.d- Barometer and thermometer.e- Electrical measurement devices.

7-Wind power station:

Big fans places somewhere we can get a high speed wind, the

fans rotates which gave us a mechanical energy that we canconvert it to electricity.

8-Solar station:

Nowadays it is used to heat the water in the houses, and to lightthe roads, but the researchers are looking to generate a largeamount of electricity from this type using the solar cells, and theydid many projects about this where the most famous one was the

solar car when they designed it with a maximum speed of60km/h.

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Turbine:A turbine is a rotary engine that extracts energy from a fluid or air flow and

converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is ashaft or drum, with blades attached. Moving fluid acts on the blades, or theblades react to the flow, so that they move and impart rotational energy tothe rotor. Early turbine examples are windmills and water wheels.

Gas, steam, and water turbines usually have a casing around the blades thatcontains and controls the working fluid. Credit for invention of the steamturbine is given both to the British Engineer Sir Charles Parsons (1854-1931),for invention of the reaction turbine and to Swedish Engineer Gustav deLaval (1845-1913), for invention of the impulse turbine. Modern steamturbines frequently employ both reaction and impulse in the same unit,typically varying the degree of reaction and impulse from the blade root toits periphery.

A device similar to a turbine but operating in reverse, i.e. driven, is acompressor or pump. The axial compressor in many gas turbine engines is acommon example. Here again, both reaction and impulse are employed andagain, in modern axial compressors, the degree of reaction and impulse willtypically vary from the blade root to its periphery.

Claude Burdin coined the term from the Latinturbo, or vortex, during an1828 engineering competition. Benoit Fourneyron, a student of ClaudeBurdin, built the first practical water turbine.

Theory of operation

A working fluid contains potential energy (pressure head) and kinetic energy(velocity head). The fluid may be compressible or incompressible. Severalphysical principles are employed by turbines to collect this energy: turbine isgay

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Impulse turbinesThese turbines change the direction of flow of a high velocity fluid orgas jet. The resulting impulse spins the turbine and leaves the fluidflow with diminished kinetic energy. There is no pressure change of thefluid or gas in the turbine rotor blades (the moving blades), as in the

case of a steam or gas turbine; the entire pressure drop takes place inthe stationary blades (the nozzles).

Before reaching the turbine, the fluid'spressure headis changed to velocityheadby accelerating the fluid with a nozzle. Pelton wheels and de Lavalturbines use this process exclusively. Impulse turbines do not require apressure casement around the rotor since the fluid jet is created by thenozzle prior to reaching the blading on the rotor. Newton's second lawdescribes the transfer of energy for impulse turbines.

Reaction turbinesThese turbines develop torque by reacting to the gas or fluid's

pressure or mass. The pressure of the gas or fluid changes as it passesthrough the turbine rotor blades. A pressure casement is needed tocontain the working fluid as it acts on the turbine stage(s) or theturbine must be fully immersed in the fluid flow (such as with windturbines). The casing contains and directs the working fluid and, forwater turbines, maintains the suction imparted by the draft tube.Francis turbines and most steam turbines use this concept. Forcompressible working fluids, multiple turbine stages are usually usedto harness the expanding gas efficiently. Newton's third law describesthe transfer of energy for reaction turbines.

t In the case of steam turbines, such as would be used for marine

applications or for land-based electricity generation, a Parsons type reactionturbine would requireapproximately double the numberof blade rows as a de Laval typeimpulse turbine, for the samedegree of heat drop. Whilst thismakes the Parsons turbine muchlonger and heavier, the overallefficiency of a reaction turbine isslightly higher than the equivalentimpulse turbine for the same heat

drop.Steam turbines and later, gasturbines developed continuallyduring the 20th Century, continueto do so and in practice, modernturbine designs will use bothreaction and impulse concepts to

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varying degrees whenever possible. Wind turbines use an airfoil to generatelift from the moving fluid and impart it to the rotor (this is a form of reaction).Wind turbines also gain some energy from the impulse of the wind, bydeflecting it at an angle. Cross flow turbines are designed as an impulsemachine, with a nozzle, but in low head applications maintain some

efficiency through reaction, like a traditional water wheel. Turbines withmultiple stages may utilize either reaction or impulse blading at highpressure. Steam Turbines were traditionally more impulse but continue tomove towards reaction designs similar to those used in Gas Turbines. At lowpressure the operating fluid medium expands in volume for small reductionsin pressure. Under these conditions (termed Low Pressure Turbines) bladingbecomes strictly a reaction type design with the base of the blade solelyimpulse. The reason is due to the effect of the rotation speed for each blade.As the volume increases, the blade height increases, and the base of theblade spins at a slower speed relative to the tip. This change in speed forcesa designer to change from impulse at the base, to a high reaction style tip.

Classical turbine design methods were developed in the mid 19th century.Vector analysis related the fluid flow with turbine shape and rotation.Graphical calculation methods were used at first. Formulae for the basicdimensions of turbine parts are well documented and a highly efficientmachine can be reliably designed for any fluid flow condition. Some of thecalculations are empirical or 'rule of thumb' formulae and others are basedon classical mechanics. As with most engineering calculations, simplifyingassumptions were made.

Velocity triangles can be used to calculate the basic performance of aturbine stage. Gas exits the stationary turbine nozzle guide vanes at

absolute velocity Va1. The rotor rotates at velocity U. Relative to the rotor;the velocity of the gas as it impinges on the rotor entrance is Vr1. The gas isturned by the rotor and exits, relative to the rotor, at velocity Vr2. However,in absolute terms the rotor exit velocity is Va2. The velocity triangles areconstructed using these various velocity vectors. Velocity triangles can beconstructed at any section through the blading (for example: hub , tip,midsection and so on) but are usually shown at the mean stage radius. Meanperformance for the stage can be calculated from the velocity triangles, atthis radius, using the Euler equation:

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Whence:

Modern turbine design carries thecalculations further. Computational fluiddynamics dispenses with many of thesimplifying assumptions used to deriveclassical formulas and computer softwarefacilitates optimization. These tools haveled to steady improvements in turbinedesign over the last forty years.

The primary numerical classification of aturbine is its specific speed. This numberdescribes the speed of the turbine at itsmaximum efficiency with respect to thepower and flow rate. The specific speed isderived to be independent of turbine size.Given the fluid flow conditions and thedesired shaft output speed, the specificspeed can be calculated and anappropriate turbine design selected.

The specific speed, along with somefundamental formulas can be used toreliably scale an existing design of known performance to a new size with

corresponding performance.Off-design performance is normally displayed as a turbine map orcharacteristic.

Types of turbines Steam turbines are used for the generation of electricity in thermal

power plants, such as plants using coal or fuel oil or nuclear power.They were once used to directly drive mechanical devices such asships' propellers (e.g. theTurbinia), but most such applications nowuse reduction gears or an intermediate electrical step, where theturbine is used to generate electricity, which then powers an electric

motor connected to the mechanical load. Turbo electric ship machinerywas particularly popular in the period immediately before and duringWWII, primarily due to a lack of sufficient gear-cutting facilities in USand UK shipyards.

Gas turbines are sometimes referred to as turbine engines. Suchengines usually feature an inlet, fan, compressor, combustor andnozzle (possibly other assemblies) in addition to one or more turbines.

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Transonic turbine. The gas flow in most turbines employed in gasturbine engines remains subsonic throughout the expansion process. Ina transonic turbine the gas flow becomes supersonic as it exits thenozzle guide vanes, although the downstream velocities normallybecome subsonic. Transonic turbines operate at a higher pressure ratio

than normal but are usually less efficient and uncommon. This turbineworks well in creating power from water.

Contra-rotating turbines. With axial turbines, some efficiencyadvantage can be obtained if a downstream turbine rotates in theopposite direction to an upstream unit. However, the complication canbe counter-productive. A contra-rotating steam turbine, usually knownas the Ljungstrm turbine, was originally invented by Swedish EngineerFredrik Ljungstrm (1875-1964), in Stockholm and in partnership withhis brother Birger Ljungstrm he obtained a patent in 1894. The designis essentially a multi-stage radial turbine (or pair of 'nested' turbinerotors) and met with some success, particularly in marine applications,

where its compact size and low weight lent itself well to turbo-electricapplications. In this radial arrangement, the overall efficiency istypically less than that of Parsons or de Laval turbines.

Statorless turbine. Multi-stage turbines have a set of static (meaningstationary) inlet guide vanes that direct the gas flow onto the rotatingrotor blades. In a statorless turbine the gas flow exiting an upstreamrotor impinges onto a downstream rotor without an intermediate set ofstator vanes (that rearrange the pressure/velocity energy levels of theflow) being encountered.

Ceramic turbine. Conventional high-pressure turbine blades (and

vanes) are made from nickel based alloys and often utilize intricateinternal air-cooling passages to prevent the metal from overheating. Inrecent years, experimental ceramic blades have been manufacturedand tested in gas turbines, with a view to increasing Rotor InletTemperatures and/or, possibly, eliminating air-cooling. Ceramic bladesare more brittle than their metallic counterparts, and carry a greaterrisk of catastrophic blade failure. This has tended to limit their use injet engines and gas turbines, to the stator (stationary) blades.

Shroudedturbine. Many turbine rotor blades have shrouding at thetop, which interlocks with that of adjacent blades, to increase dampingand thereby reduce blade flutter. In large land-based electricitygeneration steam turbines, the shrouding is often complemented,especially in the long blades of a low-pressure turbine, with lacingwires. These are wires which pass through holes drilled in the blades atsuitable distances from the blade root and the wires are usually brazedto the blades at the point where they pass through. The lacing wiresare designed to reduce blade flutter in the central part of the blades.

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The introduction of lacing wires substantially reduces the instances ofblade failure in large or low-pressure turbines.

Shroud less turbine. Modern practice is, wherever possible, toeliminate the rotor shrouding, thus reducing the centrifugal load on theblade and the cooling requirements.

Bladeless turbine uses the boundary layer effect and not a fluidimpinging upon the blades as in a conventional turbine.

Water turbines

Pelton turbine, a type of impulse water turbine.

Francis turbine, a type of widely used water turbine.

Kaplan turbine, a variation of the Francis Turbine.

Voith, water turbine.

Wind turbine.These normally operate as a single stage withoutnozzle and interstage guide vanes. An exception is the olienne Bolle,which has a stator and a rotor, thus being a true turbine.

Other

Velocity compound "Curtis". Curtis combined the de Laval and ParsonsTurbine by using a set of fixed nozzles on the first stage or stator andthen a rank of fixed and rotating blade rows, as in the Parsons or deLaval, typically up to ten compared with up to a hundred stages of aParsons design. The overall efficiency of a Curtis design is less than

that of either the Parsons or de Laval designs, but it can besatisfactorily operated through a much wider range of speeds,including successful operation at low speeds and at lower pressures,which made it ideal for use in ships' power plant. In a Curtisarrangement, the entire heat drop in the steam takes place in theinitial nozzle row and both the subsequent moving blade rows andstationary blade rows merely change the direction of the steam. Itshould be noted that the use of a small section of a Curtisarrangement, typically one nozzle section and two or three rows ofmoving blades is usually termed a Curtis 'Wheel' and in this form, theCurtis found widespread use at sea as a 'governing stage' on many

reaction and impulse turbines and turbine sets. This practice is stillcommonplace today in marine steam plant.

Pressure Compound Multistage Impulse or Rateau. The Rateauemploys simple Impulse rotors separated by a nozzle diaphragm. Thediaphragm is essentially a partition wall in the turbine with a series oftunnels cut into it, funnel shaped with the broad end facing the

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previous stage and the narrow the next they are also angled to directthe steam jets onto the impulse rotor.

Uses of turbines:

Almost all electrical power on Earth is produced with a turbine of some type.Very high efficiency steam turbines harness about 40% of the thermalenergy, with the rest exhausted as waste heat.

Mostjet engines rely on turbines to supply mechanical work from theirworking fluid and fuel as do all nuclear ships and power plants.

Turbines are often part of a larger machine. A gas turbine, for example, mayrefer to an internal combustion machine that contains a turbine, ducts,compressor, combustor, heat-exchanger, fan and (in the case of onedesigned to produce electricity) an alternator. However, it must be notedthat the collective machine referred to as the turbine in these cases isdesigned to transfer energy from a fuel to the fluid passing through such aninternal combustion device as a means of propulsion, and not to transfer

energy from the fluid passing through the turbine to the turbine as is thecase in turbines used for electricity provision etc.

Reciprocating piston engines such as aircraft engines can use a turbinepowered by their exhaust to drive an intake-air compressor, a configurationknown as a turbocharger (turbine supercharger) or, colloquially, a "turbo".

Turbines can have very high power density (i.e. the ratio of power to weight,or power to volume). This is because of their ability to operate at very highspeeds. The Space Shuttle's main engines use turbo pumps (machinesconsisting of a pump driven by a turbine engine) to feed the propellants(liquid oxygen and liquid hydrogen) into the engine's combustion chamber.

The liquid hydrogen turbo pump is slightly larger than an automobile engine(weighing approximately 700 lb) and produces nearly 70,000 hp (52.2 MW).

Turbo expanders are widely used as sources of refrigeration in industrialprocesses.

Turbines could also be used as powering system for a remote controlledplane that creates thrust and lifts the plane of the ground. They come indifferent sizes and could be as small as soda can, still be strong enough tomove objects with a weight of 100kg.

Shrouded tidal turbines:

An emerging renewable energy technology is the shrouded tidal turbine enclosed ina venture shaped shroud or duct producing a sub atmosphere of low pressurebehind the turbine. It is often claimed that this allows the turbine to operate athigher efficiency (than the Betz limit of 59.3%) because the turbine can typicallyproduce 3 times more power than a turbine of the same size in free stream. This,however, is something of a misconception because the area presented to the flow isthat of the largest duct cross-section. If this area is used for the calculation, it willbe seen that the turbine still cannot exceed the Betz limit. Further, due to frictional

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losses in the duct, it is unlikely that the turbine will be able to produce as muchpower as a free-stream turbine with the same radius as the duct.

Although situating the rotor in the throat of the duct allows the blades to besupported at their tips (thus reducing bending stress from hydrodynamic thrust) thefinancial impact of the large amount of steel in the duct must not be omitted from

any energy cost calculations.As shown in the CFD generated figure, it can beseen that a downstream low pressure (shown bythe gradient lines) draws upstream flow into theinlet of the shroud from well outside the inlet ofthe shroud. This flow is drawn into the shroud andconcentrated (as seen by the red colored zone).This augmentation of flow velocity corresponds toa 3-4 times increase in energy available to theturbine. Therefore a turbine located in the throatof the shroud is then able to achieve higherefficiency, and an output 3-4 times the energy the

turbine would be capable of if it were in open orfree stream. However, as mentioned above, it isnot correct to conclude that this circumvents theBetz limit. The figure shows only the near-fieldflow, which is accelerated through the duct. A far-field image would show a more complete picture ofhow the free-stream flow is affected by the obstruction.

Considerable commercial interest has been shown in recent times in shrouded tidalturbines as it allows a smaller turbine to be used at sites where large turbines arerestricted. Arrayed across a seaway or in fast flowing rivers shrouded tidal turbinesare easily cabled to a terrestrial base and connected to a grid or remotecommunity. Alternatively the property of the shroud that produces an acceleratedflow velocity across the turbine allows tidal flows formerly too slow for commercialuse to be utilized for commercial energy production.

While the shroud may not be practical in wind, as a tidal turbine it is gaining morepopularity and commercial use. A non-symmetrical shrouded tidal turbine (the typediscussed above) is mono directional and constantly needs to face upstream inorder to operate. It can be floated under a pontoon on a swing mooring, fixed to theseabed on a mono pile and yawed like a wind sock to continually face upstream. Ashroud can also be built into a tidal fence increasing the performance of theturbines. Several companies (for example, Lunar Energy) are proposing bi-directional ducts that would not be required to turn to face the oncoming tide everysix hours.

Cabled to the mainland they can be grid connected or can be scaled down toprovide energy to remote communities where large civil infrastructures arenot viable. Similarly to tidal stream open turbines they have little if anyenvironmental or visual amenity impact.

The Boiler:

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A boiler is a closed vessel in whichwateror otherfluid is heated. The heated or vaporized fluidexits the boiler for use in various processes or heating application.

Materials:

Thepressure vessel in a boiler is usually made ofsteel (or alloy steel), or historically ofwrought

iron. Stainless steel is virtually prohibited (by the ASME Boiler Code) for use in wetted parts ofmodern boilers, but is used often in superheating sections that will not be exposed to liquid boilerwater. In live steam models, copperorbrass is often used because it is more easily fabricated insmaller size boilers. Historically, copper was often used forfireboxes (particularly forsteamlocomotives), because of its better formability and higherthermal conductivity; however, in more recent times, the highprice of copper often makes this an uneconomic choice andcheaper substitutes (such as steel) are used instead.

For much of the Victorian "age of steam", the only materialused for boiler making was the highest grade of wrought iron,with assembly by riveting. This iron was often obtained fromspecialist ironworks, such as at Creator Moor(UK), noted forthe high quality of theirrolled plate and its suitability for high-reliability use in critical applications, such as high-pressureboilers. In the 20th century, design practice instead movedtowards the use of steel, which is stronger and cheaper, withwelded construction, which is quicker and requires less labor.

Cast iron may be used for the heating vessel of domestic waterheaters. Although such heaters are usually termed "boilers",their purpose is usually to produce hot water, not steam, andso they run at low pressure and try to avoid actual boiling. Thebrittleness of cast iron makes it impractical for high pressuresteam boilers.

Fuel:

The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, ornatural gas.Electric steam boilers use resistance- orimmersion-type heating elements. Nuclearfission is also used as a heat source for generating steam. Heat recovery steam generators(HRSGs) use the heat rejected from other processes such as gas turbines.

Configurations:

Boilers can be classified into the following configurations:

"Pot boiler"or"Haycock boiler": a primitive "kettle" where a fire heats a partially-filledwater container from below. 18th Century Haycock boilers generally produced and storedlarge volumes of very low-pressure steam, often hardly above that of the atmosphere.These could burn wood or most often, coal. Efficiency was very low.

Fire-tube boiler. Here, water partially fills a boiler barrel with a small volume left aboveto accommodate the steam (steam space). This is the type of boiler used in nearly allsteam locomotives. The heat source is inside a furnace orfirebox that has to be keptpermanently surrounded by the water in order to maintain the temperature of the heatingsurface just belowboiling point. The furnace can be situated at one end of a fire-tube

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which lengthens the path of the hot gases, thus augmenting the heating surface which canbe further increased by making the gases reverse direction through a second parallel tubeor a bundle of multiple tubes (two-pass or return flue boiler); alternatively the gases maybe taken along the sides and then beneath the boiler through flues (3-pass boiler). In thecase of a locomotive-type boiler, a boiler barrel extends from the firebox and the hotgases pass through a bundle of fire tubes inside the barrel which greatly increase theheating surface compared to a single tube and further improve heat transfer. Fire-tubeboilers usually have a comparatively low rate of steam production, but high steam storagecapacity. Fire-tube boilers mostly burn solid fuels, but are readily adaptable to those ofthe liquid or gas variety.

Water-tube boiler. In this type, the water tubes are arranged inside a furnace in a numberof possible configurations: often the water tubes connect large drums, the lower onescontaining water and the upper ones, steam and water; in other cases, such as a monotube boiler, water is circulated by a pump through a succession of coils. This typegenerally gives high steam production rates, but less storage capacity than the above.Water tube boilers can be designed to exploit any heat source and are generally preferredin high pressure applications since the high pressure water/steam is contained withinsmall diameter pipes which can withstand the pressure with a thinner wall.

Flash boiler. A specialized type of water-tube boiler.

Fire-tube boiler with Water-tube firebox. Sometimes the two above types have beencombined in the following manner: the firebox contains an assembly of water tubes,called thermic siphons. The gases then pass through a conventional fire tube boiler.Water-tube fireboxes were installed in many Hungarian locomotives, but have met withlittle success in other countries.

Sectional boiler. In a cast iron sectional boiler, sometimes called a "pork chop boiler" thewater is contained inside cast iron sections. These sections are assembled on site to createthe finished boiler.

Safety:

Historically, boilers were a source of many serious injuries and property destruction due topoorly understood engineering principles. Thin and brittle metal shells can rupture, while poorlywelded or riveted seams could open up, leading to a violent eruption of the pressurized steam.Collapsed or dislodged boiler tubes could also spray scalding-hot steam and smoke out of the airintake and firing chute, injuring the firemen who loaded coal into the fire chamber. Extremelylarge boilers providing hundreds of horsepower to operate factories could demolish entirebuildings.

A boiler that has a loss of feed water and is permitted to boil dry can be extremely dangerous. Iffeed water is then sent into the empty boiler, the small cascade of incoming water instantly boils

on contact with the superheated metal shell and leads to a violent explosion that cannot becontrolled even by safety steam valves. Draining of the boiler could also occur if a leak occurredin the steam supply lines that were larger than the make-up water supply could replace. TheHartford Loop was invented in 1919 by the Hartford Steam Boiler and Insurance Company as amethod to help prevent this condition from occurring, and thereby reduce their insurance claims.

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Superheated steam boilers:

Most boilers heat water until it boils, and thenthe steam is used at saturation temperature

(i.e., saturated steam). Superheated steamboilers boil the water and then further heat thesteam in a superheated. This provides steam atmuch higher temperature, but can decrease theoverall thermal efficiency of the steamgeneratingplant due to the fact that the highersteam temperature requires a higher flue gasexhaust temperature. There are several ways tocircumvent this problem, typically byproviding a feed water heating "economizer", and/or a combustion air heater in the hot flue gasexhaust path. There are advantages to superheated steam and this may (and usually will) increaseoverall efficiency of both steam generation and its utilization considered together: gains in input

temperature to a turbine should outweigh any cost in additional boiler complication and expense.There may also be practical limitations in using "wet" steam, as causing condensation dropletswill damage turbine blades.

Superheated steam presents unique safety concerns because, if there is a leak in the steam piping,steam at such high pressure/temperature can cause serious, instantaneous harm to anyoneentering its flow. Since the escaping steam will initially be completely superheated vapor, it isnot easy to see the leak, although the intense heat and sound from such a leak clearly indicates itspresence.

The superheated works like coils on an air conditioning unit, however to a different end. Thesteam piping (with steam flowing through it) is directed through the flue gas path in the boilerfurnace. This area typically is between 1,300 C (2,372 F)-1,600 C (2,912 F). Some super

heaters are radiant type (absorb heat by radiation), others are convection type (absorb heat via afluid i.e. gas) and some are a combination of the two. So whether by convection or radiation theextreme heat in the boiler furnace/flue gas path will also heat the superheated steam piping andthe steam within as well. It is important to note that while the temperature of the steam in thesuperheated is raised, the pressure of the steam is not: the turbine or moving pistons offer a"continuously expanding space" and the pressure remains the same as that of the boiler. Theprocess of superheating steam is most importantly designed to remove all droplets entrained inthe steam to prevent damage to the turbine blading and/or associated piping.

Supercritical steam generators:

Supercritical steam generators (also known as Bensonboilers) are frequently used for the

production of electric power. They operate at "supercritical pressure". In contrast to a "subcriticalboiler", a supercritical steam generator operates at such a high pressure (over3,200 psi/22.06 MPa 3,200 psi/220.6 bar that actual boiling ceases to occur, and the boiler has nowater - steam separation. There is no generation of steam bubbles within the water, because thepressure is above the "critical pressure" at which steam bubbles can form. It passes below thecritical point as it does work in the high pressure turbine and enters the generator's condenser.This is more efficient, resulting in slightly less fuel use. The term "boiler" should not be used fora supercritical pressure steam generator, as no "boiling" actually occurs in this device.

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History of supercritical steam generation:

Contemporary supercritical steam generators are sometimes referred as Benson boilers. In 1922,Mark Benson was granted a patent for a boiler designed to convert water into steam at highpressure.

Safety was the main concern behind Bensons concept. Earlier steam generators were designedfor relatively low pressures of up to about 100 bar, corresponding to the state of the art in steamturbine development at the time. One of their distinguishing technical characteristics was theriveted drum. These drums were used to separate water and steam, and were often the source ofboiler explosions, usually with catastrophic consequences. However, the drum can be completelyeliminated if the evaporation process is avoided altogether. This happens when water is heated ata pressure above the critical pressure and then expanded to dry steam at subcritical pressure. Athrottle valve located downstream of the evaporator can be used for this purpose.

As development of Benson technology continued, boiler design soon moved away from theoriginal concept introduced by Mark Benson. In 1929, a test boiler that had been built in 1927began operating in the thermal power plant at Gartenfeld in Berlin for the first time in subcriticalmode with a fully open throttle valve. The second Benson boiler began operation in 1930 withouta pressurizing valve at pressures between 40 and 180 bar at the Berlin cable factory. Thisapplication represented the birth of the modern variable-pressure Benson boiler. After thatdevelopment, the original patent was no longer used. The Benson boiler name, however, wasretained.

Two current innovations have a good chance of winning acceptance in the competitive marketfor once-through steam generators:

A new type of heat-recovery steam generator based on the Benson boiler, which hasoperated successfully at the Cottam combined-cycle power plant in the central part ofEngland,

The vertical tubing in the combustion chamber walls of coal-fired steam generators which

combines the operating advantages of the Benson system with the design advantages ofthe drum-type boiler. Construction of a first reference plant, the Yaomeng power plant inChina, commenced in 2001.

Hydronic boilers:

Hydronic boilers are used in generating heat for residential and industrial purposes. They are thetypical power plant forcentral heating systems fitted to houses in northern Europe (where theyare commonly combined with domestic water heating), as opposed to the forced-airfurnaces orwood burning stoves more common inNorth America. The hydronic boiler operates by way ofheating water/fluid to a preset temperature (or sometimes in the case ofsingle pipe systems, untilit boils and turns to steam) and circulating that fluid throughout the home typically by way of

radiators, baseboard heaters or through the floors. The fluid can be heated by any means...gas,wood, fuel oil, etc, but in built-up areas where piped gas is available, natural gas is currently themost economical and therefore the usual choice. The fluid is in an enclosed system andcirculated throughout by means of a motorized pump. The name can be a misnomer in that,except for systems using steam radiators, the water in a properly functioning hydronic boilernever actually boils. Most new systems are fitted with condensing boilers for greater efficiency.These boilers are referred to as condensing boilers because they condense the water vapor in theflue gases to capture the latent heat of vaporization of the water produced during combustion.

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Hydronic systems are being used more and more in new construction in North America forseveral reasons. Among the reasons are:

They are more efficient and more economical than forced-airsystems (although initialinstallation can be more expensive, because of the cost of the copper and aluminum).

The baseboard copper pipes and aluminum fins take up less room and use less metal than the

bulky steel ductwork required for forced-air systems.

They provide more even, less fluctuating temperatures than forced-air systems. The copperbaseboard pipes hold and release heat over a longer period of time than air does, so thefurnace does not have to switch off and on as much. (Copper heats mostly throughconduction and radiation, whereas forced-air heats mostly through forced convection. Air hasmuch lowerthermal conductivity and higherspecific heat than copper; however, convectionresults in faster heat loss of air compared to copper. See also thermal mass.)

They do not dry out the interior air as much.

They do not introduce any dust, allergens, mold, or (in the case of a faulty heat exchanger)combustion byproducts into the living space.

Forced-air heating does have some advantages, however. See forced-air heating.

Accessories:

Boiler fittings and accessories

Safety valve: It is used to relieve pressure and prevent possible explosion of a boiler.

Water level indicators: They show the operator the level of fluid in the boiler, alsoknown as a sight glass, water gauge or water column is provided.

Bottom blow down valves: They provide a means for removing solid particulates thatcondense and lay on the bottom of a boiler. As the name implies, this valve is usuallylocated directly on the bottom of the boiler, and is occasionally opened to use the

pressure in the boiler to push these particulates out.

Continuous blow down valve: This allows a small quantity of water to escapecontinuously. Its purpose is to prevent the water in the boiler becoming saturated withdissolved salts. Saturation would lead to foaming and cause water droplets to be carriedover with the steam - a condition known as priming.

Flash Tank: High pressure blow down enters this vessel where the steam can 'flash'safely and be used in a low-pressure system or be vented to atmosphere while theambient pressure blows down flows to drain.

Automatic Blow down/Continuous Heat Recovery System: This system allows theboiler to blow down only when makeup water is flowing to the boiler, thereby

transferring the maximum amount of heat possible from the blow down to the makeupwater. No flash tank is generally needed as the blow down discharged is close to thetemperature of the makeup water.

Hand holes: They are steel plates installed in openings in "header" to allow forinspections & installation of tubes and inspection of internal surfaces.

Steam drum internals, a series of screen, scrubber & cans (cyclone separators).

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Low- water cutoff: It is a mechanical means (usually a float switch) that is used to turnoff the burner or shut off fuel to the boiler to prevent it from running once the water goesbelow a certain point. If a boiler is "dry-fired" (burned without water in it) it can causerupture or catastrophic failure.

Surface blow down line: It provides a means for removing foam or other lightweight

non-condensable substances that tend to float on top of the water inside the boiler. Circulating pump: It is designed to circulate water back to the boiler after it has

expelled some of its heat.

Feed water check valve or clack valve: A non-return stop valve in the feed waterline.This may be fitted to the side of the boiler, just below the water level, or to the top of theboiler.

Top feed: A check valve (clack valve) in the feed waterline, mounted on top of theboiler. It is intended to reduce the nuisance oflime scale. It does not prevent lime scaleformation but causes the lime scale to be precipitated in a powdery form which is easilywashed out of the boiler.

Desuperheater tubes or bundles: A series of tubes or bundles of tubes in the waterdrum or the steam drum designed to cool superheated steam. Thus is to supply auxiliaryequipment that doesn't need, or may be damaged by, dry steam.

Chemical injection line: A connection to add chemicals for controlling feed waterpHs

Steam accessories

Main steam stop valve:

Steam traps:

Main steam stop/Check valve: It is used on multiple boiler installations.

Combustion accessories

Fuel oil system:

Gas system:

Coal system:

Other essential items

Pressure gauges:

Feed pumps:

Fusible plug:

Inspectors test pressure gauge attachment:

Name plate: Registration plate:

Controlling draft:

Most boilers now depend on mechanical draft equipment rather than natural draft. This isbecause natural draft is subject to outside air conditions and temperature of flue gases leaving thefurnace, as well as the chimney height. All these factors make proper draft hard to attain andtherefore make mechanical draft equipment much more economical.

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There are three types of mechanical draft:

Induced draft: This is obtained one of three ways, the first being the "stack effect" of aheated chimney, in which the flue gas is less dense than the ambient air surrounding theboiler. The denser column of ambient air forces combustion air into and through theboiler. The second method is through use of a steam jet. The steam jet oriented in the

direction of flue gas flow induces flue gasses into the stack and allows for a greater fluegas velocity increasing the overall draft in the furnace. This method was common onsteam driven locomotives which could not have tall chimneys. The third method is bysimply using an induced draft fan (ID fan) which removes flue gases from the furnaceand forces the exhaust gas up the stack. Almost all induced draft furnaces operate with aslightly negative pressure.

Forced draft: Draft is obtained by forcing air into the furnace by means of a fan (FD fan)and ductwork. Air is often passed through an air heater; which, as the name suggests,heats the air going into the furnace in order to increase the overall efficiency of the boiler.Dampers are used to control the quantity of air admitted to the furnace. Forced draftfurnaces usually have a positive pressure.

Balanced draft: Balanced draft is obtained through use of both induced and forced draft.This is more common with larger boilers where the flue gases have to travel a longdistance through many boiler passes. The induced draft fan works in conjunction with theforced draft fan allowing the furnace pressure to be maintained slightly belowatmospheric.

Condenser:In systems involving heat transfer, a condenser is a device or unit used to condense a substancefrom its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given upby the substance, and will transfer to the condenser coolant. Condensers are typically heatexchangers which have various designs and come in many sizes ranging from rather small (hand-

held) to very large industrial-scale units used in plant processes. For example, a refrigeratorusesa condenser to get rid ofheat extracted from the interior of the unit to the outside air. Condensersare used in air conditioning, industrial chemical processes such as distillation, steampowerplants and other heat-exchange systems. Use of cooling water or surrounding air as the coolant iscommon in many condensers.

Example types of condensers:

A surface condenseris an example of such a heat-exchange system. It is a shell and tubeheat exchangerinstalled at the outlet of every steam turbine in thermal power plants.Commonly, the cooling waterflows through the tube side and the steam enters the shellside where the condensation occurs on the outside of the heat transfer tubes. Thecondensate drips down and collects at the bottom, often in a built-in pan called a hotwell.The shell side often operates at a vacuum or partial vacuum, often produced by attachedairejectors.

In chemistry, a condenser is the apparatus which cools hot vapors, causing them tocondense into a liquid. See "Condenser (laboratory)" forlaboratory-scale condensers, asopposed to industrial-scale condensers. Examples include the Liebig condenser,Grahamcondenser, and Allihn condenser. This is not to be confused with a condensation reaction

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which links two fragments into a single molecule by an addition reaction and anelimination reaction.

In laboratory distillation, reflux, and rotary evaporators, several types of condensers arecommonly used. The Liebig condenser is simply a straight tube within a cooling waterjacket, and is the simplest (and relatively least expensive) form of condenser. The

Graham condenser is a spiral tube within a water jacket, and the Allihn condenser has aseries of large and small constrictions on the inside tube, each increasing the surface areaupon which the vapor constituents may condense. Being more complex shapes tomanufacture, these latter types are also more expensive to purchase. These three types ofcondensers are laboratory glassware items since they are typically made of glass.Commercially available condensers usually are fitted with ground glass joints and comein standard lengths of 100, 200, and 400 mm. Air-cooled condensers are unjacketed,while water-cooled condensers contain a jacket for the water.

Larger condensers are also used in industrial-scale distillationprocesses to cool distilledvaporinto liquid distillate. Commonly, the coolant flows through the tube side anddistilled vapor through the shell side with distillate collecting at or flowing out the

bottom. A condenser unit used in central air conditioning systems typically has a heat exchanger

section to cool down and condense incoming refrigerant vapor into liquid, a compressorto raise the pressure of the refrigerant and move it along, and a fan for blowing outside airthrough the heat exchanger section to cool the refrigerant inside. A typical configurationof such a condenser unit is as follows: The heat exchanger section wraps around the sidesof the unit with the compressor inside. In this heat exchanger section, the refrigerant goesthrough multiple tube passes, which are surrounded by heat transfer fins through whichcooling air can move from outside to inside the unit. There is a motorized fan inside thecondenser unit near the top, which is covered by some grating to keep any objects fromaccidentally falling inside on the fan. The fan is used to blow the outside cooling air in

through the heat exchange section at the sides and out the top through the grating. Thesecondenser units are located on the outside of the building they are trying to cool, withtubing between the unit and building, one for vapor refrigerant entering and another forliquid refrigerant leaving the unit. Of course, an electric powersupply is needed for thecompressor and fan inside the unit.

Direct contact condenser

In this type of condenser, vapors are poured into the liquid directly. The vapors lose theirlatent heat of vaporization; hence, vapors transfer their heat into liquid and the liquidbecomes hot. In this type of condensation, the vapor and liquid are of same type ofsubstance.

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Figure1: waterturbine whichwill be used inFrance.

Figure 2: A plan showinghow turbine and

generatorconnected.

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Figure 3: Condenser.

Figure 4: Gas Turbine.

Figure 5: Water turbine.

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Figure 6: Nuclear plant.

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Figure 7: Steam Power Plant

Figure 8: thermal power plant plane.

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Figure 9: Wind Power Station.

Figure 10:Wind FanPlane.

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Figure 11: Inside a hydraulic power plant.

Figure 12:Hydraulic

PowerStation.