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محطات الطاقة الحرارية (Thermal Power Plants)

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    الصورة الرمزية د.محمد باشراحيل
    د.محمد باشراحيل
    د.محمد باشراحيل غير متواجد حالياً

    إستشاري الملتقى

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    محطات الطاقة الحرارية (Thermal Power Plants)

    محطات الطاقة الحرارية ( (Thermal Power Plant


    السلام عليكم ورحمة الله ،،
    قام أحد الأخوة في أحد المواضيع بشرح مبسط مختصر عن المحطات البخارية ، فجزاه الله خيرا ، وقد سبق وان أرفقت كتابا شاملا موسعا لمحطات التوليد سواء البخارية(Steam Power Plant) منها او الغازية (Gas Turbine Power Plant) اوالمركبة (Combined Cycle Power Plant) وهذا الكتاب هو (Power Generation Handbook) والذي يشمل ( وانا لا أحب الإعادة والترجمة لما هو مكتوب وموجود أصلا باللغة الإنجليزية إلا انني وجدت نفسي مضطرا للإيضاح) :

    Chapter 1: Review of Thermodynamics Principlesمراجعة لأساسيات علم الحراريات
    Chapter 2: Steam Power Plantsمحطات الطاقة الحرارية
    Chapter 3: Steam Turbines and Auxiliariesالتربينات البخارية وملحقاتها
    Chapter 4: Turbines Governing System انظمة حواكم التربينات
    Chapter 5: Steam Chests and Valves اوعية البخار والصمامات
    Chapter 6: Turbine Protection Devices أجهزة الحماية للتربينات
    Chapter 7: Turbine Instrumentation القياسات للتربينات
    Chapter 8: Lubrication Systems أنظمة التشحيم والتزييت
    Chapter 9: Gland Sealing Systems انظمة السدادت
    Chapter 10: An Overview of Gas Turbines مراجعة للترينات الغازية
    Chapter 11: Gas Turbines Compressors ضواغط التربينات الغازية
    Chapter 12: Gas Turbines Combustors مشعلات التربينات الغازية
    Chapter 13: Axial Flow Turbines تربينات التدفق المحوري
    Chapter 14: Gas Turbines Materials مواد التربينات الغازية

    Chapter 15: Gas Turbines Lubrication and Fuel System انظمة وقود وتشحيم التربينات الغازية

    Chapter 16: Gas Turbines Bearing and Seals رولمانات وسدادات التربينات الغازية
    Chapter 17: Gas Turbines Instrumentation and Control Systems أنظمة القياس والتحكم
    Chapter 18: Gas Turbines Performance Characteristics خصائص الأداءللتربينات الغازية
    Chapter 19: Gas Turbines Operating and Maintenance Considerations إعتبارات التشغيل والصيانة
    Chapter 20: Gas Turbines Emission Guidelines and Control Methods توجيهات العادم وطرق التحكم
    Chapter 21: Combined Cycles الدورات المختلطة (المركبة)
    Chapter 22: Selection Consideration of Combined Cycles and Cogeneration Plants إعتبارات الإختيار للمحطات المختلطة والتوليد المزدوج
    Chapter 23: Applications of Cogeneration and Combined-Cycles Plants تطبيقات للمحطات المختلطة والتوليد المزدوج
    Chapter 24: Cogeneration Application Considerations اعتبارات التطبيق للمزدوجة
    Chapter 25: Economic and Technical Consideration for Combined-Cycle Performance—Enhancement Options ألإعتبارات الإقتصادية والفنية للمحطات المزدوجة
    Chapter 26: Fundamentals of Electric Systems أساسيات الأنظمة الكهربية
    Chapter 27: Introduction to Machinery Principles مقدمة لأساسيات الماكينات
    Chapter 28: Transformers المحولات
    Chapter 29: Transformers Components and Maintenance مكونات المحولات والصيانة
    Chapter 30: Ac Machine Fundamentals اساسيات ماكينات التيار المتردد
    Chapter 31: Synchronous Generators مولدات التوافق
    Chapter 32: Generator Components, Auxiliaries, and Excitation مكونات المولد وملحقاته
    Chapter 33: Generators Testing, Inspection, and Maintenanceالفحص والإختبار والصيانة للمولدات


    إلا ان هناك موضوعا عن الغلايات (المراجل البخارية) اورده المهندس عبدالناصر عجوة ،على ما أذكر، قدم فيه شرحا جيدا عنها. ارجو المعذرة من الأخوة المهندسين والفت النظر الكريم إلى ضرورة الرجوع ومتابعة المواضيع المطروحة قبل إعداد اي موضوع جديد ومن ثم إثراء الموضوع القديم وتقديم فكرة أبداعية جديدة تساهم في التقدم . مع الشكر.

    وهذا هو رابط الكتاب (Power Generation Handbook)
    http://www.arab-eng.org/vb/t125544.html

    *************************
    واحب ان انقل موضوع من خلال موسوعة الويكيبيديا Wikipedia لسهولته وبساطة تناوله لمحطة التوليد وليكون في متناول الأخوة المهندسين وكا يتضح فالموضوع يشمل على عدة عناوين مترابطة .
    مع دعائي للجميع بالتوفيق.

    ************************

    Thermal power station

    From Wikipedia, the free encyclopedia


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    A thermal power station near Sofia, Bulgaria



    Mohave Generating Station, a 1,580 MW thermal power station near Laughlin, Nevada fuelled by coal



    Geothermal power station in Iceland


    A thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which either drives an electrical generator or does some other work, like ship propulsion. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle. The greatest variation in the design of thermal power stations is due to the different fuel sources. Some prefer to use the term energy center because such facilities convert forms of heat energy into electrical energy.
    *******s

    [hide]

    [edit] General

    Almost all coal, nuclear, geothermal, solar thermal electric, and waste incineration plants, as well as many natural gas power plants are thermal. Natural gas is frequently combusted in gas turbines as well as boilers. The waste heat from a gas turbine can be used to raise steam, in a combined cycle plant that improves overall efficiency. Power plants burning coal, oil, or natural gas are often referred to collectively as fossil-fuel power plants. Some biomass-fueled thermal power plants have appeared also. Non-nuclear thermal power plants, particularly fossil-fueled plants, which do not use cogeneration are sometimes referred to as conventional power plants.
    Commercial electric utility power stations are most usually constructed on a very large scale and designed for continuous operation. Electric power plants typically use three-phase or individual-phase electrical generators to produce alternating current (AC) electric power at a frequency of 50 Hz or 60 Hz (Hertz, which is an AC sine wave per second) depending on its location in the world. Other large companies or institutions may have their own usually smaller power plants to supply heating or electricity to their facilities, especially if heat or steam is created anyway for other purposes. Shipboard steam-driven power plants have been used in various large ships in the past, but these days are used most often in large naval ships. Such shipboard power plants are general lower power capacity than full-size electric company plants, but otherwise have many similarities except that typically the main steam turbines mechanically turn the propulsion propellers, either through reduction gears or directly by the same shaft. The steam power plants in such ships also provide steam to separate smaller turbines driving electric generators to supply electricity in the ship. Shipboard steam power plants can be either conventional or nuclear; the shipboard nuclear plants are mostly in the navy. There have been perhaps about a dozen turbo-electric ships in which a steam-driven turbine drives an electric generator which powers an electric motor for propulsion.
    In some industrial, large institutional facilities, or other populated areas, there are combined heat and power (CHP) plants, often called cogeneration plants, which produce both power and heat for facility or district heating or industrial applications. AC electrical power can be stepped up to very high voltages for long distance transmission with minimal loss of power. Steam and hot water lose energy when piped over substantial distance, so carrying heat or energy by steam or hot water is often only worthwhile within a local area or facility, such as steam distribution for a ship or industrial facility or hot water distribution in a local municipality.

    [edit] History

    Reciprocating steam engines have been used for mechanical power sources since the 18th Century, with notable improvements being made by James Watt. The very first commercial central electrical generating stations in New York and London, in 1882, also used reciprocating steam engines. As generator sizes increased, eventually turbines took over due to higher efficiency and lower cost of construction. By the 1920s any central station larger than a few thousand kilowatts would use a turbine prime mover.

    [edit] Efficiency

    Power is energy per time. The power output or capacity of an electric plant can be expressed in units of megawatts electric (MWe). The electric efficiency of a conventional thermal power station, considered as saleable energy (in MWe) produced at the plant busbars as a percent of the heating value of the fuel consumed, is typically 33% to 48% efficient. This efficiency is limited as all heat engines are governed by the laws of thermodynamics (See: Carnot cycle). The rest of the energy must leave the plant in the form of heat. This waste heat can go through a condenser and be disposed of with cooling water or in cooling towers. If the waste heat is instead utilized for district heating, it is called cogeneration. An important class of thermal power station are associated with desalination facilities; these are typically found in desert countries with large supplies of natural gas and in these plants, freshwater production and electricity are equally important co-products.
    Since the efficiency of the plant is fundamentally limited by the ratio of the absolute temperatures of the steam at turbine input and output, efficiency improvements require use of higher temperature, and therefore higher pressure, steam. Historically, other working fluids such as mercury have been experimentally used in a mercury vapour turbine power plant, since these can attain higher temperatures than water at lower working pressures. However, the obvious hazards of toxicity, and poor heat transfer properties, have ruled out mercury as a working fluid.

    [edit] Diagram of a typical coal-fired thermal power station


    Typical diagram of a coal-fired thermal power station 1. Cooling tower10. Steam Control valve19. Superheater2. Cooling water pump11. High pressure steam turbine20. Forced draught (draft) fan3. transmission line (3-phase)12. Deaerator21. Reheater4. Step-up transformer (3-phase)13. Feedwater heater22. Combustion air intake5. Electrical generator (3-phase)14. Coal conveyor23. Economiser6. Low pressure steam turbine15. Coal hopper24. Air preheater7. Condensate pump16. Coal pulverizer25. Precipitator8. Surface condenser17. Boiler steam drum26. Induced draught (draft) fan9. Intermediate pressure steam turbine18. Bottom ash hopper27. Flue gas stack




    [edit] Steam generator


    Schematic diagram of typical coal-fired power plant steam generator highlighting the air preheater (APH) location. (For simplicity, any radiant section tubing is not shown.)


    In fossil-fueled power plants, steam generator refers to a furnace that burns the fossil fuel to boil water to generate steam. In the nuclear plant field, steam generator refers to a specific type of large heat exchanger used in a pressurized water reactor (PWR) to thermally connect the primary (reactor plant) and secondary (steam plant) systems, which of course is used to generate steam. In a nuclear reactor called a boiling water reactor (BWR), water is boiled to generate steam directly in the reactor itself and there are no units called steam generators. In some industrial settings, there can also be steam-producing heat exchangers called heat recovery steam generators (HRSG) which utilize heat from some industrial process. The steam generating boiler has to produce steam at the high purity, pressure and temperature required for the steam turbine that drives the electrical generator. A fossil fuel steam generator includes an economizer, a steam drum, and the furnace with its steam generating tubes and superheater coils. Necessary safety valves are located at suitable points to avoid excessive boiler pressure. The air and flue gas path equipment include: forced draft (FD) fan, air preheater (APH), boiler furnace, induced draft (ID) fan, fly ash collectors (electrostatic precipitator or baghouse) and the flue gas stack.[1][2][3]
    Geothermal plants need no boiler since they use naturally occurring steam sources. Heat exchangers may be used where the geothermal steam is very corrosive or contains excessive suspended solids. Nuclear plants also boil water to raise steam, either directly generating steam from the reactor (BWR) or else using an intermediate heat exchanger (PWR).
    For units over about 200 MW capacity, redundancy of key components is provided by installing duplicates of the FD fan, APH, fly ash collectors and ID fan with isolating dampers. On some units of about 60 MW, two boilers per unit may instead be provided.



  2. [2]
    شكرى محمد نورى
    شكرى محمد نورى غير متواجد حالياً
    مشرف


    تاريخ التسجيل: Mar 2006
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    جزاك الله على الملاحظات القيّمة والاضافات المفيدة .

    تسلم لنا وما قصرت .

    تقبل فائق التقدير .

    البغدادي

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  3. [3]
    د.محمد باشراحيل
    د.محمد باشراحيل غير متواجد حالياً
    إستشاري الملتقى
    الصورة الرمزية د.محمد باشراحيل


    تاريخ التسجيل: Mar 2009
    المشاركات: 7,042
    Thumbs Up
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    اقتباس المشاركة الأصلية كتبت بواسطة شكرى محمد نورى مشاهدة المشاركة
    جزاك الله على الملاحظات القيّمة والاضافات المفيدة .

    تسلم لنا وما قصرت .

    تقبل فائق التقدير .

    البغدادي

    مهندس شكري

    الأخ والمشرف

    اشكر لك دائما تجاوبك وتفاعلك مع المواضيع

    بارك الله فيك

    تقبل تقديري وفائق التحيات

    *******
    وهذا بقية الموضوع من موسوعة ويكيبيديا

    Boiler furnace and steam drum
    Once water inside the boiler or steam generator, the process of adding the latent heat of vaporization or enthalpy is underway. The boiler transfers energy to the water by the chemical reaction of burning some type of fuel.
    The water enters the boiler through a section in the convection pass called the economizer. From the economizer it passes to the steam drum. Once the water enters the steam drum it goes down the downcomers to the lower inlet waterwall headers. From the inlet headers the water rises through the waterwalls and is eventually turned into steam due to the heat being generated by the burners located on the front and rear waterwalls (typically). As the water is turned into steam/vapor in the waterwalls, the steam/vapor once again enters the steam drum. The steam/vapor is passed through a series of steam and water separators and then dryers inside the steam drum. The steam separators and dryers remove water droplets from the steam and the cycle through the waterwalls is repeated. This process is known as natural circulation.
    The boiler furnace auxiliary equipment includes coal feed nozzles and igniter guns, soot blowers, water lancing and observation ports (in the furnace walls) for observation of the furnace interior. Furnace explosions due to any accumulation of combustible gases after a trip-out are avoided by flushing out such gases from the combustion zone before igniting the coal.
    The steam drum (as well as the superheater coils and headers) have air vents and drains needed for initial startup. The steam drum has internal devices that removes moisture from the wet steam entering the drum from the steam generating tubes. The dry steam then flows into the superheater coils.

    [edit] Superheater

    Fossil fuel power plants can have a superheater and/or reheater section in the steam generating furnace. Nuclear-powered steam plants do not have such sections but produce steam at essentially saturated conditions. In a fossil fuel plant, after the steam is conditioned by the drying equipment inside the steam drum, it is piped from the upper drum area into tubes inside an area of the furnace known as the superheater, which has an elaborate set up of tubing where the steam vapor picks up more energy from hot flue gases outside the tubing and its temperature is now superheated above the saturation temperature. The superheated steam is then piped through the main steam lines to the valves before the high pressure turbine.

    [edit] Reheater

    Power plant furnaces may have a reheater section containing tubes heated by hot flue gases outside the tubes. Exhaust steam from the high pressure turbine is rerouted to go inside the reheater tubes to pickup more energy to go drive intermediate or lower pressure turbines.

    [edit] Fuel preparation system

    In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers. The coal is next pulverized into a very fine powder. The pulverizers may be ball mills, rotating drum grinders, or other types of grinders.
    Some power stations burn fuel oil rather than coal. The oil must kept warm (above its pour point) in the fuel oil storage tanks to prevent the oil from congealing and becoming unpumpable. The oil is usually heated to about 100°C before being pumped through the furnace fuel oil spray nozzles.
    Boilers in some power stations use processed natural gas as their main fuel. Other power stations may use processed natural gas as auxiliary fuel in the event that their main fuel supply (coal or oil) is interrupted. In such cases, separate gas burners are provided on the boiler furnaces.

    [edit] Air path

    External fans are provided to give sufficient air for combustion. The forced draft fan takes air from the atmosphere and, first warming it in the air preheater for better combustion, injects it via the air nozzles on the furnace wall.
    The induced draft fan assists the FD fan by drawing out combustible gases from the furnace, maintaining a slightly negative pressure in the furnace to avoid backfiring through any opening. At the furnace outlet, and before the furnace gases are handled by the ID fan, fine dust carried by the outlet gases is removed to avoid atmospheric pollution. This is an environmental limitation prescribed by law, and additionally minimizes erosion of the ID fan.

    [edit] Auxiliary systems


    [edit] Fly ash collection

    Fly ash is captured and removed from the flue gas by electrostatic precipitators or fabric bag filters (or sometimes both) located at the outlet of the furnace and before the induced draft fan. The fly ash is periodically removed from the collection hoppers below the precipitators or bag filters. Generally, the fly ash is pneumatically transported to storage silos for subsequent transport by trucks or railroad cars.

    [edit] Bottom ash collection and disposal

    At the bottom of the furnace, there is a hopper for collection of bottom ash. This hopper is always filled with water to quench the ash and clinkers falling down from the furnace. Some arrangement is included to crush the clinkers and for conveying the crushed clinkers and bottom ash to a storage site.

    [edit] Boiler make-up water treatment plant and storage

    Since there is continuous withdrawal of steam and continuous return of condensate to the boiler, losses due to blowdown and leakages have to be made up to maintain a desired water level in the boiler steam drum. For this, continuous make-up water is added to the boiler water system. Impurities in the raw water input to the plant generally consist of calcium and magnesium salts which impart hardness to the water. Hardness in the make-up water to the boiler will form deposits on the tube water surfaces which will lead to overheating and failure of the tubes. Thus, the salts have to be removed from the water, and that is done by a water demineralising treatment plant (DM). A DM plant generally consists of cation, anion, and mixed bed exchangers. Any ions in the final water from this process consist essentially of hydrogen ions and hydroxide ions, which recombine to form pure water. Very pure DM water becomes highly corrosive once it absorbs oxygen from the atmosphere because of its very high affinity for oxygen.
    The capacity of the DM plant is dictated by the type and quantity of salts in the raw water input. However, some storage is essential as the DM plant may be down for maintenance. For this purpose, a storage tank is installed from which DM water is continuously withdrawn for boiler make-up. The storage tank for DM water is made from materials not affected by corrosive water, such as PVC. The piping and valves are generally of stainless steel. Sometimes, a steam blanketing arrangement or stainless steel doughnut float is provided on top of the water in the tank to avoid contact with air. DM water make-up is generally added at the steam space of the surface condenser (i.e., the vacuum side). This arrangement not only sprays the water but also DM water gets deaerated, with the dissolved gases being removed by an air ejector attached to the condenser.

    [edit] Steam turbine-driven electric generator


    Rotor of a modern steam turbine, used in a power station


    Main article: Turbo generator
    The steam turbine-driven generators have auxiliary systems enabling them to work satisfactorily and safely. The steam turbine generator being rotating equipment generally has a heavy, large diameter shaft. The shaft therefore requires not only supports but also has to be kept in position while running. To minimise the frictional resistance to the rotation, the shaft has a number of bearings. The bearing shells, in which the shaft rotates, are lined with a low friction material like Babbitt metal. Oil lubrication is provided to further reduce the friction between shaft and bearing surface and to limit the heat generated.

    [edit] Barring gear

    Barring gear (or "turning gear") is the mechanism provided to rotate the turbine generator shaft at a very low speed after unit stoppages. Once the unit is "tripped" (i.e., the steam inlet valve is closed), the turbine coasts down towards standstill. When it stops completely, there is a tendency for the turbine shaft to deflect or bend if allowed to remain in one position too long. This is because the heat inside the turbine casing tends to concentrate in the top half of the casing, making the top half portion of the shaft hotter than the bottom half. The shaft therefore could warp or bend by millionths of inches.
    This small shaft deflection, only detectable by eccentricity meters, would be enough to cause damaging vibrations to the entire steam turbine generator unit when it is restarted. The shaft is therefore automatically turned at low speed (about one percent rated speed) by the barring gear until it has cooled sufficiently to permit a complete stop.

    [edit] Condenser

    Main article: Surface condenser

    Diagram of a typical water-cooled surface condenser.[2][3][4][5]


    The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes.[2][6][7][8] The exhaust steam from the low pressure turbine enters the shell where it is cooled and converted to condensate (water) by flowing over the tubes as shown in the adjacent diagram. Such condensers use steam ejectors or rotary motor-driven exhausters for continuous removal of air and gases from the steam side to maintain vacuum.
    For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 oC where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum. Thus leaks of non-condensible air into the closed loop must be prevented. Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning.
    The condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or once-through water from a river, lake or ocean.

    [edit] Feedwater heater

    Main article: Feedwater heater

    A Rankine cycle with a two-stage steam turbine and a single feedwater heater.


    In the case of a conventional steam-electric power plant utilizing a drum boiler, the surface condenser removes the latent heat of vaporization from the steam as it changes states from vapour to liquid. The heat ******* (btu) in the steam is referred to as Enthalpy. The condensate pump then pumps the condensate water through a feedwater heater. The feedwater heating equipment then raises the temperature of the water by utilizing extraction steam from various stages of the turbine.[2][3]
    Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system.[9] This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feedwater is introduced back into the steam cycle.

    [edit] Superheater

    As the steam is conditioned by the drying equipment inside the drum, it is piped from the upper drum area into an elaborate set up of tubing in different areas of the boiler. The areas known as superheater and reheater. The steam vapor picks up energy and its temperature is now superheated above the saturation temperature. The superheated steam is then piped through the main steam lines to the valves of the high pressure turbine.

    [edit] Deaerator

    Main article: Deaerator

    Diagram of boiler feed water deaerator (with vertical, domed aeration section and horizontal water storage section


    A steam generating boiler requires that the boiler feed water should be devoid of air and other dissolved gases, particularly corrosive ones, in order to avoid corrosion of the metal.
    Generally, power stations use a deaerator to provide for the removal of air and other dissolved gases from the boiler feedwater. A deaerator typically includes a vertical, domed deaeration section mounted on top of a horizontal cylindrical vessel which serves as the deaerated boiler feedwater storage tank.[2][3][10]
    There are many different designs for a deaerator and the designs will vary from one manufacturer to another. The adjacent diagram depicts a typical conventional trayed deaerator.[10][11] If operated properly, most deaerator manufacturers will guarantee that oxygen in the deaerated water will not exceed 7 ppb by weight (0.005 cm³/L).[10][12]

    [edit] Auxiliary systems


    [edit] Oil system

    An auxiliary oil system pump is used to supply oil at the start-up of the steam turbine generator. It supplies the hydraulic oil system required for steam turbine's main inlet steam stop valve, the governing control valves, the bearing and seal oil systems, the relevant hydraulic relays and other mechanisms.
    At a preset speed of the turbine during start-ups, a pump driven by the turbine main shaft takes over the functions of the auxiliary system.

    [edit] Generator heat dissipation

    The electricity generator requires cooling to dissipate the heat that it generates. While small units may be cooled by air drawn through filters at the inlet, larger units generally require special cooling arrangements. Hydrogen gas cooling, in an oil-sealed casing, is used 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 start-up, 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 hydrogen pressure inside the casing is maintained slightly higher than atmospheric pressure to avoid outside air ingress. The hydrogen must be sealed against outward leakage where the shaft emerges from the casing. Mechanical seals around the shaft are installed with a very small annular gap to avoid rubbing between the shaft and the seals. Seal oil is used to prevent the hydrogen gas leakage to atmosphere.
    The generator also uses water cooling. Since the generator coils are at a potential of about 22 kV and water is conductive, an insulating barrier such as Teflon is used to interconnect the water line and the generator high voltage windings. Demineralized water of low conductivity is used.


    0 Not allowed!



  4. [4]
    د.محمد باشراحيل
    د.محمد باشراحيل غير متواجد حالياً
    إستشاري الملتقى
    الصورة الرمزية د.محمد باشراحيل


    تاريخ التسجيل: Mar 2009
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    تابع موضوع موسوعة ويكيبيديا


    Generator high voltage system
    The generator voltage ranges from 11 kV in smaller units to 22 kV in larger units. The generator high voltage leads are normally large aluminum channels because of their high current as compared to the cables used in smaller machines. They are enclosed in well-grounded aluminum bus ducts and are supported on suitable insulators. The generator high voltage channels are connected to step-up transformers for connecting to a high voltage electrical substation (of the order of 115 kV to 520 kV) for further transmission by the local power grid.
    The necessary protection and metering devices are included for the high voltage leads. Thus, the steam turbine generator and the transformer form one unit. In smaller units, generating at 11 kV, a breaker is provided to connect it to a common 11 kV bus system.

    [edit] Other systems


    [edit] Monitoring and alarm system

    Most of the power plant operational controls are automatic. However, at times, manual intervention may be required. Thus, the plant is provided with monitors and alarm systems that alert the plant operators when certain operating parameters are seriously deviating from their normal range.

    [edit] Battery supplied emergency lighting and communication

    A central battery system consisting of lead acid cell units is provided to supply emergency electric power, when needed, to essential items such as the power plant's control systems, communication systems, turbine lube oil pumps, and emergency lighting. This is essential for a safe, damage-free shutdown of the units in an emergency situation.

    [edit] Transport of coal fuel to site and to storage

    Main article: Fossil fuel power plant
    Most thermal stations use coal as the main fuel. Raw coal is transported from coal mines to a power station site by trucks, barges, bulk cargo ships or railway cars. Generally, when shipped by railways, the coal cars are sent as a full train of cars. The coal received at site may be of different sizes. The railway cars are unloaded at site by rotary dumpers or side tilt dumpers to tip over onto conveyor belts below. The coal is generally conveyed to crushers which crush the coal to about ¾ inch (6 mm) size. The crushed coal is then sent by belt conveyors to a storage pile. Normally, the crushed coal is compacted by bulldozers, as compacting of highly volatile coal avoids spontaneous ignition.
    The crushed coal is conveyed from the storage pile to silos or hoppers at the boilers by another belt conveyor system.

    [edit] See also

    Energy portal

    [edit] References

    1. <LI id=cite_note-0>^ British Electricity International (1991). Modern Power Station Practice: incorporating modern power system practice (3rd Edition (12 volume set) ed.). Pergamon. ISBN 0-08-040510-X. <LI id=cite_note-Babcock-1>^ a b c d e Babcock & Wilcox Co. (2005). Steam: Its Generation and Use (41st edition ed.). ISBN 0-9634570-0-4. <LI id=cite_note-Elliott-2>^ a b c d Thomas C. Elliott, Kao Chen, Robert Swanekamp (coauthors) (1997). Standard Handbook of Powerplant Engineering (2nd edition ed.). McGraw-Hill Professional. ISBN 0-07-019435-1. <LI id=cite_note-3>^ Air Pollution Control Orientation Course from website of the Air Pollution Training Institute <LI id=cite_note-4>^ Energy savings in steam systems Figure 3a, Layout of surface condenser (scroll to page 11 of 34 pdf pages) <LI id=cite_note-5>^ Air Pollution Control Orientation Course from website of the Air Pollution Training Institute <LI id=cite_note-6>^ Energy savings in steam systems Figure 3a, Layout of surface condenser (scroll to page 11 of 34 pdf pages) <LI id=cite_note-7>^ Robert Thurston Kent (Editor in Chief) (1936). Kents’ Mechanical Engineers’ Handbook (Eleventh edition (Two volumes) ed.). John Wiley & Sons (Wiley Engineering Handbook Series). <LI id=cite_note-Weston-8>^ Fundamentals of Steam Power by Kenneth Weston, University of Tulsa <LI id=cite_note-Spirax-9>^ a b c Pressurized deaerators <LI id=cite_note-10>^ Tray deaerating heaters
    2. ^ Deaerator Presentation


    [edit] External links

    Retrieved from "http://en.wikipedia.org/wiki/Thermal_power_station"
    Categories: Power station technology | Energy conversion | Chemical engineering | Steam power




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    الغلايات البخارية من الألف إلى الياء
    http://www.arab-eng.org/vb/t117151-4.html
    م. عبدالناصر عجوة
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    Pump Reference Guide Book
    http://www.arab-eng.org/vb/t7990.html
    العرندس
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    ملف فلاش عن محطات التوليد
    http://www.arab-eng.org/vb/t67836.html
    ابو يزن العسيري
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    كل شئ عن ال Heat Exchangers ...هذا كتابك
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    كتاب توليد الطاقة Power Generation Handbook
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    Hadary2006
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    http://www.arab-eng.org/vb/t128361.html
    amada557
    10
    Pressure Vessel Design
    http://www.arab-eng.org/vb/t6128.html
    Motaz_95
    11
    Heat Exchangers المبدلات الحرارية من الألف إلى Z
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    Motaz_95
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    http://www.arab-eng.org/vb/t125030.html
    مصطفى الوكيل
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    http://www.arab-eng.org/vb/archive/i...p/f-4-p-6.html
    Ahmed taye3
    15
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    http://www.arab-eng.org/vb/t52498.html
    Mosbhy98
    16
    شرح المحطات البخارية
    http://www.arab-eng.org/vb/t1840.html
    salt
    17
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    http://www.arab-eng.org/vb/t126406.html
    El-rayes
    18
    وتكملة للموضوع ملف عن المحطات
    http://www.arab-eng.org/vb/t126407.html
    El-rayes
    19
    حصريا وظهرياGas Turbine بالعربي مع صور توضيحية
    http://www.arab-eng.org/vb/t39847.html
    شوان غازي
    20
    المحطات البخارية من البداية الى النهاية
    http://www.arab-eng.org/vb/t8409.html
    salt
    21
    Heat exchanger
    دايناميك
    22
    محطات الطاقة الحرارية
    http://www.arab-eng.org/vb/t126457.html
    د.محمد باشراحيل



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