1. steam power plantBy :-Rakesh kumarAssistant professorElectrical Engineering Department.BABA HIRA SINGH BHATTAL INSTITUTE OFENGINEERING AND TECHNOLOGY LEHRAGAGA-148031 DISTT.SANGRUR (Pb.)

2. Essentials of Steam Power Plant EquipmentA steam power plant must have following equipment :(a) A furnace to burn the fuel.(b) Steam generator or boiler containing water.Heat generated in the furnace is utilized toconvert water into steam.(c) Main power unit such as an engine orturbine to use the heat energy of steam andperform work.(d) Piping system to convey steam and water. 3. The flow sheet of a thermal power plantconsists of the following four main circuits :(a) Feed water and steam flow circuit.(b) Coal and ash circuit.(c) Air and gas circuit.(d) Cooling water circuit. 4. A steam power plant using steam as workingsubstance works basically on Rankine cycle.Steam is generated in a boiler, expanded in theprime mover and condensed in the condenserand fed into the boiler again. 5. The different types of components used in steampower plant(a) High pressure boiler.(b) Prime mover .(c) Condensers and cooling towers .(d) Coal handling system .(e) Ash and dust handling system .(f) Draught system .(g) Feed water purification plant .(h) Pumping system .(i) Air preheater, economizer, super heater, feedheaters. 6. Types of steam Generators Horizontal vertical or inclined. Fire tube or water tube. Externally fired or internally fired. Forced circulation and natural circulation. High pressure or low pressure boiler. 7. Daltons law The partial pressure pressure of eachconstituent is that pressure which the gaswould exert if it occupied alone that volumeoccupied by the mixture at the sametemperature. 8. Factors that should be considered whileselecting the boiler Working pressure and quality of steamrequired. Steam generation rate. Floor area available. The portable load factor. Erection facilities. 9. Properties of good steam generators It should be absolutely reliable. It should occupy minimum space. It should be light in weight. Capable of quick starting. Erection of boiler should be simple. 10. Steam Power Plants are Classified as1. By fuel.2. By prime mover.3. By cooling tower. 11. Steam Power Plants are also Classified as;Central stations; the electrical energy available fromthese stations is meant for sale to the consumers whowish to purchase it.Industrial/ captive power stations; this type ofpower station is run by the manufacturing company forits own use and its output is not available for generalsale. 12. Jet condenser; low manufacturing cost. Lowupkeeps, requires small floor space and moreauxiliary power required.surface condenser; high manufacturingcost. high upkeeps, requires large floor space andless auxiliary power required. 13. Feed water heating improves overall plantefficiency.Quantity of steam produced by the boiler isincrease.Thermal stress due to cold water entering theboiler drum are avoided.Chance of boiler corrosion are decrease. 14. Dust collectors are Classified as;Mechanical dust collectors;(a)Wet type(scrubbers).Spray type, packed type and impingement type.(b) Dry type.Gravitational separators, cyclone separators,electrical dust collectors;Rod type and plate type. 15. DIFFERENT TYPES OF BOILERS USED INSTEAM POWER PLANTS horizontal, vertical or inclined. fire tube and water tube . Externally or internally fired. Forced or natural circulation. High pressure or low pressure. Stationary or portable. Single-tube and multi-tube. 16. Working diagram Thermalpower station. 17. CsaturatedwaterSteam Turbine Power Planthot gasesSteamTurbineGencompressedwatersuperheatedsteamCondenserPumpcooling watersaturatedsteamSteam Generator(Boiler / Furnace) 18. Schematic arrangement of equipment of asteam power station. Coal received in coal storage yard of powerstation is transferred in the furnace by coalhandling unit. Heat produced due to burning ofcoal is utilized in converting water contained inboiler drum into steam at suitable pressure andtemperature. The steam generated is passedthrough the superheater. 19. Superheated steam then flows through theturbine. After doing work in the turbine thepressure of steam is reduced. Steam leavingthe turbine passes through the condenserwhich is maintained the low pressure ofsteam at the exhaust of turbine. 20. Steam pressure in the condenser depends uponflow rate and temperature of cooling water andon effectiveness of air removal equipment.Water circulating through the condenser may betaken from the various sources such as river, lakeor sea. If sufficient quantity of water is notavailable the hot water coming out of thecondenser may be cooled in cooling towers andcirculated again through the condenser. Bled steam taken from the turbine at suitableextraction points is sent to low pressure and highpressure water heaters. 21. Air taken from the atmosphere is firstpassed through the air pre-heater, where it isheated by flue gases. The hot air then passesthrough the furnace. The flue gases after passing over boiler andsuperheater tubes, flow through the dustcollector and then through economiser, airpre-heater and finally they are exhausted tothe atmosphere through the chimney. 22. Disadvantage of steam power plant Maintenance and operating cost are high. Long time required for erection and putting intoaction . Large quantity of water is required. Great difficulty experienced in coal handling . Efficiency decreases rapidly below about 75percent load. 23. Mechanical equipment in Thermalpower station.BOILERECONOMISERTURBINESUPER HEATERAIR PREHEATERCONDENSER 24. SuperheaterThe superheater consists of a superheaterheader and superheater elements. Steam fromthe main steam pipe arrives at the saturatedsteam chamber of the superheater header and isfed into the superheater elements.Superheated steam arrives back at thesuperheated steam chamber of the superheaterheader and is fed into the steam pipe to thecylinders. Superheated steam is more expansive. 25. Advantages of superheated steam Capacity to do work is increased withoutincreasing its pressure. High temperature of super heated steamresults in an increase in thermal efficiency. Heat losses due to condensation of stem oncylinder walls are avoided to a great extent. Does not produce corrosion effect onturbine. 26. Superheater It is a heating device. It is used to raise temp of steam at constpressure. It removes even last traces of moisture. 27. Classification of super heater Convection. Radiation. Combination of convection and radiation. 28. Reheater The function of reheater is similar to thesuperheater in that it serves to elevate thesteam temperature. Primary steam is suppliedto the high pressure turbine. After passing through the high pressureturbine, the steam is returned to the steamgenerator for reheating (in a reheater) afterwhich it is sent to the low pressure turbine. Asecond reheat cycle may also be provided. 29. Soot Blowers The fuel used in thermal power plants causessoot and this is deposited on the boiler tubes,economizer tubes, air pre heaters, etc. This drastically reduces the amount of heattransfer of the heat exchangers. Soot blowerscontrol the formation of soot and reduce itscorrosive effects. The types of soot blowers are fixed type, whichmay be further classified into lane type andmass type depending upon the type of spray andnozzle used. 30. Condenser The use of a condenser in a power plant is toimprove the efficiency of the power plant bydecreasing the exhaust pressure of the steambelow atmosphere. Another advantage of the condenser is that thesteam condensed may be recovered to provide asource of good pure feed water to the boiler andreduce the water softening capacity to aconsiderable extent. A condenser is one of theessential components of a power plant. 31. Functions of Condensers The main purposes of the condenser are tocondense the exhaust steam from the turbinefor reuse in the cycle and to maximize turbineefficiency by maintaining proper vacuum. As the operating pressure of the condenser islowered (vacuum is increased), the enthalpydrop of the expanding steam in the turbine willalso increase. This will increase the amount ofavailable work from the turbine (electricaloutput). 32. Cooling Tower The importance of the cooling tower is feltwhen the cooling water from the condenser hasto be cooled. The cooling water after condensing the steambecomes hot and it has to be cooled as itbelongs to a closed system. The Cooling towersdo the job of decreasing the temperature of thecooling water after condensing the steam in thecondenser. 33. Cooling Towers have one function : Remove heat from the water dischargedfrom the condenser so that the water can bedischarged to the river or re-circulated andreused. 34. A cooling tower extracts heat from water byevaporation. In an evaporative coolingtower, a small portion of the water beingcooled is allowed to evaporate into a movingair stream to provide significant cooling tothe rest of that water stream. 35. Cooling Towers are commonly used toprovide lower than ambient watertemperatures and are more cost effective andenergy efficient than most other alternatives. The smallest cooling towers are structured foronly a few litres of water per minute while thelargest cooling towers may handle upwards ofthousands of litres per minute. The pipes areobviously much larger to accommodate thismuch water in the larger towers and canrange up to 12 inches in diameter. 36. Advantages of regenerative cycle Improve overall plant efficiency. Protect boiler corrosion. Avoid the thermal stresses due to cold waterentering the boiler . Increased the quantity of steam produced byboiler. 37. Function of economizer To extract a part of heat from the fuel gascoming out of the boiler.To use heat for heating feed water to theboiler. To increases the efficiency of boiler. 38. The economizer is a feed water heater,deriving heat from the flue gases. Thejustifiable cost of the economizer depends onthe total gain in efficiency. In turn thisdepends on the flue gas temperature leavingthe boiler and the feed water inlettemperature. 39. Air Pre-heater The flue gases coming out of the economizeris used to preheat the air before supplying itto the combustion chamber. An increase inair temperature of 20 degrees can beachieved by this method. The pre heated airis used for combustion and also to dry thecrushed coal before pulverizing. 40. Advantages of mechanical handling Higher reliability. Less labour required. Operation is easy and smooth. Economical for large capacity plant. Losses in transport are minimised. Easily started. 41. Disadvantages of mechanical handling Need continuous maintenance and repair. Capital cost of plant is increased. 42. Working diagram Thermalpower station. 43. Side view Thermal power station. 44. CTotalHeatsaturatedwaterSteam Turbine Power PlantGencompressedwatersuperheatedsteaminSteam GeneratorLoss???Where???cooling waterPumpTotalSteamTurbineCondensersaturatedsteamhot gasesWorkoutWorkin 45. R. Shanthini 15Aug 2010According to the2nd Law of Thermodynamicswhen heat is converted into work,part of the heat energy must be wastedPower generationtypeUnit size(MW)Energy wasted(MW)Diesel engine 10 - 30 7 22Gas Turbine 50 - 100 36 78Steam Turbine 200 - 800 120 560Combined (ST & GT) 300 - 600 150 380Nuclear (BWR & PWR) 500 - 1100 330 760 46. The Simple Ideal Rankine Cycle9-1 The McGraw-Hill Companies, Inc.,1998 47. How can We Increase the Efficiency of theRankine cycle? Rankine cycle efficiency can be increased byincreasing average temperature at whichheat is transferred to the working fluid inthe boiler or decreasing the averagetemperature at which heat is rejected fromthe working fluid in the condenser. That is,the average fluid temperature should be ashigh as possible during heat addition and aslow as possible during heat rejection. 48. The three ways by which efficiency of theRankine cycle can be increased are :(a) Lowering the condenser pressure.(b) Superheating the steam to hightemperatures.(c) Increasing the boiler pressure. 49. The thermal efficiency of the Rankine cyclecan be increased by increasing the averagetemperature at which heat is added to theworking fluid and/or by decreasing theaverage temperature at which heat isrejected to the cooling medium. The averagetemperature during heat rejection can bedecreased by lowering the turbine exitpressure. 50. Consequently, the condenser pressure of mostvapor power plants is well below theatmospheric pressure. The averagetemperature during heat addition can beincreased by raising the boiler pressure or bysuperheating the fluid to high temperatures.There is a limit to the degree of superheating,however, since the fluid temperature is notallowed to exceed a metallurgically safe value. 51. Superheating has the added advantage ofdecreasing the moisture content of the steam atthe turbine exit. Lowering the exhaust pressureor raising the boiler pressure, however, increasesthe moisture content. To take advantage of theimproved efficiencies at higher boiler pressuresand lower condenser pressures, steam is usuallyreheated after expanding partially in the high-pressureturbine. 52. This is done by extracting the steam afterpartial extraction in the high-pressureturbine, sending it back to the boiler whereit is reheated at constant pressure, andreturning it to the low-pressure turbine forcomplete expansion to the condenserpressure. 53. The average temperature during the reheatprocess, and thus the thermal efficiency ofthe cycle, can be increased by increasing thenumber of expansion and reheat stages. Asthe number of stages is increased, theexpansion and reheat processes approach anisothermal process at maximumtemperature. Reheating also decreases themoisture content at the turbine exit. 54. Another way of increasing the thermalefficiency of the Rankine cycle is byregeneration. During a regeneration process,liquid water (feed water) leaving the pumpis heated by some steam bled off the turbineat some intermediate pressure in devicescalled feed water heaters. 55. The two streams are mixed in open feedwater heaters, and the mixture leavesas a saturated liquid at the heaterpressure. In closed feed water heaters,heat is transferred from the steam tothe feed water without mixing. 56. The production of more than one usefulform of energy (such as process heat andelectric power) from the same energy sourceis called cogeneration. Cogeneration plantsproduce electric power while meeting theprocess heat requirements of certainindustrial processes. 57. This way, more of the energytransferred to the fluid in the boileris utilized for a useful purpose. Thefaction of energy that is used foreither process heat or powergeneration is called the utilizationfactor of the cogeneration plant. 58. The overall thermal efficiency of a powerplant can be increased by using binarycycles or combined cycles. A binary cycleis composed of two separate cycles, one athigh temperatures (topping cycle) and theother at relatively low temperatures. 59. The most common combined cycle is the gas-steamcombined cycle where a gas-turbinecycle operates at the high-temperature rangeand a steam-turbine cycle at the low-temperaturerange. Steam is heated by thehigh-temperature exhaust gases leaving thegas turbine. Combined cycles have a higherthermal efficiency than the steam- or gas-turbinecycles operating alone. 60. Selection of plant site The selection of plant site for thermal powerplant compared with hydro-power plant ismore difficult as it involves number offactors to be considered for its economicjustification.A few important factors to be considered forthe selection of thermal power plants. 61. Selection of plant siteAVAILABILITY OF COAL.Huge quantity of coal is required forlarge thermal plants.ASH DISPOSAL FACILITIES.SPACE REQUIREMENT.NATURE OF LAND.AVAILABILITY OF WATER. 62. Selection of plant siteTRANSPORT FACILITYIES.AVAILABILITY OF LABOUR.PUBLIC PROBLEMS. SIZE OF THE PLANT. 63. ABOUT ELECTROSTATICPRECIPITATORNowadays, the environment protection hasbecome a crucial problem and theauthorities are requested to set increasinglymore stringent limits , one of which is theemissions from the industrial plants of solidparticulate and other gaseous pollutants. 64. ABOUT ELECTROSTATIC PRECIPITATORWhat is ESPElectrostatic precipitator (ESP) is a widelyused device in so many different domainsto remove the pollutant particulates,especially in industrial plants. 65. HOW ESP WORKSMain process of ESPGenerally, the processes ofelectrostatic precipitator are known asthree main stages: particle charging,transport and collection. 66. Schematic of wire-plate ESPSchematic of wire-plate electrostaticprecipitator 67. Mechanism of ESPMechanism of electrostatic precipitator 68. PROCESS OF Particle chargingParticle charging is the first andforemost beginning in processes.As the voltage applied on precipitatorreach threshold value, the space insidedivided into ionization region and driftregion. 69. The electric field magnitude around thenegative electrode is so strong that theelectrons escape from molecule.Under the influence of electric field, the positiveions move towards the corona, while thenegative ions and electrons towards thecollecting plates. 70. Particle transportIn the moving way, under the influence ofelectric field, negative ions cohere and charge theparticles, make the particles be forced towardscollecting-plate. 71. Particle collectionAs soon as the particles reach the plate,they will be neutralized and packed bythe succeeded ones subsequently. Thecontinuous process happens, as a result,particles are collected on the collectingplate. 72. 72IntroductionWhat is a Boiler? Vessel that heats water to become hot wateror steam At atmospheric pressure water volumeincreases 1,600 times Hot water or steam used to transfer heat to aprocess 73. The boiler is a rectangular furnaceabout 50 feet (15 m) on a side and 130 feet(40 m) tall. Its walls are made of a web ofhigh pressure steel tubes about 2.3 inches(58 mm) in diameter. 74. A boiler should fulfill the following requirements(a)Safety : The boiler should be safe underoperating conditions.(b) Accessibility : The various parts of theboiler should be accessible for repair andmaintenance.(c) Capacity : The boiler should be capable ofsupplying steam according to the requirements. 75. (d) Efficiency : To permit efficient operation, the boilershould be able to absorb a maximum amount of heatproduced due to burning of fuel in the furnace.(e) It should be simple in construction and itsmaintenance cost should be low.(f) Its initial cost should be low.(g) The boiler should have no joints exposed to flames.(h) The boiler should be capable of quick starting andloading. 76. IntroductionBURNERWATERSOURCEBRINESOFTENERSBOILERECO-NOMI-ZERCHEMICAL FEEDFUELVENTBLOW DOWNSEPARATOREXHAUST GAS VENTSTEAM TOPROCESSSTACK DEAERATORPUMPSFigure: Schematic overview of a boiler room 77. Types of BoilersWhat Type of Boilers Are There?1. Fire Tube Boiler2. Water Tube Boiler3. Packaged Boiler4. Fluidized Bed (FBC) Boiler5. Stoker Fired Boiler6. Pulverized Fuel Boiler7. Waste Heat Boiler8. Thermic Fluid Heater (not a boiler!) 78. The boilers can be classified according to thefollowing criteria.According to flow of water and hotgases :(a) Water tube(b) Fire tube. 79. Type of Boilers1. Fire Tube Boiler Relatively small steamcapacities (12,000 kg/hour) Low to medium steampressures (18 kg/cm2) Operates with oil, gas or solidfuels 80. Type of Boilers2. Water Tube Boiler Used for high steam demandand pressure requirements Capacity range of 4,500 120,000 kg/hour Combustion efficiencyenhanced by induced draftprovisions Lower tolerance for waterquality and needs watertreatment plant 81. 3. Packaged BoilerOilBurnerToChimney Comes in complete package Features High heat transfer Faster evaporation Good convective heattransfer Good combustion efficiency High thermal efficiency Classified based on number ofpasses 82. Working of power plantPulverized coal is air-blown into thefurnace from fuel nozzles at the fourcorners and it rapidly burns, forming alarge fireball at the center. The thermalradiation of the fireball heats the waterthat circulates through the boiler tubes nearthe boiler perimeter. 83. The water circulation rate in the boileris three to four times the throughput andis typically driven by pumps. As thewater in the boiler circulates it absorbsheat and changes into steam at 700 F(371 C) and 3,200 psi 84. The water enters the boiler through asection in the convection pass called theeconomizer. From the economizer itpasses to the steam drum. Once thewater enters the steam drum it goes downto the lower inlet water wall headers. 85. From the inlet headers the water risesthrough the water walls and is eventuallyturned into steam due to the heat beinggenerated by the burners located on thefront and rear water walls (typically). Asthe water is turned into steam/vapor in thewater walls, the steam/vapor once againenters the steam drum. 86. The steam/vapor is passed through a series ofsteam and water separators and then dryersinside the steam drum.The steam separators and dryers removewater droplets from the steam and the cyclethrough the water walls is repeated. This processis known as natural circulation. 87. super heaterFossil fuel power plants can have a superheater and/or re-heater section in the steamgenerating furnace. In a fossil fuel plant,after the steam is conditioned by the dryingequipment inside the steam drum, it is pipedfrom the upper drum area into tubes insidean area of the furnace known as the superheater, 88. which has an elaborate set up of tubing wherethe steam vapor picks up more energy fromhot flue gases outside the tubing and itstemperature is now superheated above thesaturation temperature. The superheatedsteam is then piped through the main steamlines to the valves before the high pressureturbine. 89. Condenser The condenser condenses the steam from theexhaust of the turbine into liquid to allow itto be pumped. If the condenser can be madecooler, the pressure of the exhaust steam isreduced and efficiency of the cycleincreases. 90. For best efficiency, the temperature in thecondenser must be kept as low aspractical in order to achieve the lowestpossible pressure in the condensingsteam. 91. Since the condenser temperature can almostalways be kept significantly below 100 Cwhere the vapor pressure of water is muchless than atmospheric pressure, the condensergenerally works under vacuum. Thus leaksof non-condensible air into the closed loopmust be prevented. 92. The condenser generally uses eithercirculating cooling water from a coolingtower to reject waste heat to theatmosphere, or once-through water from ariver, lake or ocean. 93. The condenser tubes are made of brassor stainless steel to resist corrosionfrom either side. Nevertheless they maybecome internally fouled during operationby bacteria or algae in the cooling water orby mineral scaling, all of which inhibit heattransfer and reduce thermodynamicefficiency. 94. Many plants include an automaticcleaning system that circulates spongerubber balls through the tubes to scrubthem clean without the need to take thesystem off-line. 95. Re heaterPower plant furnaces may have a re heatersection containing tubes heated by hot fluegases outside the tubes. Exhaust steam fromthe high pressure turbine is rerouted to goinside the re heater tubes to pickup moreenergy to go drive intermediate or lowerpressure turbines. 96. Main pollutants from a power systemNon toxic dust Sulphurous anhydrideCarbon monoxide Nitrogen dioxide Soot (fly ash)Hydrogen sulphide Pollution can be define as the contamination of soil,air and water with undesirable amount of material andheat. 97. Acid rain; the rain which contain acid as itsconstituents, brings all the acid down from highabove the environment.Contaminant; it is the another name ofpollution. It is undesirable substances whichmay be physical, chemical or biological.Pollutant; these are undesirable substancespresent in the environment these can be NO2,SO2, CO2,smoke,salt, bacteria. 98. Bad effects of thermal pollution Lot of heat is injected into biosphere fromthermal power plant, through exhaust gasesand waste water. The major problem is theeffect of discharge of large quantity ofheated wasted water into natural waterbasins. Hot water raises the temperatureand disturbs the natural ecological balance 99. Advantages of combined operation of plantsGreater reliability of supply to the consumers.Avoid complete shut down. The overall cost of energy per unit of aninterconnected system is less. There is a more effective use of transmissionline facilities. Less capital investment required. Less expenses on supervision, operation andmaintenance. 100. Due to limited generating capacity dieselpower stations is not suitable for base loadplants. Nuclear power stations is not suitable forpeak load plants.Incremental rate curve shows that asoutput power increases, cost of plantalso increases.