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COAL BASED POWER PLANT UNIT 1 - POWER PLANT ENGINEERING

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THIS WILL COVERS THE VAPOUR POWER CYCLES, THERMAL POWER PLANT LAYOUT & ITS COMPONENTS

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COAL BASED POWER PLANT UNIT 1 - POWER PLANT ENGINEERING

  1. 1. POWER PLANT ENGINEERING S.BALAMURUGAN - M.E ASSISTANT PROFESSOR MECHANICAL ENGINEERING AAA COLLEGE OF ENGINEERING & TECHNOLOGY UNIT 1 – COAL BASED THERMAL POWER PLANTS
  2. 2. VAPOUR POWER CYCLES ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET CARNOT CYCLE - Theoretical thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 RANKINE CYCLE - Fundamental operating cycle of all power plants where an operating fluid is continuously evaporated and condensed. REHEAT CYCLE REGENERATION CYCLE BINARY VAPOUR CYCLE
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  7. 7. REGENERATIVE CYCLE REASON ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  8. 8. REGENERATIVE CYCLE ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  9. 9. REHEAT CYCLE T-S DIAGRAM OF WATER SENSIBLE HEAT – It is the energy required to change the temperature of a substance with no phase change. LATENT HEAT - It is the energy absorbed by or released from a substance during a phase change from a gas to a liquid or a solid or vice versa. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET The latent heat of vaporization of water is about 2,260 J/g (100deg) The latent heat of fusion of water is about 334 J/g (0deg)
  10. 10. REHEAT CYCLE ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  11. 11. THERMAL POWER PLANT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  12. 12. INTRODUCTION A Thermal Power Plant converts the heat energy of coal into electrical energy. Coal is burnt in a boiler which converts water into steam. The expansion of steam in turbine produces mechanical power which drives the alternator coupled to the turbine.Thermal Power Plants contribute maximum to the generation of Power for any country . Thermal Power Plants constitute 75.43% of the total installed captive and non-captive power generation in India . In thermal generating stations coal, oil, natural gas etc. are employed as primary sources of energy. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  14. 14. GENERAL LAYOUT OF THERMAL POWER STATION ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  16. 16. Diagram of a typical coal-fired thermal power station
  17. 17. COAL HANDLING PLANT •The function of coal handling plant is automatic feeding of coal to the boiler furnace. • A thermal power plant burns enormous amounts of coal. •A 200MW plant may require around 2000 tons of coal daily • Pulverizer • Burner • Seperator • Drier, crusher ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  18. 18. FUEL HANDLING SYSTEM ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  23. 23. FUEL HANDLING SYSTEM ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET Coal – In plant Handling
  24. 24. COAL PREPARATION PLANT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  28. 28. MAGNETIC SEPARATOR ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  32. 32. BUCKET ELEVATOR SCREW CONVEYOR ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  34. 34. ASH HANDLING SYSTEM  It is an important aspect in coal fired steam power plant, the ash gives even up to 10-20% of the coal used to burn.  Tonnes of ash have to handled per day in large power stations, needs mechanical systems. Reasons for difficult to Handling ash  Hot ash from furnace  Abrasive nature, wear out the container  dusty, irritative to handle  Produce poisonous gas & corrosive acid when mixed with water  Clinker formation ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  35. 35. ASH HANDLING SYSTEM ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  36. 36. MECHANICAL ASH HANDLING SYSTEM ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  37. 37. HYDRAULIC ASH HANDLING SYSTEM ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  38. 38. PNEUMATIC ASH HANDLING SYSTEM ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET Steam jet System, Horizontal distance 200m, Vertical distance – 30 m
  39. 39. ASH HANDLING PLANT The percentage of ash in coal varies from 5% in good quality coal to about 40% in poor quality coal Power plants generally use poor quality of coal , thus amount of ash produced by it is pretty large A modern 2000MW plant produces about 5000 tons of ash daily The stations use some conveyor arrangement to carry ash to dump sites directly or for carrying and loading it to trucks and wagons which transport it to the site of disposal ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  40. 40. BOILER • A boiler or steam generator is a closed vessel in which water under pressure, is converted into steam. •Always designed to absorb maximum amount of heat released in the process of combustion. Types of Boilers 1. Horizontal, Vertical & Inclined Boiler (Based on Axis) – Horizontal Boiler can be easily inspected & Repaired, it occupied more space. 2. Fire tube Boiler – Hot gas inside tube, Water surrounds the tubes. (Locomotive Boiler) 3. Water tube Boiler – Water is inside the tube, Hot gases surrounds them. 4. Forced circulation Boiler – Circulation of water is done by a forced pump. (Benson, Lamont Boiler) 5. Natural circulation Boiler – Circulation of water in the boiler takes place due to natural convention current produced by the application of heat. 6. High Pressure Boiler – Produces steam at pressure of 80 bar & above. (Benson Boiler, Lamont Boiler) ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  41. 41. BOILER ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET SUBCRITICAL BOILER = ECONOMISER, EVAPORATOR, SUPER HEATER SUPER CRITICAL BOILER = ECONOMISER, SUPER HEATER 500MW PLANTS = 235BAR & 540 ° C
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  44. 44. Capacity = 45-50 tonnes/h Pressure = 130 bar Temperature = 500° C ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  45. 45. Capacity = 100 tonnes/h Pressure = 140 bar Temperature = 500° C ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  46. 46. Capacity = 150 tonnes/h Pressure = 235 bar Temperature = 650° C CRITICAL PRESSURE LATENT HEAT IS ZERO BUBBLING FORMATION ELIMINATED At 225 bar, steam & Bubbles have same density ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  47. 47. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET 70 - 100μ
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  49. 49. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET Coal Particles steadily ignited at 1700°C, leads to formation of NOx
  50. 50. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET High temperature leads to corrosion & Erosion. High ash content coal cannot be used(30-35%)
  51. 51. FLUIDISED BED COMBUSTION 90% Inert material (Sintered ash, Fused alumina, sand, Mullite & Zirconia) – Control the Bed Temperature (800°C) Low combustion temperature – Avoid formation of Nitric oxide & Nitrogen oxide Cost of Crushing the fuel is reduced Other systems unstable for over 48% of ash content, but it accepts 70% ash containing coal Pollution is controlled & High sulphur coal is possible Ex, 120MW plant, Savings 10% in Operation & 15% in Capital cost. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET (Particle Size = up to 12mm 70% Ash Coal) Up to 50mm size 150 tonnes/hr 150bar, 400°C
  52. 52. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET Pressure = 10bar – High Heat Transfer Rates Gas Velocity = B/W Bubbling Velocity of coarse particle & Terminal velocity of Finer Particle. PFBC = 1 m/s, ABFBC = 1.3 – 3.5 m/s
  53. 53. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET Products of combustion gives large proportion of unburned carbon particles. 10-15 times high volumetric heat releases 2-3 times higher surface heat transfer rates than conventional boiler Compact Size
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  56. 56.  Tuyeres - a nozzle through which air is forced into furnace.  The basic difference between coal and coke is that coal is the natural source(chiefly hydrogen, with smaller quantities of sulphur, oxygen, and nitrogen) and coke is the derivative product produced by destructive distillation. Both are used as fuel, but coke contains a higher carbon content and few impurities. Distillation is the process of separating the components or substances from a liquid mixture by selective boiling and condensation ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  60. 60. PULVERISING PLANT In modern thermal power plant , coal is pulverised i.e. ground to dust like size and carried to the furnace in a stream of hot air. Pulverising is a means of exposing a large surface area to the action of oxygen and consequently helping combustion. Pulverising mills are further classified as: 1. Ball mill 2. Ball & Race mill 3. Bowl mill 4. Impact mill ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  62. 62. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET 14 kwh / tonnes
  63. 63. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET 5 kwh / tonnes
  64. 64. TURBINE – FULL VIEW ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET • specific speed value for a turbine is the speed of a geometrically similar turbine which would produce unit power (one kilowatt) under unit head (one meter). • The specific speed of a turbine is given by the manufacturer (along with other ratings) and will always refer to the point of maximum efficiency.
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  67. 67. COMPOUNDING OF TURBINES  The method in which energy from steam is extracted in more than single stage is called Compounding. A multi-stage turbine i.e having more than one set of rotors and nozzles is called compounded turbine.  The steam produced in the boiler has sufficiently high enthalpy when superheated.  In all turbines the blade velocity is directly proportional to the velocity of the steam passing over the blade.  if the entire energy of the steam is extracted in one stage, i.e. if the steam is expanded from the boiler pressure to the condenser pressure in a single stage, then its velocity will be very high. Hence the velocity of the rotor (to which the blades are keyed) can reach to about 30,000 rpm, which is pretty high for practical uses because of very high vibration. Moreover at such high speeds the centrifugal forces are immense, which can damage the structure. Hence, compounding is needed.  The high velocity which is used for impulse turbine just strikes on single ring of rotor that cause wastage of steam ranges 10% to 12%. To overcome the wastage of steam compounding of steam turbine is used. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  71. 71. GOVERNING OF STEAM TURBINES  Steam Turbine Governing is the procedure of monitoring and controlling the flow rate of steam into the turbine with the objective of maintaining its speed of rotation as constant. The flow rate of steam is monitored and controlled by interposing valves between the boiler and the turbine. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  72. 72. THROTTLE GOVERNING The pressure of steam is reduced at the turbine entry thereby decreasing the availability of energy. In this method steam is passed through a restricted passage thereby reducing its pressure across the governing valve. The flow rate is controlled using a partially opened steam control valve. The reduction in pressure leads to a throttling process(h1=h2, h=u + Pv) in which the enthalpy of steam remains constant. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  73. 73.  In nozzle governing the flow rate of steam is regulated by opening and shutting of sets of nozzles rather than regulating its pressure.  In actual turbine, nozzle governing is applied only to the first stage whereas the subsequent stages remain unaffected.  No regulation to the pressure is applied, the advantage of this method lies in the exploitation of full boiler pressure and temperature. NOZZLE GOVERNING ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  74. 74.  When the turbine is overloaded for short durations. During such operation, bypass valves are opened and fresh steam is introduced into the later stages of the turbine. This generates more energy to satisfy the increased load. BY-PASS GOVERNING ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  75. 75. DRAUGHT SYSTEM • The circulation of air is caused by a difference in pressure, known as Draught. • Draught is a differential pressure b/w atmosphere and inside the boiler. • It is necessary to cause the flow of gases through boiler setting. Functions To supply sufficient quantity of air through the furnace for complete combustion To remove the gaseous products of combustion from the furnace To move and exhaust the product of combustion to the atmosphere through the chimney 1. Natural draft - Through Chimney 2. Mechanical draft a) Forced draught b) Induced draught c) Balanced draught ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  76. 76. NATURAL DRAFT - THROUGH CHIMNEY ΔP = g H ( ρa – ρg ) ΔP – draught or pressure difference, Pa g – Acceleration due to gravity, m/s2 H – Chimney height, m ρa – Density of atmosphere air, kg/m3 ρg – Density of gas inside the chimney, kg/m3 ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET 10-20 mm of water 30-350 mm of water
  77. 77. POSITIVE DRAUGHT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  78. 78. Limitations of Forced & Induced draught system overcome by this system (Inspection situation) ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  79. 79. COOLING TOWERS AND PONDS o A condenser needs huge quantity of water to condense the steam . o Most plants use a closed cooling system where warm water coming from condenser is cooled and reused oSmall plants use spray ponds and medium and large plants use cooling towers. oCooling tower is a steel or concrete hyperbolic structure having a reservoir at the base for storage of cooled water oHeight of the cooling tower may be 150 m or so and diameter at the base is 150 m ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  80. 80. Main Features of Cooling Towers ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET • Frame and casing: support exterior enclosures • Fill: facilitate heat transfer by maximizing water / air contact - Splash fill - Film fill • Cold water basin: receives water at bottom of tower
  81. 81. 81 • Drift eliminators: capture droplets in air stream • Air inlet: entry point of air • Louvers: equalize air flow into the fill and retain water within tower • Nozzles: spray water to wet the fill • Fans: deliver air flow in the tower Components of a cooling tower ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  82. 82. • Hot air moves through tower • Fresh cool air is drawn into the tower from bottom • No fan required • Concrete tower <200 m • Used for large heat duties • Large fans to force air through circulated water • Water falls over fill surfaces: maximum heat transfer • Cooling rates depend on many parameters • Large range of capacities • Can be grouped, e.g. 8-cell tower Types of Cooling Towers NATURAL DRAFT COOLING TOWERS MECHANICAL DRAFT COOLING TOWERS ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  83. 83. 83 Types of Cooling Towers Natural Draft Cooling Towers Cross flow • Air drawn across falling water • Fill located outside tower Counter flow • Air drawn up through falling water • Fill located inside tower ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  84. 84. Types of Cooling Towers Three types • Forced draft • Induced draft cross flow • Induced draft counter flow Mechanical Draft Cooling Towers ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  85. 85. • Air blown through tower by centrifugal fan at air inlet • Advantages: suited for high air resistance & fans are relatively quiet • Disadvantages: recirculation due to high air-entry and low air-exit velocities Forced Draft Cooling Towers Mechanical Draft Cooling Towers ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  86. 86. • Two types • Cross flow • Counter flow • Advantage: less recirculation than forced draft towers • Disadvantage: fans and motor drive mechanism require weather-proofing Induced Draft Cooling Towers Mechanical Draft Cooling Towers ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  87. 87. Mechanical Draft Cooling Towers • Hot water enters at the top • Air enters at bottom and exits at top • Uses forced and induced draft fans Induced Draft Counter Flow CT ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  88. 88. • Water enters top and passes over fill • Air enters on one side or opposite sides • Induced draft fan draws air across fill Induced Draft Cross Flow CT Mechanical Draft Cooling Towers ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  91. 91. Binary Vapour Cycle - Mercury Mercury, Diphenyl ether, Aluminium Bromide & Ammonium Chloride – High Critical Temperature & Low critical pressure. At 12 Bar, saturation temp of water is 187°C, for Mercury 550°C Mercury – At 21 bar - 589°C Saturation Temperature at Atmospheric pressure is 357°C, can’t use mercury alone, so we go for Binary Cycle Topping Cycle – High Temperature Cycle Bottoming Cycle – Low Temperature Cycle ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  93. 93. FEED WATER TREATMENT  RawWater contains dissolved salts, Un dissolved salts or Suspended impurities.  It is necessary to remove harmful salts dissolved in the water.  Need for FeedWaterTreatment  Scaling on inside wall of different heat exchangers due to deposition of salts  Suspended impurities create more pressure in the boiler leads to explosion  Dissolved salts react with boiler & tubes, there by corrode the surface  Corrosion damage the turbine blades. Define PH. Why high pH value is preferred to prevent the corrosion? (Apr 15) pH(Potential of Hydrogen). It is a measure of acidity or alkalinity of water soluble substances. pH value ( 1-14, 7-Neutral point, 1-most acidic, 14-most alkaline. Metals typically develop a passive layer in moderately alkaline (high pH) solutions, which lowers the corrosion rate as compared to acidic. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  94. 94. REVERSE OSMOSIS PLANT The plant basically consists of two phases. The first phase is a pre treatment plant.  Filtration and coagulation removes the solids and suspended particles.  Chlorination and other chemicals removes the biological organisms.  Chemical addition controls the pH and hardness. Membrane Filtration  The second phase is the membrane filtration. Sea water at high pressure is pumped to the filters. Each of the filter consists of a special membrane wrapped around an inner tube. The pressure forces the water molecules through the membranes to the inner tube. A 60 % yield of fresh water is possible in RO systems. The remaining sea water carries away the collected salts and is returned back into the sea. Increasing the number of filter modules increases the capacity of the plant. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  96. 96. NaOCL – To kill algae & Bacteria, otherwise it may harm Multi Grade Filter(MGF) MGF - To remove the large size suspended particles by using stones Acid = water mix with 3 chemicals, HCL – Remove irons by dissolving it, NaOH – Remove Acidic Salt, NaOCL – To kill algae & Bacteria Ultra Filtration Unit - Very small suspended particles are removed & then send to RO Feed tank. Dosing System = Anti Scaling Agent – Reacts with chemicals to form Scale inside the channel SMBS (sodium meta bi-sulphate) [Na2S2O5] - To remove excess HCL – pH Controlling chlorine Around 6 pH Degasser – Tower to remove carbonate ions by forming Cabon di oxide, Water from top & Air is Blown from bottom, Mixed bed in DM Plant ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  97. 97. Demineralization Plant Function – To remove dissolved salts by Ion Exchange Method (Chemical Method) Salts which make water Hard – Chloride, carbonates, Bi-carbonates, Silicates & Phosphates of Sodium, Potassium, iron, calcium & Magnesium Cation Exchange Resin – NaCl + RSO3H= RSO3 - Na+ + HCL (RSO3H – Sulfonic Acid) H2SO4, H2CO3 are also produced, Removed Na+, Water Become Acidic Anion Exchange Resin - HCL + R4NOH = H2O (R4NOH - ammonium hydroxide) Removed CL- , Acidity is avoided Mixed Bed Resins – To remove ions, (Na+ SO3 - ) Degasser – Tower to remove carbonate ions by forming Cabon di oxide, Water from top & Air is Blown from bottom. H2CO3 = H2O + CO2 , CO2 free to mix with air Carbonic Acid H2CO3 ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  98. 98. DUST COLLECTOR SYSTEM -CYCLONE SEPERATOR • Cyclone separators or simply cyclones are separation devices that use the principle of inertia to remove particulate matter from flue gases. • Cyclone separators is one of many air pollution control devices known as pre cleaners since they generally remove larger pieces of particulate matter. • Cyclone separators work much like a centrifuge, but with a continuous feed of dirty air. In a cyclone separator, dirty flue gas is fed into a chamber. The inside of the chamber creates a spiral vortex. • The lighter components of this gas have less inertia, so it is easier for them to be influenced by the vortex and travel up it. Contrarily, larger components of particulate matter have more inertia and are not as easily influenced by the vortex. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  99. 99. ELECTRO STATIC PRECIPITATOR  The medium between the electrodes is air, and due to the high negativity of negative electrodes, there may be a corona discharge surround the negative electrode rods or wire mesh. The air molecules in the field between the electrodes become ionized, and hence there will be plenty of free electrons and ions in the space  The flue gases enter into the electrostatic precipitator, dust particles in the gases collide with the free electrons available in the medium between the electrodes and the free electrons will be attached to the dust particles. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  100. 100.  As a result, the dust particles become negatively charged. Then these negatively charged particles will be attracted due to electrostatic force of the positive plates.  Consequently, the charged dust particles move towards the positive plates and deposited on positive plates. Here, the extra electron from the dust particles will be removed on positive plates, and the particles then fall due to gravitational force.  We call the positive plates as collecting plates. The flue gases after travelling through the electrostatic precipitator become almost free from ash particles and ultimately get discharged to the atmosphere through the chimney ELECTRO STATIC PRECIPITATOR ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  101. 101. PRINCIPLE OF CONDENSATION  In order to attain maximum work, according to Carnot principle, the heat must be supplied at Maximum pressure and temperature, it should be rejected at Minimum pressure and temperature.  to maintain a low back pressure on the exhaust side of the turbine so that efficiency increased.  efficiency = T1/T2 ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  102. 102. ELEMENTS OF CONDENSING PLANT  CONDENSER: In which the exhaust steam of the turbine is condensed by circulating cooling water.  CONDENSATE EXTRACTION PUMP: to remove the condensate from the condenser and feed it into the hot-well. The feed water from hot-well is further pumped to boiler. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  103. 103. ELEMENTS OF CONDENSING PLANT  COOLING TOWER: 1. The Ferro concrete made device (hyperbolic shape) in which the hot water from the condenser is cooled by rejecting heat to current of air passing in the counter direction. 2. Ring throughs are placed 8-10m above the ground level. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  104. 104. COMPARISION Jet condensers 1. Steam and water comes in direct contact. 2. Condensation is due to mixing of coolant. 3. Condensate is not fit for use as boiler feed until the treated cooling water is supplied. 4. It is cheap. Does not affect plant efficiency. 5. Maintenance cost is low. 6. Vacuum created is up to 600 mm of Hg.{1bar=760mm of Hg} Surface condensers Steam and water does not come in direct contact. Condensation is due to heat transfer by conduction and convection. Condensate is fit for reuse as boiler feed. It is costly. Improves the plant efficiency. Maintenance cost is high. Vacuum created is up to 730 mm of Hg. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  105. 105. LOW LEVEL PARALLEL FLOW JET INJECTOR  The mixture of condensate, coolant and air are extracted with the help of wet air pump.  Vacuum created in the condenser limits up to 600 mm of Hg. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  106. 106. HIGH LEVEL JET CONEDNSER/ BAROMETRIC JET CONDENSER  It is also called Barometric jet condenser since it is placed above the atmospheric pressure equivalent to 10.33 m of water pressure.  Condensate extraction pump is not required because tail pipe has incorporated in place of it.ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  107. 107. EJECTOR JET CONDENSER  The cooling water enters the top of the condenser at least under a head of 6m of water pressure with the help of centrifugal pump.  This system is simple, reliable and cheap.  Disadvantage of mixing of condensate with the coolant. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  108. 108. SURFACE CONDENSERS ARE OF TWO TYPES  SURFACE CONDENSERS In this steam flows outside the network of tubes and water flows inside the tubes.  EVAPORATIVE CONDENSERS In this condenser shell is omitted. The steam passes through condenser tubes, the water is sprayed while the air passes upward outside the tube. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  109. 109. CLASSIFICATION OF SURFACE CONDENSERS  The number of water passes: 1. Single pass 2. Multipass  The direction of condensate flow and tube arrangement: 1. Down flow condenser 2. Central flow condenser ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  110. 110. DOUBLE PASS SURFACE CONDENSER  It consist of air tight cast iron cylindrical shell.  If cooling water is impure, condenser tubes are made up of red brass. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  111. 111. DOWN FLOW SURFACE CONDENSER  This condenser employs two separate pumps for the extraction of condensate and the air.  Baffles(flow directing vane) are provided so that the air is cooled to the minimum temperature before it is extracted.  The specific volume of cooled air reduces, thereby, reduces the pump capacity to about 50%. Therefore, it also reduces the energy consumption fro running the air pump.ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  113. 113. CENTRAL FLOW SURFACE CONDENSER  Air extraction pump is located at the centre of the condenser tubes.  Condensate is extracted from the bottom of the condenser with the help of condensate extraction pump.  Provides the better contact of steam. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  114. 114. EVAPORATIVE CONDENSER  The exhaust steam is passed through the series of gilled tubes called condenser coils.  Thin film of cooling water trickles over these tubes continuously from water nozzles.  During the condensation of steam, this thin film of water is evaporated and the remainder water is collected in the water tank.  The condensate is extracted with the help of wet air pump.  The air passing over the tubes carries the evaporated water in the form of vapour and it is removed with the help of induced draft fan installed at the top. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  115. 115. MERITS AND DEMERITS OF SURFACE CONDENSERS  MERITS 1. No mixing of cooling water and steam, hence the condensate directly pumped into the boiler. 2. Any kind of feed water can be used. 3. Develops high vacuum, therefore suitable for large power plants. 4. System is more efficient.  DEMERITS 1. Require large quantity of cooling water. 2. System is complicated, costly and requires high maintenance cost. 3. Require large floor space since it is bulky. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  116. 116. REQUIREMENTS OF A MODERN SURFACE CONDENSER  The exhaust steam entering the condenser should be evenly distributed over the whole cooling surface of the condenser vessel with minimum pressure loss.  The amount of cooling water being circulated in the surface condenser should be regulated that the temperature of cooling water leaving the condenser is equivalent to saturation temperature of steam corresponding to steam pressure. This will prevent under cooling of condensate.  The deposition of dirt on the outer surface of tubes in surface condensers need to be prevented. Passing the cooling water through the tubes and allowing the steam to flow over the tubes makes this happen.  There should be no leakage of air into the condenser because presence of air destroys the vacuum in the condenser and thus reduces the work obtained per kg of steam. If there is any leakage of air into the condenser air extraction pump need to be used to remove air as soon as possible. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  117. 117. STEAM RATE The capacity of the plant is expressed in terms of steam rate or Specific Steam Consumption(SSC). Rate of steam flow required to produce unit shaft output. Steam rate = mass of steam/work output in kg/k.Wh Steam rate = 3600.ms / WT Ms – steam flow rate in kg/s WT – turbine work, kW ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
  118. 118. HEAT RATE  It is defined as the heat input needed to produce one unit of power output  It indicates the amount required to generate one unit electricity  Heat rate = heat supplied / work output  Heat rate = 3600.Q1 / WT  Q- Kg/s  W-Kw ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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  120. 120. Reason out why cogeneration is quite viable in sugar industries compared to that in other industries. (Nov 17) Sugar production is a major Agro-Based industry in India. It generates various solid wastes sugar cane trash, bagasse; press mud & bagasse fly ash. Bagasse is a fibrous residue obtained after juice extraction which contains 45- 50% moisture & 1% ash. Its calorific value is 8022 KJ/kg. It is commonly used as a fuel in boilers to generate steam & electricity through cogeneration. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET
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