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Unit 1-Thermal Power Plants

Unit 1-Thermal Power Plants. Steam power plant Layout Boilers Pulverized coal burners Fluidized bed combustion. Power generating units are mega projects Require huge capital investment Require natural resources like, fossil fuels Large amount of water Changes the local eco system

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Unit 1-Thermal Power Plants

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  1. Unit 1-Thermal Power Plants • Steam power plant • Layout • Boilers • Pulverized coal burners • Fluidized bed combustion

  2. Power generating units are mega projects Require huge capital investment Require natural resources like, fossil fuels Large amount of water Changes the local eco system Huge Impacts on the Environment and Health

  3. Understanding Coal fired Thermal Power plants

  4. Understanding Coal fired Thermal Power plants

  5. Coal Mining • Surface Mining • Strip Mining • Underground Mining

  6. Understanding Coal fired Thermal Power plants Air Quality Around the coal based plants the ambient concentrations of Sulphur Dioxide, Oxides of Nitrogen and SPM are high. Epidemiological Studies have shown that of the area surrounding coal based thermal plants, population living within a 2 -5 km radius of the plant suffers from respiratory disorders . Two other gases, carbon dioxide and ozone are emitted. The high amount of carbon dioxide emission from thermal power plants contribute to global warming leading to climate change is significant Ground level ozone, which is formed due to photolytic reactions of NOx and its impacts are under study

  7. Understanding Coal Fired Thermal Power Plants Fly ash contains a toxic brew of dangerous chemicals and is the largest contributor to mercury pollution

  8. Understanding Coal fired Thermal Power plants Composition of Fly ash It contains as main chemical components SiO2 (51.4 wt%), Al2O3 (22.1 wt%) and Fe2O3 (17.2 wt%; ignited weight basis). As commonly observed, many toxic elements and heavy metals are highly enriched in the fly ash relative to the original coal. For example, considerable amounts of Be (16.4 ppm), Cu (106 ppm), Zn (578 ppm), As (40.4 ppm), Cd (2.6 ppm), Hg (18 ppm), Pb (71 ppm), and U (21.8 ppm) is found in Fly ash.

  9. Understanding Coal fired Thermal Power plants Water slurry is used to take the ash from the power plant to the ash pond for disposal.  Water slowly seeps into the ground while carrying with it the ash leach ate. Water may contain harmful heavy metals like boron, which have a tendency to leach out over a period of time.  When fly ash comes into contact with water, leaches into groundwater supplies which get polluted and unsuitable for domestic use.  The release of ash pond decant into the local water bodies- water dries up, dust nuisance, increases turbidity, decreases primary productivity, affects fishes and other aquatic biota

  10. Coal Power Plant Operation • Steam Turbine Generator • Is a series of steam turbines interconnected to each other and then a generator • Steam Condenser • Steam enters from the turbine generator and is pumped into the bottom of the condenser, where pumps recycle the condensed steam from the feedwater • Stack • Releases process emissions.

  11. Introduction What is a Boiler? • Vessel that heats water to become hot water or steam • At atmospheric pressure water volume increases 1,600 times • Hot water or steam used to transfer heat to a process

  12. Introduction STEAM TO PROCESS VENT EXHAUST GAS STACK DEAERATOR PUMPS ECO-NOMI-ZER BOILER VENT BURNER WATER SOURCE BLOW DOWN SEPARATOR FUEL BRINE CHEMICAL FEED SOFTENERS Figure: Schematic overview of a boiler room

  13. Types of Boilers • Fire Tube Boiler • Water Tube Boiler • Packaged Boiler • Fluidized Bed (FBC) Boiler • Stoker Fired Boiler • Pulverized Fuel Boiler • Waste Heat Boiler • Thermic Fluid Heater (not a boiler!)

  14. Type of Boilers 1. Fire Tube Boiler • Relatively small steam capacities (12,000 kg/hour) • Low to medium steam pressures (18 kg/cm2) • Operates with oil, gas or solid fuels

  15. Type of Boilers 2. Water Tube Boiler • Used for high steam demand and pressure requirements • Capacity range of 4,500 – 120,000 kg/hour • Combustion efficiency enhanced by induced draft provisions • Lower tolerance for water quality and needs water treatment plant

  16. To Chimney Oil Burner Type of Boilers 3. Packaged Boiler • Comes in complete package • Features • High heat transfer • Faster evaporation • Good convective heat transfer • Good combustion efficiency • High thermal efficiency • Classified based on number of passes

  17. Type of Boilers 4. Fluidized Bed Combustion (FBC) Boiler • Particles (e.g. sand) are suspended in high velocity air stream: bubbling fluidized bed • Combustion at 840° – 950° C • Capacity range 0,5 T/hr to 100 T/hr • Fuels: coal, washery rejects, rice husk, bagasse and agricultural wastes • Benefits: compactness, fuel flexibility, higher combustion efficiency, reduced SOx & NOx

  18. Type of Boilers • 4a. Atmospheric Fluidized Bed Combustion (AFBC) Boiler • Most common FBC boiler that uses preheated atmospheric air as fluidization and combustion air • 4b. Pressurized Fluidized Bed Combustion (PFBC) Boiler • Compressor supplies the forced draft and combustor is a pressure vessel • Used for cogeneration or combined cycle power generation

  19. Type of Boilers 4c. Atmospheric Circulating Fluidized Bed Combustion (CFBC) Boiler • Solids lifted from bed, rise, return to bed • Steam generation in convection section • Benefits: more economical, better space utilization and efficient combustion

  20. Type of Boilers • 5. Stoke Fired Boilers • a) Spreader stokers • Coal is first burnt in suspension then in coal bed • Flexibility to meet load fluctuations • Favored in many industrial applications

  21. Type of Boilers 5. Stoke Fired Boilers b) Chain-grate or traveling-grate stoker • Coal is burnt on moving steel grate • Coal gate controls coal feeding rate • Uniform coal size for complete combustion

  22. Type of Boilers 6. Pulverized Fuel Boiler • Pulverized coal powder blown with combustion air into boiler through burner nozzles • Combustion temperature at 1300 -1700 °C • Benefits: varying coal quality coal, quick response to load changes and high pre-heat air temperatures Tangential firing

  23. Control panel Insulated outer wall Exhaust Blower motor unit Fuel oil filter Type of Boilers 3. Heat transfer through heat exchanged 8. Thermic Fluid Heater User equipment 2. Circulated to user equipment 4. Fluid returned to heater 1. Thermic fluid heated in the heater (Energy Machine India)

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