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Download Steam Generation Efficiency Efficiency Definition Radiation and Convection losses – Shell losses Blowdown losses Stack losses

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  • Slide 1
  • Steam Generation Efficiency Efficiency Definition Radiation and Convection losses Shell losses Blowdown losses Stack losses
  • Slide 2
  • Steam Generation Efficiency Efficiency Definition Radiation and Convection losses Shell losses Blowdown losses Stack losses
  • Slide 3
  • 3 Classic Boiler Efficiency Steam generating unit efficiency is defined as the heat absorbed by the steam divided by the energy input with the fuel
  • Slide 4
  • 4 Operating Cost Boiler fired with natural gas which has a higher heating value of 23,311 Btu/lbm HHV is 1,000 Btu/sft Steam conditions: 400 psig, 700F Output: 100,000 lbm/hr (steady) Rating: 120,000 lbm/hr (maximum continuous) Feedwater: 600 psig, 242F Fuel supply: 149,000 sft /hr (2,480 sft /min) Fuel cost: $10.00/10 Btu ($10.0/10 sft ) Determine the operating cost
  • Slide 5
  • 5 Boiler Operating Cost Answer: Appendix
  • Slide 6
  • 6 Steam Cost Indicator Answer: Appendix
  • Slide 7
  • 7 Typical Boiler Efficiency A typical boiler will have an efficiency of ----?
  • Slide 8
  • 8 Typical Boiler Efficiency A typical boiler will have an efficiency of ----? 75% to 82% to 90% Wood Natural Gas Oil and Coal Efficiency is dependent on the type of fuel and the installed equipment. Answer: Appendix
  • Slide 9
  • 9 Boiler Efficiency For the example boiler determine the steam generation efficiency. This is also called Boiler efficiency First law efficiency Fuel to steam energy conversion efficiency
  • Slide 10
  • 10 Efficiency Example Steam Properties Properties LocationTempPSpecificEnthalpyEntropyQualityP [F][psia]Volume[Btu/lbm][Btu/lbmR][%][psig] [ft /lbm] Boiler outlet700414.71.589461,361.881.63527****400 Saturated vapor448414.71.120251,204.621.46906100.0400 Saturated liquid448414.70.01939428.040.625610.0400 Deaerator storage23924.70.01692207.740.352330.010 Feed pump exit242614.70.01694210.420.356150.0600 Condensate18014.70.01650147.910.262890.00 Makeup water7514.70.0160543.040.083970.00
  • Slide 11
  • 11 Direct (Classic) Efficiency Calculation This evaluation is also known as direct efficiency
  • Slide 12
  • 12 Efficiency Calculation Why is the efficiency not 100%?
  • Slide 13
  • 13 Efficiency Calculation Answer: Appendix Why is the efficiency not 100%? losses
  • Slide 14
  • 14 Boiler Losses Identify the Boiler losses Steam Outlet Feedwater Inlet Fuel and Air Exhaust Gases
  • Slide 15
  • 15 Boiler Losses Identify the Boiler losses Steam Outlet Feedwater Inlet Fuel and Air Exhaust Gases Combustion and Temperature Fly Ash Bottom Ash Blowdown Radiation and Convection Answer: Appendix
  • Slide 16
  • 16 Indirect Efficiency Boiler efficiency can also be determined in an indirect manner by determining the magnitude of the losses Primary losses are typically Shell loss Blowdown loss Stack loss
  • Slide 17
  • 17 ASME Boiler Efficiency American Society of Mechanical Engineers (ASME) has established a comprehensive testing standard for fired boilers ASME Power Test Code 4 (ASME PTC4 ) Fuel efficiency (the same as the classic equation) Gross efficiency (includes auxiliary input streams) ASME PTC4 describes two investigation methods Input/output (direct method) Energy balance (indirect method)

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