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Steam Generation Efficiency

Steam Generation Efficiency. Efficiency Definition Radiation and Convection losses – Shell losses Blowdown losses Stack losses. Steam Generation Efficiency. Efficiency Definition Radiation and Convection losses – Shell losses Blowdown losses Stack losses. Classic Boiler Efficiency.

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Steam Generation Efficiency

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

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

  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

  4. Operating Cost • Boiler fired with natural gas which has a higher heating value of 23,311 Btu/lbm • HHV is 1,000 Btu/sft³ • Steam conditions: 400 psig, 700°F • Output: 100,000 lbm/hr (steady) • Rating: 120,000 lbm/hr (maximum continuous) • Feedwater: 600 psig, 242°F • Fuel supply: 149,000 sft³/hr (2,480 sft³/min) • Fuel cost: $10.00/10⁶Btu ($10.0/10³sft³) • Determine the operating cost

  5. Boiler Operating Cost Answer: Appendix

  6. Steam Cost Indicator Answer: Appendix

  7. Typical Boiler Efficiency • A typical boiler will have an efficiency of ----?

  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

  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

  10. Efficiency Example Steam Properties

  11. Direct (Classic) Efficiency Calculation This evaluation is also known as direct efficiency

  12. Efficiency Calculation Why is the efficiency not 100%?

  13. Efficiency Calculation Why is the efficiency not 100%?losses Answer: Appendix

  14. Boiler Losses • Identify the Boiler losses Exhaust Gases Feedwater Inlet Steam Outlet Fuel and Air

  15. Boiler Losses Combustion and Temperature • Identify the Boiler losses Feedwater Inlet Steam Outlet Exhaust Gases Radiation and Convection Fly Ash Blowdown Fuel and Air Bottom Ash Answer: Appendix

  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

  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 PTC–4 ) • Fuel efficiency (the same as the classic equation) • Gross efficiency (includes auxiliary input streams) • ASME PTC–4 describes two investigation methods • Input/output (direct method) • Energy balance (indirect method)

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