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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

Steam Generation Efficiency

Efficiency Definition

Radiation and Convection losses – Shell losses

Blowdown losses

Stack losses


Steam generation efficiency1

Steam Generation Efficiency

Efficiency Definition

Radiation and Convection losses – Shell losses

Blowdown losses

Stack losses


Classic boiler efficiency
Classic Boiler Efficiency

  • Steam generating unit efficiency is defined as the heat absorbed by the steam divided by the energy input with the fuel


Operating cost
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


Boiler operating cost
Boiler Operating Cost

Answer: Appendix


Steam cost indicator
Steam Cost Indicator

Answer: Appendix


Typical boiler efficiency
Typical Boiler Efficiency

  • A typical boiler will have an efficiency of ----?


Typical boiler efficiency1
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


Boiler efficiency
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



Direct classic efficiency calculation
Direct (Classic) Efficiency Calculation

This evaluation is also known as direct efficiency


Efficiency calculation
Efficiency Calculation

Why is the efficiency not 100%?


Efficiency calculation1
Efficiency Calculation

Why is the efficiency not 100%?losses

Answer: Appendix


Boiler losses
Boiler Losses

  • Identify the Boiler losses

Exhaust Gases

Feedwater Inlet

Steam Outlet

Fuel and Air


Boiler losses1
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


Indirect efficiency
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


Asme boiler efficiency
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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