Energy Conversion Technology 2 - Binary power plant presentation

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  • Optimal Design of Binary Cycle Power Plants for water-dominated, medium-temperature

    geothermal fields

    Energy Conversion Technologies 2

    Riccardo Pagotto

  • Outline

    ! The Geothermal Energy and Geological settings

    ! Binary Cycle Power Plant

    ! Analytical aspect: merit parameters of a Binary Cycle Power Plant

    ! Performance evaluations

  • Geothermal Energy and Geological setting

    Source: geo-energy.org

    ! Geothermal gradient (crust)

    Extensive settings 50-60C/km

    Compressive settings 15-20C/km

    Avg crust 30C/km

    1

    Source: Geophysic Booklet, Claudia Pasquero (2011)

    3

    2 Source: geo-energy.org

    Source: geo-energy.org

    ! Heat Flux

    Avg 87 mW/km2

  • BCPP

    ! BCPP

    Heat Recovery Cycle (HRC)

    Recovery Heat Exchanger (RHE)

    Cooling System (CS)

    ! Tempatures range

    Tgeo 110160 C

    Trej 70100 C

    Tcond 3040 C

    Source:Optimal Design of Binary Cycle Power Plantsfor water-dominated,medium-temperature geothermal fields; A.Franco, M.Villani (2009)

    ! Total installed power

    worldwide 700 Mwe

    Plant size 500 kW 10 MW

    Efficiency 7 12%

    Source:Indian Istitute of Technology

    HRC

    RHE

    CS

  • 2

    Source:learnthermo.com

    3

    Source:learnthermo.com

    Source:Optimal Design of Binary Cycle Power Plantsfor water-dominated, medium-temperature geothermal fields; A.Franco, M.Villani (2009)

    1-BCPP op/mal design ! BCPP purpose

    is minimizing

    m [kg/s]

    [kg/MJ]

  • Analytical Aspect: merit parameters of a BCPP

    Q0 = Heat Flow Rate [W]

    EX = Energy Flow [W]

    EX0 = Energy Flow [W]

    Reference state, T0 = 25C Source:Optimal Design of Binary Cycle Power Plantsfor water-dominated,medium-temperature geothermal fields; A.Franco, M.Villani (2009)

    1-First Law Efficiency

    1

    2

    2-Second Law Efficiency

    2

  • = specific brine consumption [kg/MJ]

    I = Energy Loss Flow [W] = energy loss into steam turbine, recovery heat exchanger, condenser and rejected

    Source:Optimal Design of Binary Cycle Power Plantsfor water-dominated,medium-temperature geothermal fields; A.Franco, M.Villani (2009)

    Thermodinamic phase diagram Synthetic refrigerant:

    R134a, R401a, R152a

    Hydrocarbons:

    Isobutane, n-pentane

  • Performance Evaluation

    Source:Optimal Design of Binary Cycle Power Plantsfor water-dominated,medium-temperature geothermal fields; A.Franco, M.Villani (2009)

    1- BCPP, Poten/al and Limits (Tgeo-Trej C)

    1

    2

    2- BCPP, Poten/al and Limits (Tgeo-Trej-Tcond C)

    ! Tested fluids

    Hydrocarbons: Isobutane, n-pentane

    Syn. refrigerants: R134a, R152a

    Mixture: R401A, R407C ! Diagram n1

    Hydrocarbons ! small T

    R152a ! large T

    ! Diagram n2

    Hydrocarbons ! small T

    R152a ! large T

    ! Temperature system 160-70-30 (C)

    First Law Efficiency = 12%

    Second Law Efficiency = 45%

  • Conclusion ! Advantages

    Binary plants with dry cooling systems represent a sustainable way to exploit low-temperature, water-dominated geothermal fields

    No additional water is required and emissions of chemical pollutants (Hg + As) and greenhouse gases are close to zero

    Best results obtained with Isobutane and R152a

    ! Disadvantages

    Geological aspects (depth of the reservoir ! Tgeo, chemical composition of the geofluid and rock permability)

    Temperatures variation ! efficiency variation

    Gross Power absorbed by BCPP 10-12%

    Quite high costs 2000-4000 /kW ! limited distibution

    Source:Optimal Design of Binary Cycle Power Plantsfor water-dominated,medium-temperature geothermal fields; A.Franco, M.Villani (2009)

  • Assessment of the review

    Positive: The article gives an exhaustive background on Binary Cycle Power Plant

    Completeness: The article includes a general overview, but also a thorough mathematical analysis and a technical description of the power plant

    Correctness: The paragraphs are well set up and related, in order to provide a better

    understanding of the issue

  • Thank you for attention!

    Youre

    welcooome!!!

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