geothermal power plant projects in central america - Orkustofnun

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TABLE 3: Parameters and boundary conditions of the geothermal power plant modelsSystemParameterValuesUnit Low HighGeothermalReservoirPowerPlantGeothermal fluidMaximum well head pressure kPa 100.0 3500.0Non condensable gases in well mass flow % 0.5 0.5Temperature of resource °C 100.0 340.0EfficienciesTurbine isentropic efficiency % 0.9 0.9Compressor isentropic efficiency % 0.7 0.7Pumps isentropic efficiency % 0.7 0.7Fan efficiency % 0.7 0.7Cooling systemOperating condenser pressure - Flash units kPa 10.0 10.0Operating condenser pressure - ORC units kPa 140.0 600.0Minimum pinch temperature in condenser °C 5.0 5.0Increasing temperature of cooling water °C 12.0 12.0Air dry temperature °C 28.0 28.0Relative humidity % 0.8 0.8• Well production is not dependent on wellhead pressure• Evaporation of the cooling water is neglected• The fluid chemistry is neglected• Pressure losses in pipelines and other equipment are neglected4.2.2 Design variables and constraintsBasic components of an optimization problem involve an objective function expressing the main aimof the model which has to be minimized or maximized, a set of unknowns or variables which controlthe value of the objective function, and a set of constraints that allow unknowns to take on certainvalues but exclude others (Kumar, 2010).In this analysis, the objective function is net power output per mass flow of geothermal fluid. Table 4shows the optimization variables and constraints selected for the energy conversion systems. Theoptimization variables are independent design variables of each system. For SF and DF, separatorpressure is considered the design variable, and for ORC the boiler pressure is used.TABLE 4: Design variables and constraintsPower cycle Variable ContraintSF Separator pressure Turbine exhaust dryness ≥ 0.85HP Separator presure Turbine exhaust dryness ≥ 0.85DFTurbine exhaust dryness ≥ 0.85LP Separator presurePressure ≥ 75 kPaORCBoiler PressurePinch at boiler ≥ 5°CPinch at recuperator ≥ 5°C4.3 ResultsIn this section SF, DF and ORC power plant cycles are evaluated for different resource temperatures(°C). The results present the optimum specific net power output (kW/kg/s) and the optimum working23
pressures (kPa) in the separator for SF and DF cases and in the boiler for the ORC case. In order tosimplify reading from the graphs, the optimum net power output (kW) for a unit mass flow rate isused; the total power output can be obtained for each specific case simply by multiplying this by theactual mass flow rate in kg/s.4.3.1 Single flashThe selection of the separatorpressure has an important effect onthe overall plant performance interms of power output (Figure 19).High separator pressures result inhigher working potential steam atthe turbine inlet, a lower quality ofsteam in the turbine exhaust andhigher injection temperature.Lower separator pressures increasethe mixture quality in the separator,which means that more steam canbe produced, but the specificavailable energy of the steam flowwould decline.The optimization routine isrelatively simple since there is onlyone optimization variable and it canbe determined by varying the valueof the wellhead pressure to locatethe power output maximum(Karlsdóttir, 2008). The results ofthe optimization process arepresented in Figure 20 as theoptimum specific net output and theseparator pressure (kPa) as afunction of the resourcestemperature. The specific net poweroutput is directly proportional tothe resource temperature. Theseparator pressure increases for aresource temperature ranging from160 to 280°C; for higher resourcevalues it is constant as the constraints of the steam quality of the turbine exhaust cannot be lower than0.85, as seen in Figure 20.4.3.2 Double flashSpecific power output [ kW/kg/s ]Specific net power output [ kW/kg/s ]3002502001501005030025020015010000160 180 200 220 240 260 280 300 320 340Resource temperature [°C]50Specific net power outputSeparator pressureFIGURE 4: Specific net power output and separatorpressure of SF cycleSpecific net power outputSteam quality at turbine output00.70160 180 200 220 240 260 280 300 320 340Resource temperature [ °C ]In the optimization process of a DF cycle, the maximum power output is gotten by adjusting the valueof the high-pressure (HP) and low-pressure (LP) separators. Also, in a DF cycle, as in a SF cycle, thesteam quality of the turbine exhaust is a constraint in the optimization process, in this case for twostations at the exhaust of LP and HP turbines (Figure 22).Figure 21 shows the optimum specific net output and pressure separation for different resourcetemperatures. The specific net power output and the optimum pressure value of the HP separator aredirectly proportional to the temperature resource. In the DF system, as shown in Table 3, themaximum well head pressure was set at 3500 kPa, corresponding to the HP separator pressure at340°C. Where limits for the maximum well head pressure are set lower, the pressure increases until it8007006005004003002001001.000.950.900.850.800.75FIGURE 4: Specific net power output and steam qualityof turbine output of SF cycleSeparator pressure [ kPa ]Steam quality [ - ]24
Page 1 and 2: GEOTHERMAL TRAINING PROGRAMMEHot sp
Page 3 and 4: This MSc thesis has also been publi
Page 5 and 6: ACKNOWLEDGEMENTSMy gratitude to the
Page 7 and 8: TABLE OF CONTENTSPage1. INTRODUCTIO
Page 9 and 10: PageAPPENDIX A: FINANCIAL MODEL ...
Page 12 and 13: 1. INTRODUCTIONRecent research on r
Page 14 and 15: 2. CENTRAL AMERICAN DATA2.1 Power p
Page 16 and 17: 2.2.3 HondurasThe Honduran electric
Page 18 and 19: NET INJECTION BY SOURCE (2010)INSTA
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Page 22 and 23: annual temperature ranges from 17 t
Page 24 and 25: egional reconnaissance in 1981ident
Page 26 and 27: 4. GEOTHERMAL ELECTRICAL POWER ASSE
Page 28 and 29: The net contribution of that power
Page 30 and 31: Introducing , = , and , = ,
Page 32 and 33: 9ProductionWellBoiler5Turbine~1046P
Page 36 and 37: eaches the maximum limit, and for h
Page 38 and 39: 160180140160tc vap[i], th vap[i]120
Page 40 and 41: average results, and combining them
Page 42 and 43: The base cost ( ) can be calculate
Page 44 and 45: calculation for another separator c
Page 46 and 47: mass flow rate (kg/s) on the plant
Page 48 and 49: Table 11 shows a summary of costs f
Page 50 and 51: 5.6.4 Comparison of capital costs b
Page 52 and 53: 6. FINANCIAL FEASIBILITY ASSESSMENT
Page 54 and 55: 6.2 Model structureThe financial fe
Page 56 and 57: CCF = EBITDA − ∆Working Capital
Page 58 and 59: Interest on loansFleischmann (2007)
Page 60 and 61: IRR30%25%IRR CapitalIRR Equity20%Si
Page 62 and 63: FIGURE 42: Allocation of funds for:
Page 64 and 65: 340IRR Free Cash Flow to Equity [ %
Page 66 and 67: flash technology is between 0.3 and
Page 68 and 69: Energy Price Availability Factor O&
Page 70 and 71: FIGURE 50: Density and cumulative p
Page 72 and 73: In Chapter 6, Figure 44 illustrated
Page 74 and 75: The internal rate of return is offs
Page 76 and 77: Cengel, Y. and Tuner, R., 2005: Fun
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Page 80 and 81: Salmon, J., Meurice, J., Wobus, N.,
Page 82 and 83: APPENDIX A: SUMMARY OF FINANCIAL MO
Page 84 and 85:
APPENDIX C: INVESTMENT AND FINANCIN
Page 86 and 87:
APPENDIX E: BALANCE SHEETBALANCE SH
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