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Field Performance
Evaluation of ORC
Geothermal Power
Plants Using Radial
Outflow Turbines
1
F E D E R I C O M I N O L I P r o p o s a l E n g i n e e r
A U T H O R S L . Z a n e l l a t o , E . M a c c h i ,
M . A s t o l f i , D . R i z z i
2
SUMMARY
› EXERGY’s Radial Outflow Turbine technology
› Greeneco power plant description
› Akca power plant descritpion
› Experimental measurement campaign
› Methodology: error minimization process
› Results: Greeneco and Akca turbine efficiency
› Conclusions
THE RADIAL OUTFLOW TURBINE
3 3D cross section of the radial outflow turbine
THE RADIAL OUTFLOW TURBINE
Why choose a centrifugal (outflow) turbine to expand a fluid?
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› Excellent Match between volumetric flow
and the cross section
› Straight blades
› Easy maintenance: mechanical group fast
substitution
› Lower vibration
Only the Radial Outflow Turbine allows multiple pressure
admissions on a single disk.
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G R E E N E C O
E N E R J I ,
S A R A Y K Ö Y 1 ,
T U R K E Y
Y E A R : 2 0 1 5
A P P L I C A T I O N : G E O
P O W E R : 1 2 M W
GREENECO
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› Steam = 20 tons/hr
› Brine = 1350 tons/hr
› T source = 135°C
› 2 pressure levels,2 turbines
› Water cooled (20°C)
› Isopentane
› 12 MW gross
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A K Ç A E N E R J I
D E N I Z L I ,
T U R K E Y
Y E A R : 2 0 1 4
A P P L I C A T I O N : G E O
P O W E R : 4 M W
AKCA
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› Steam = 8.8 tons/hr
› Brine = 691 tons/hr
› T source = 105°C
› 2 pressure levels, 1 turbine
› Water cooled (18°C)
› Refrigerant
› 3.9 MW gross
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EXPERIMENTAL MEASUREMENTS
› Integration of higher precision
instrumentation
› Analysis on 20 minutes of instruments data
every 5 seconds
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METHODOLOGY
BUT….Turbine efficiency is very sensitive to outlet temperature
(2°C means 8%)
Increase the consistency of the analysis
› Turbine inlet conditions verified with RefProp
› Turbine flow rate is verified with factory measurement on
turbine geometry
› Heat and mass balances at each component
› Gross power output check
ITERATIVE ERROR MINIMIZATION PROCESS
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RESULTS
› GREENECO: brine mass flow rates converge with turbine outlet
temperature inside instrument accuracy (+/- 0.25°C)
› AKCA: turbine efficiency and LP evaporator pinch point converge
with turbine outlet temperature between the 2 measured values
› η Greeneco HP = 85.5 %
› η Greeneco LP = 88.4 %
› η Akca = 92.0 %
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CONCLUSION
› Direct calculation of turbine efficiency from measurements is
affected by uncertainty even for high precision instrumentation
› Consistency of measured data checked with heat and mass
equations and energy output
› Exergy turbines result in a very high efficiency
› η Greeneco HP = 85.5 %
› η Greeneco LP = 88.4 %
› η Akca (patented 2 pressure levels on a single disk)= 92.0 %
H E A D O F F I C E
Via degli Agresti, 6
40123 Bologna (BO) ITALY
Via Santa Rita, 14
21057 Olgiate Olona (VA) ITALY
Tel +39 0331 18 17 711
Fax +39 0331 18 17 731
O P E R A T I N G H E A D Q U A R T E R S
E X E R G Y - O R C . C O M
I N F O @ E X E R G Y . I T
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