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?

4

› 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.

5

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

6

› 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

7

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

8

› 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

9

EXPERIMENTAL MEASUREMENTS

› Integration of higher precision

instrumentation

› Analysis on 20 minutes of instruments data

every 5 seconds

10

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

11

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 %

12

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

13

op

era

tin

g

hq