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ORGANIC RANKINE CYCLE FOR 
GEOTHERMAL

Geothermal resources are one of the most secure and stable renewable sources of electrical energy production. In particular the direct use of geothermal has seen a massive 45% growth since 2010, with installed capacity now reaching 70,330 MWth spread across 82 countries.

The worldwide hunt for new sources of green energy has created a promising market for electrical power production from geothermal sources at medium-low temperatures. The binary cycle with organic fluid (the ORC system) has proven to be the best power generating solution in these cases.

EXERGY develop, design and manufacture the most efficient Organic Rankine Cycle (ORC) geothermal binary power plants, using the innovative and pioneering Radial Outflow Turbine (ROT) technology.

ADVANTAGES

Based on the ORC Radial Outflow Turbine technology, EXERGY offer the following advantages (accommodating for multiple stage single disk and possible multiple admissions on a single disk):

  • Superior efficiency (up to 6% additional efficiencies over the axial turbine)
  • Better exploitation of high enthalpy resources (up to 8 stages)
  • Very cost effective, multiple pressure level plant with single turbine disk. Our innovative

Radial Outflow Turbine design enables us to offer 2 pressure levels with a single expander, giving up to 20% more power than competitors.

  • Less maintenance due to single disk and lower vibration
  • Extreme flexibility for changing geothermal fluid conditions, in terms of flow, temperatures and constituents, due to a higher number of stages
  • Suitable for low temperature heat sources, as low as 90° C


APPLICATIONS
  • Low/medium enthalpy applications
  • Small steam applications
  • Mixed steam and brine applications combined cycle application (flash and binary)
  • From standard 100kW packages up to 50MW tailored design plants
  • Well-head generation

 

THE MULTI PRESSURE RADIAL OUTFLOW TURBINE SOLUTION 


Binary geothermal power plants have the possibility to be developed as multi pressure level cycle systems. This cycle configuration offers a significant increase in the power output and in the cycle efficiency. Technologically advanced multi pressure level geothermal binary systems traditionally available on the market require at least one turbine per pressure level, to expand the organic vapor, and these turbines are normally installed with an overhung configuration. The EXERGY Radial Outflow Turbine, thanks to its unique single disk and multi-stage configuration, allows multiple pressure level cycles to be expanded on a single disk turbine. 

The geothermal fluid is passed through the first sequence of HIGH pressure heat exchangers, passing enthalpy to the organic fluid. This organic fluid vaporizes and is passed through the HIGH pressure  turbine Inlet. Then the geothermal fluid  is passed through the second sequence of LOW pressure heat exchangers, vaporizing the organic fluid, which is then passed through the LOW pressure turbine Inlet. The EXERGY Radial Outflow Turbine (ROT), fed by HIGH and LOW pressure organic fluids, drives a generator to produce electrical power. The geothermal fluid is then re-injected back into the ground and the process can restart.

 
 

EFFICIENCY GRAPH