EthosEnergy performed a thermodynamic and mechanical analysis of the existing unit and assessed what improvements could be made. From this analysis the turbine diaphragms and blades for three of the six stages were redesigned by reducing the blade height. Since new blades and diaphragms were required, EthosEnergy changed the design to an integral covered configuration with replaceable tip spill strips in the diaphragm. This change eliminated one of the biggest issues on geothermal steam turbine blades which is tenon erosion. The integral cover design eliminates the tenon and allows for improved sealing.
The analysis indicated that six stages were still the best design but the nozzle mouth heights had to be reduced on stages 4 & 5. Even though the steam specific volume went up, the flow required to make the target output of 32.2 MW was lower than the original design volume flow. Nozzle and blade flow passing areas were also changed to account for the change in total volume flow and to distribute the loading optimally across each stage.