Siemens Energy has launched its new steam turbine for
geothermal power plants. With a rating of up to 60 mw,
the new SST-400 GEO steam turbine for geothermal
applications combines the proven casing and turbine generator
package (gearbox, generator and base frame) of the
Siemens SST-400 steam turbine with the steam path
technologies developed, tested and applied by the steam
turbine service provider TurboCare. The SST-400 GEO steam
turbine can be deployed in geothermal power plants with
different thermal fluids, a release from Siemens said.
At the end of 2010, the global installed power generating
capacity of geothermal power plants was more than 11
gigawatts (GW). The U.S. currently leads the world with an
installed geothermal capacity of 3.1 GW, followed by the
Philippines with an installed geothermal capacity of
approximately 1.9 GW, and Indonesia with 1.2 GW. There also
exists the potential for the utilization of geothermal energy for
power generation in East Africa, Central America, Chile,
Russia, Italy, Iceland and Turkey. Based on a study conducted
by IHS Emerging Energy Research, the installed capacity of
geothermal power is predicted to nearly triple worldwide to
approximately 31 GW by 2020, the release noted.
The sites for geothermal plants vary significantly in terms
of thermal fluid mass flow, temperature, pressure, pH and the
fraction of minerals and gases such as hydrogen sulfide in the
thermal fluid. The SST-400 GEO steam turbine can be
deployed in geothermal power plants that operate with
superheated direct steam (dry steam) or with saturated
steam produced on pressure reduction of the thermal fluid
(flash principle). The turbine can also be deployed in the
direct or flash steam cycle of combined direct or flash
steam/binary systems (flash/binary combined cycle).The
low steam parameters and the aggressive constituents of the
thermal fluid sometimes result in extensive corrosion. As a
result, these plants require specially adapted steam turbines.
The SST-400 GEO is suitable for live steam temperatures up
to 250°C, with steam pressures up to 12 bar absolute, and
includes resource- and turbine-stage-specific high-grade
materials as well as special features for moisture removal at
every stage.