Upgrading and Life Cycle Extensions of Geothermal Energetic Pumps and Turbines by Thermal Spray Process and Multi Composite Technology

The European Council in 2007 adopted ambitious energy and climate change objectives for 2020 – to reduce greenhouse gas emissions by 20%, rising to 30% if the conditions are right, to increase the share of renewable energy to 20%, and to make a 20% improvement in energy efficiency. Achieving energy- efficient Europe is the first out of the five priorities of the new energy strategy. Therefore in the market need, the steam high temperature turbine engine remains the prim over of power generation. Thus any significant technological improvement towards better performance and energy efficiency in this field of turbines will have a direct positive impact in the short term on energy strategy in Romania and Iceland.

It has been estimated that the turbine corrosion problems has a cost of two billion Euros per year to the EU utility industry. Today, the lifetime of materials used in steam turbines need to be increased by augmenting their resistance to corrosion at high temperature and simultaneously decrease the turbine cost.

The “hot parts” of co-generative systems are subjected to a series of tribological stresses due to erosion at speeds of over Mach 1, abrasive wear, thermal shock, etc. The critical wear factors that work on the turbines “hot parts” at temperatures above 400-4500C, are quick thermal shock, particle speed erosion, corrosion, adhesion, thermal factors a.s.o.

The corrosion process in a steam turbine depends on temperature, pressure, chemistry, mechanical and vapour carryover of impurities and also on water treatment (distribution between the vapours, the surface film and material of the rotor blades, heat transfer properties etc).

This process can be tackled using new materials, with good control of geothermal steam chemistry and new blades surfaces. These surfaces can be realized using ceramic or metallo-ceramic materials as coating layers of the blades, thus preventing corrosion and offering good turbine reliability.

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