The Effects of Sulfide and Flow Rate on Corrosion Behavior of Duplex Steel 1.4462 in the Artificial Molasse Basin Fluid

摘要

Within the last years the use of geothermal energy as feasible energy source has risen and is going to replace fossil fuel supply more and more. Nevertheless, service conditions in geothermal facilities are due to the chemical composition of hydrothermal fluids and temperatures, in many cases, extreme in terms of corrosion. Since the construction of geothermal power plants shall be economical with maximum life service, materials selection based on preliminary material qualification is essential to guarantee a secure and reliable operation of those facilities.rnThe materials selection depends on several terms like the chemical composition of the produced aquifer fluid as well as service conditions like pressure, temperature and flow rate etc. The duplex steel, this contribution deals with, is often used as all-round solution, because of its combination of good mechanical and corrosion properties and its lower costs compared to other highly alloyed materials. In the case of the artificial geothermal fluid of Molasse Basin which is a low saline, slightly alkaline water, this contribution shall illustrate the effects of sulfides (present as (NH_4)_2S in Molasse Basin aquifer) and flowing respectively stagnating water as it can be found during maintenance or downtime of a power plant.rnThe duplex steel 1.4462 in the artificial Molasse Basin fluid shows an excellent corrosion resistance against pitting and uniform corrosion. Nevertheless, there are effects on its corrosion behavior caused by sulfide and flow rate of the fluid as shown in the figure below.