sCO2flex partners at the REZ Research Center presented their paper on “Microstructural Evaluation of HR6W and T92 after Supercritical CO2 Exposure” at the 29th international conference nuclear energy for new Europe.
The supercritical carbon dioxide Brayton cycle is being considered as an innovative
technology with potential for replacement of conventional steam cycles. Increased efficiency
and operational flexibility at specific operational parameters are expected that can be beneficial
for various power sources including nuclear, fossil or renewable. The optimization of the
design of supercritical CO2 (sCO2) Brayton cycle and of its main components is essential to
achieve requested parameters of the thermal cycle. The optimization requires not only the cycle
layout and the components design studies but also selection of the materials. The materials
research is critical in the field of the sCO2 technology development due to the fact that the main
benefits of the sCO2 cycles are gained at extreme operational conditions such as temperatures
above 550°C and pressures up to 25 MPa.
This work addresses the testing of the resistance HR6W and T92 materials before and
after exposure. The corrosion behaviour of the materials selected for the high temperature
components in the sCO2 environment was investigated. The corrosion behaviour was evaluated
by observation of the surface and cross-section of the samples after exposure in sCO2 by
microscopy methods – SEM and LOM. The results summarise the experimental campaign
characterized by 1000 hours of exposure of the selected steels in the sCO2 at 550°C and
25 MPa. The materials compatibility testing was conducted for materials that were identified
as potential candidates for high temperature components of the sCO2 cycles such as boiler, heat
exchangers or pipes. Testing was completed for samples in the unstressed conditions. The
samples exposed to sCO2 showed the oxidation of the surface, the extent of which varied
considerably between the materials tested. Examination of cross sections of the samples showed
perceptible differences of the formation of oxide layers on the surface caused by the sCO2
exposure.
Read Paper HERE
Check out NENE 2020 Conference proceedings HERE