UREX+ 304L stainless steel centrifugal contactor corrosion due to hydrodynamic effects
Conference Paper
Overview
Overview
abstract
UREX+ is a solvent extraction process for partitioning spent fuel constituents to lead to safer and cheaper disposal of high-level waste. The procedure is based on an annular centrifugal stainless steel contactor developed for solvent extraction. During the centrifugal contactor operation there are two immiscible fluid phases, aqueous and organic, that move in opposite directions as they flow from stage to stage. These phases, which are mixed to accomplish separation and later separated, flow through two different centrifugal contactor regions called "mixing" and " separation" zones. It has been reported the appearance of different hydrodynamic conditions in each region as the rotor of the contactor spins at 2000 rpm. In addition, the geometry of a centrifugal contactor is quite complex composed of sharp section changes in relative short distances. Therefore, it could be expected that flow enhanced corrosion (erosion-corrosion) might occur in UREX+ centrifugal contactors which may be specific to their complicated geometry and turbulences created by the spinning rotor. The rotating cage (RC) technique was selected to carry out corrosion tests in simulated turbulent pattern and multi-phase conditions present in the two different zones of the centrifugal contactor. After the determination of the optimum solution volume, 304L stainless steel coupons were attached in the rotated cage and subjected to corrosion under the effect of different wall shear stresses and turbulences at the rotational speeds of 500, and 1,000 rpm and temperature of 25C. All samples were weighed and characterized before and after testing. It was determined that high rotation speeds enhanced corrosion. Also the type of test solution and increased temperature impacted the corrosion resistance of 304L stainless steel. Corrosion tests results are presented based on mass loss and surface appearance which includes microstructural and surface analysis. 2010 by NACE International.
