Experimental study and design of the sulfuric acid catalytic decomposer for the nuclear hydrogen production

Abstract

The Iodine-Sulfur (IS) cycle should overcome many engineering challenges to commercialize and prove its feasibilities to compete with other thermo-chemical cycles. We have to solve some critical issues such as structural material, harsh operating condition and high capital costs for its realization. In this study, the experimental studies and design of the sulfuric acid decomposition for IS cycle have been performed to develop a highly economic low pressure (HELP) IS cycle for practical applications in real process. Main research subjects are (a) design of an intermediate heat exchanging-depressurizing loop, (b) design of a catalytic SO3 decomposer using Fe2O3 catalyst, and (c) material-corrosion resistant tests for the sulfuric acid decomposer. In the first study, an intermediate heat exchanging-depressurizing loop was devised to eliminate high operating pressure in the hydrogen side as well as technical challenges due to a large pressure difference between the reactor side and the hydrogen side. Molten salts are adequate candidates as working fluids under the high-temperature condition with homogeneous phase during pressure changing process. Using molten salts, 0.38 - 0.77% of pumping work is required to change the pressure from 1bar to 7MPa when the heat consumption of the hydrogen side is 54MW from 600MWth nuclear reactor. Li2BeF2 was selected as a possible candidate based on preliminary economic and thermal hydraulic consideration In the second study, iron (III) oxide (Fe2O3) was selected for high temperature decomposition on the assumption of commercialization considering its proper kinetics, stability and price. Since the quantitative data of the selected material are rare in open sources, this study started with collecting the very basic empirical data as well as practical implications for actual design. Experimental results of stability tests with Fe2O3 powder showed that over 65% of SO3 conversion was secured during 110 hours operation. We experim...