Abstract
A new thermochemical hybrid hydrogen production process (HHLT: thermochemical and tlectrolytic Hybrid Hydrogen production process in Lower Temperature range) for sodium cooled FBR is proposed. HHLT is based on sulfuric acid (H2SO4) synthesis and the decomposition processes (named "Westinghouse process") developed earlier, and SO3 decomposition process is facilitated by electrolysis with ionic oxygen conductive solid electrolyte which is extensively utilized for high-temperature electrolysis of water.
In the present study, theoretical total voltage required for electrolysis and thermal efficiency of HHLT considering chemical reactions were evaluated. Furthermore, advantages and technical problems of HHLT were considered.
Evaluated theoretical total voltage was expected to be lower than about 0.5V. Theoretical thermal efficiency was changed under the influence of H2SO4 concentration and heat recovery, and maximum efficiency obtained in this evaluation was about 55%.
HHLT has many advantages such as, simple process flow, low corrosion of structural materials and low risk for hydrogen explosion. Important problems to be solved consist of feasibility of electrolysis of SO3 using solid electrolyte, development of high performance oxygen conductive solid electrolyte under SO3 atmosphere, process structural materials and sulfuric acid synthesizer with high electrolyzing efficiency.
