Design of the intermediate heat exchanging-depressurizing loop for low pressure operation of the SI cycle

Sulfur-Iodine (SI) has been researched for many years as a favorable candidate of thermo-chemical process for nuclear hydrogen production. However, there are obstacles to be actualized the cycle such as efficiency, material problems, economics, and etc. Reactants used in the SI cycle are extremely corrosive and harsh operating condition (e.g., over 50 bar and 700 .deg. C) accelerates the corrosion problem. Highly anticorrosive materials should be used as structural materials and those metals necessarily lead to increase of large capital costs. Ceramics such as SiC was suggested structural material, but it is not easy to obtain processability and high quality sealing at high pressure condition. The authors suggest a low pressure operation of SI cycle can reduce the corrosion problem by eliminating high pressure condition. In this case, the large pressure difference between the primary (nuclear reactor) side and the secondary (hydrogen plat) side can be a big burden to heat exchanger designers. In this article, the authors describe the effect of low pressure operation of the SI cycle and how to solve pressure difference between primary and secondary sides by adopting an intermediate heat exchanging and depressurizing loop