Structural Design and Numerical Investigation of the Sulfuric Acid Decomposer in the Thermochemical Iodine-Sulfur Cycle for Hydrogen Production
The decomposition of sulfuric acid is a key step influencing the hydrogen production efficiency of the thermochemical iodine-sulfur cycle.This article designed a pilot-scale bayonet sulfuric acid decomposer that met a hydrogen yield of 1 m3/h via numerical simulation.Firstly,the reaction kinetic parameters of the Fe2O3 catalyst were experimentally determined,with the pre-exponential factor and activation energy being 1.439×107 s-1 and 125.63 kJ/mol,respectively.Then,a comparative simulation was conducted on the decomposers of three structural forms.The results showed that the"half-area"inner tube had a stronger heat transfer effect than the"half-diameter"inner tube in the decomposer,reducing the length of the preheating section by 43.27%and decreasing the catalyst usage by 23%to achieve the same decomposition rate.The third structure further optimized the heat transfer effect of the preheating section by filling SiC balls into the preheating section based on the"half-area"form,reducing the length of the preheating section by 70.51%.The increase in pressure drop and energy consumption caused by the SiC balls were marginal.Furthermore,the third structure had optimal cost-effective performance when the preheating and catalytic section lengths were respectively 870 mm and 333 mm,while the SO3 decomposition rate reached 73.73%,corresponding to a theoretical H2 yield of 1.228 8 m3/h.When the heating temperature of the decomposer's outer wall decreased to 860 ℃,the SO3 decomposition rate dropped to 60%,exactly corresponding to a H2 yield of 1 m3/h.This study provides a reference for the design of a pilot-scale sulfuric acid decomposer.
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