• 한국수소및신에너지학회논문집
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• 제21권3호
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• pp.158-166
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• 2010

The purification of two liquid phases ($H_2SO_4$ phase and HIx phase) formed from a Bunsen reaction in Sulfur-Iodine (SI) hydrogen production process was investigated in order to operate SI process efficiently. The each synthetic solution for two liquid phases contained impurities was prepared on the basis of a proper composition obtained from Bunsen reaction. The purification of each solution was performed by counter-current flow using a packed column at different temperatures and $N_2$ flow rates. As the results of purification, impurities existed in each phase were decreased with increasing the temperature and the $N_2$ flow rate. In particular, the increase of the $N_2$ flow rate at the lower temperatures was effective to remove impurities by a reverse Bunsen reaction without side reactions. On the whole, it may be concluded that the purification of each phase is accomplished by mixing effects of the stripping, the evaporation, and the reverse Bunsen reaction.

• 한국수소및신에너지학회논문집
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• 제21권6호
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• pp.479-486
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• 2010

In order to confirm the effect of $HI_x$ solution on Bunsen reaction in Sulfur-Iodine thermochemical hydrogen production process, the reaction was investigated using $HI_x$ solution as a reactant. The phase separation characteristics of reaction with $HI_x$ solution were compared with the reaction using $I_2$ and $H_2O$ as reactants. Firstly, saturation points of $I_2$ in $HI_x$ solution at various temperatures were investigated to determine reaction conditions. With increasing temperature, the amounts of unreacted $I_2$ and $H_2O$ in $HI_x$ solution were increased, while impurities (HI in $H_2SO_4$ phase and $H_2SO_4$ in $HI_x$ phase) in each phase were decreased. The volumes of $H_2SO_4$ phase obtained from Bunsen reaction with $HI_x$ solution was relatively less than those obtained from the reaction with $I_2$ and $H_2O$. The difficulty of phase separation in Bunsen reaction using $HI_x$ solution may be due to the insufficient amount of $H_2O$ existed in $HI_x$ phase after reaction. Therefore, we concluded that the supplement amount of $H_2O$ should be calculated on the basis of the moles of HI and $H_2SO_4$ and added to the reaction system for good phase separation.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.279-286
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• 2020

In this article, we develop a reactive distillation (RD) column configuration for the production of hydrogen. This RD column is in the HI decomposition section of the sulphur - iodine (SI) thermochemical cycle, in which HI decomposition and H₂ separation take place simultaneously. The section plays a major role in high hydrogen production efficiency (that depends on reaction conversion and separation efficiency) of the SI cycle. In the column simulation, the rigorous thermodynamic phase equilibrium and reaction kinetic model are used. The tuning parameters involved in phase equilibrium model are dependent on interactive components and system temperature. For kinetic model, parameter values are adopted from the Aspen flowsheet simulator. Interestingly, there is no side reaction (e.g., solvation reaction, electrolyte decomposition and polyiodide formation) considered aiming to make the proposed model simple that leads to a challenging prediction. The process parameters are determined on the basis of optimal hydrogen production as reflux ratio = 0.87, total number of stages = 19 and feeding point at 8th stage. With this, the column operates at a reasonably low pressure (i.e., 8 bar) and produces hydrogen in the distillate with a desired composition (H₂ = 9.18 mol%, H₂O = 88.27 mol% and HI = 2.54 mol%). Finally, the results are compared with other model simulations. It is observed that the proposed scheme leads to consume a reasonably low energy requirement of 327 MJ/kmol of H₂.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.13-21
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• 2016

The Sulfur-Iodine thermochemical hydrogen production process (SI process) consists of the Bunsen reaction section, the $H_2SO_4$ decomposition section, and the HI decomposition section. The $HI_x$ solution ($I_2-HI-H_2O$) could be recycled to Bunsen reaction section from the HI decomposition section in the operation of the integrated SI process. The phase separation characteristic of the Bunsen reaction using the $HI_x$ solution was similar to that of $I_2-H_2O-SO_2$ system. On the other hands, the amount of produced $H_2SO_4$ phase was small. To investigate the effects of $SO_2$ solubility on Bunsen reaction, the continuous Bunsen reaction was performed at variation of the amounts of $SO_2$ gas. Also, it was carried out to make sure of the effects of partial pressure of $SO_2$ in the condition of 3bar of $SO_2-O_2$ atmosphere. As the results, the characteristic of Bunsen reaction was improved with increasing the amounts and solubility of $SO_2$ gas. The concentration of Bunsen products was changed by reverse Bunsen reaction and evaporation of HI after 12 h.

• 공업화학
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• 제29권1호
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• pp.56-61
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• 2018

황-요오드(SI) 공정의 통합 운전을 위한 분젠 반응 단계에서, $I_2$ 및 $H_2O$ 반응물들은 $HI_x$ 용액 내 용해된 성분들로써 공급된다. $HI_x$ 용액과 $SO_2$ 공급을 이용하여 분젠 반응이 수행될 때 $HI_x$ 상 내 대부분의 $H_2SO_4$ 생성물이 존재하며, 이에 따라 $HI_x$ 상에 대한 $H_2SO_4$ 상의 부피 비가 매우 낮다. 본 연구에서 우리는 상 분리 성능을 향상시키기 위해 $HI_x$ 용액을 이용한 분젠 반응에 대한 초음파 조사의 효과들을 연구하였다. 분젠 반응과 함께 초음파가 조사될 때 $HI_x$ 상으로부터 $H_2SO_4$ 상으로 이동된 $H_2SO_4$의 양은 최대 58.0 mol%까지 증가하였으며, $H_2SO_4$ 상의 부피 또한 최대 13.1 vol%까지 증가하였다. 특히, 상 분리에 대한 초음파 조사의 효과는 온도, $I_2$ 및 $H_2O$ 공급 농도가 감소함에 따라 향상되었다. 초음파 조사는 $HI_x$ 상 내 반응 평형을 미시적으로 이동시킴으로써 추가적인 $H_2O$ 분자들의 형성을 유도하였다. 이로부터 추가적으로 생성된 $H_2O$ 및 분리된 $H_2SO_4$ 분자들이 $H_2SO_4$ 상으로 이동할 수 있는 더 많은 $H_2SO_4{\cdot}xH_2O$ (x = 5-6) 착물들을 형성하였다.