황-요오드(Sulfur-Iodine, SI) 공정은 물을 분해시켜 수소를 생산하는 열화학 공정으로 공정에 사용되는 황과 요오드는 재순환된다. SI 공정 중 요오드가 분리 순환되는 Section III에서는 공정 효율 개선을 위해 다양한 방법이 개발되고 있다. EED(electro-electrodialysis)를 이용한 방법은 추가적인 화합물이 필요하지 않는 공정으로 Section III의 효율을 높일 수 있으나 공정 흐름에 포함된 요오드에 의해 상당한 부하가 걸리게 된다. 이를 해결하기 위해 EED 앞에 요오드제거 공정으로 결정화 방법이 고려되고 있다. 본 연구에서는 요오드 결정화 반응기 설계를 위한 기초 자료 확보를 위해 I2 포화 HIx 용액에서 요오드 결정의 침강 속도를 모델링 하였다. HIx 용액 조성은 열역학 모델인 UVa를 이용하여 결정하였으며 용액 물성은 순수한 물성들과 상관관계식을 활용하여 추산하였다. Multiphysics 전산툴을 이용하여 침강에_x000D_ 따른 속도 변화를 계산하였으며 요오드 직경과 온도에 따른 변화를 추산하였다. 직경(1.0~2.5 mm)과 온도(10~50 ℃) 범위에서 요오드는 0.5 m/s 내외의 종말 속도를 보이며 이 속도는 용액의 점도 보다 밀도에 더 크게 영향을 받는 것으로 나타났다.

SI process is a thermochemical process producing hydrogen by decomposing water while recycling sulfur and iodine. Various technologies have been developed to improve the efficiency on Section III of SI process, where iodine is separated and recycled. EED(electro-electrodialysis) could increase the efficiency of Section III without additional chemical compounds but a substantial amount of I2 from a process stream is loaded on EED. In order to reduce the load, a crystallization technology prior to EED is considered as an I2 removal process. In this work, I2 particle sinking behavior was modeled to secure basic data for designing an I2 crystallizer applied to I2-saturated HIx solutions. The composition of HIx solution was determined by thermodynamic UVa model and correlation equations and pure properties were used to evaluate the solution properties. A multiphysics computational tool was utilized to calculate particle sinking velocity changes with respect to I2 particle radius and temperature. The terminal velocity of an I2 particle was estimated around 0.5 m/s under considered radius (1.0 to 2.5 mm) and temperature (10 to 50 ℃) ranges and it was analyzed that the velocity is more dependent on the solution density than the solution viscosity.

Hydrogen Production SI Process Crystallizer Iodine Terminal Velocity

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