碘硫循环制氢被认为是最具发展前景的大规模、清洁、高效的制氢方法之一。然而碘硫循环过程复杂，单纯依靠实验的方法很难完成对该过程的总体工艺设计和流程优化，所以使用过程模拟方法对碘硫循环进行研究具有必要性。本文使用商业化工模拟软件Aspen Plus对碘硫循环过程进行模拟分析和过程优化。碘硫循环过程分为三个部分：Bunsen反应部分、硫酸分解部分和氢碘酸分解部分。本文首先研究了模拟难度较大的Bunsen反应部分和氢碘酸分解部分。在Bunsen反应部分的模拟中，由于物性体系特殊、软件数据库不够完善，商业模拟软件不能预测和计算Bunsen反应产物的分相问题。本文通过实验研究确定了Bunsen反应产物的分相条件，并开发出了由Bunsen反应产物总组成计算分相后的两相组成以及两相分别占Bunsen反应产物总量的摩尔分数的计算方法。使用VC++和Matlab将分相判断的算法和计算两相组成的算法分别编写成计算机程序并能够与Aspen Plus软件联合计算，扩展了商业模拟软件的功能，完成了对Bunsen反应部分的计算机建模。在氢碘酸分解部分的模拟中，由于HI-I2-H2O的气液平衡性质十分复杂，模拟软件中热力学数据库的不足使氢碘酸精馏的计算难以收敛。本文调用OLI数据库并使用文献发表的热力学性质数据修正模拟软件中的物性数据库，使软件能够准确地预测HI-I2-H2O的气液平衡关系并使精馏计算能够收敛。本文还在大量实验的基础上，利用excel编制了电渗析装置(EED)的模拟模型并嵌入到Aspen Plus模拟软件中，实现了对EED装置的模拟。在完成了热力学数据库的修正和EED的编程之后，建立了氢碘酸分解部分的模拟模型，并通过模型计算对氢碘酸分解部分的物料内循环路径进行了优化。以Bunsen反应部分的模型和氢碘酸分解部分的模型为基础，建立了碘硫循环全过程的模拟模型。使用本实验室已经建成的原理验证性制氢台架的运行实验数据验证了模型计算结果的可靠性。使用全过程模拟模型对碘硫循环制氢过程进行了灵敏度分析和流程优化，并依据优化的流程和参数对实验室规模的制氢台架（设计产氢量100NL/h）进行了物料衡算和能量衡算，给出了总流程图、过程单元参数、关键物流参数，并提出了进一步提升制氢效率可以采取的措施的建议，为实验室规模制氢台架的建设和运行提供了重要依据。
The iodine-sulfur thermochemical cycle process (I-S process) is considered as one of the most promising approaches for large-scale, high-efficient hydrogen production in future. It takes water as the raw material, and does not emit greenhouse gases during the production process. However, I-S process is so complex that it is quite difficult to analyze and optimize the entire flow sheet of the process. It is necessary to investigate the I-S process through chemical engineering simulation. This study conducted simulation and optimization of the I-S process using commercial process simulation software “Aspen Plus”.I-S process comprises three sections: Bunsen reaction section, H2SO4 decomposition section, and HI decomposition section. In Bunsen reaction section, the commercial simulation software cannot be used for predicting the liquid-liquid phase separation behavior of the Bunsen products due to the insufficiency of the database. The phase separation behavior and characteristics of the Bunsen reaction products at 20 and 80 ºC were investigated via experiments and the algorithm to calculate the compositions of the two liquid phases was developed. A phase separation judgement software and a two-phase composition computing software were compiled using VC++ and Matlab. The developed softwares can be used to ascertain the phase state of the Bunsen reaction products and calculate the compositions of the two liquid phases by inputting the overall composition of the Bunsen reaction products. The self-developed softwares make up the shortage of Aspen Plus and are available to simulate the Bunsen section. In the HI section, on account of the insufficiency of the commercial software database, the calculation of distillation column cannot converge. OLI database was used and the parameters of the thermodynamic models in the database was updated according to literature data. After parameter adjustment, the simulation software was capable of predicting the vapor-liquid equilibrium of HI-I2-H2O mixture accurately, and the calculation of distillation column could converge. The electro-electrodialysis cell (EED) model was built in excel software by regressing the experimental data. This model was embedded into the flow sheet in Aspen Plus, making up the shortage that Aspen Plus cannot calculate the electrochemical process. The flow sheet model of the HI section was built, and several different inner cycle circuit designs of the streams in this section were analyzed and compared.Subsequently, on basis of the simulation models of Bunsen and HI section, the whole flow sheet of the I-S process was modeled. The experimental data obtained in the previous test for the verification of I-S cycle were used to validate the simulation model.Finally, sensitivity analysis and optimization for the I-S process was carried out using the simulation model. Mass balance and heat balance calculation were implemented for the design of lab-scale hydrogen production facility (hygeogen production rate of 100 NL/h) based on the optimized flow sheet and parameters. The final flow sheet, parameters of the process units, parameters of the key streams, and methods for further improvement of the efficiency were provided.
