碘硫循环制氢中HI浓缩分离工艺的研究进展

综述了碘硫循环制氢中用于HI浓缩分离的3种主要技术路线,即磷酸萃取精馏、反应精馏以及电解电渗析预浓缩-精馏的研究进展,对各路线的过程原理、操作流程、能量利用效率等方面进行了讨论,在此基础上对比了其各自的优点和不足之处,并对其应用前景进行了展望。其中,磷酸萃取精馏开发最早,相对成熟,但操作流程复杂,运行效率需进一步提升;反应精馏流程有望以高集成度取得高效率,但所需条件非常苛刻,其设备开发、工艺实验等工作亟待展开;近年来发展较快的电解电渗析预浓缩-精馏工艺由于具有操作简单,条件温和,浓缩效率高等优点而具有较好的应用前景,其进一步工艺放大、模块化以及与精馏的高效协同等都是未来研究的重点和难点。     

THERMODYNAMIC CONSIDERATIONS ON THE PURIFICATION OF H2SO4 AND HIX PHASES IN THE IODINE-SULFUR HYDROGEN PRODUCTION PROCESS

The reaction equilibrium and phase equilibrium in H₂SO₄ and HIx phases produced by the Bunsen reaction of the iodine-sulfur thermochemical hydrogen production process were examined using a chemical process simulator, ESP, with a thermodynamic database based on the mixed solvent electrolyte model. At temperatures lower than ca. 110°C, the reaction of HI and H₂SO₄ produced elemental sulfur in both phases. At higher temperatures, the reverse Bunsen reaction occurred, and SO₂ was produced in the H₂SO₄ phase. In the HIx phase, conversely, SO₂ formation predominated in a narrow temperature range and H₂S was produced with the increase in temperature. The presence of N₂ gas lowered the temperature of the predominant reaction change. A feed of O₂ for purification was proposed to suppress the consumption of objective components in the H₂SO₄ phase purification, and an O₂ feed to the HIx phase for the suppression of H₂S and S impurities was proposed by the simulation.     

Modeling and validation of the iodine‐sulfur hydrogen production process

The iodine‐sulfur thermochemical water‐splitting cycle (I‐S process) is one of the highly efficient, CO₂‐free, massive hydrogen production methods. We simulated the I‐S process through commercial software programs Aspen Plus and OLI database with the aid of self‐developed models to analyze the overall running status of the process and to decrease the investment and time consumption of experiments. A two‐phase separator model operating at 353 K and an electro‐electrodialysis (EED) cell model working at 338 K were built on the basis of experimental data. The entire flow sheet of the I‐S process was modeled based on the two self‐developed models. The simulation models were validated through the experimental results obtained from the closed cycle I‐S facility (IS‐10) in our laboratory. By employing the simulation program, sensitivity analyses of the important parameters in the process were carried out, including the ratio of the distillate to the feed rate of the H₂SO₄ distillation column, reflux ratio of the H₂SO₄ column, H₂SO₄ conversion ratio, HI molality in the EED cathode outlet stream, and HI mole fraction in the liquid and vapor distillates of the HI distillation column. The key parameters significantly affecting the input duty were determined; that is, the ratio of the distillate to the feed rate of the H₂SO₄ distillation column and the HI molality in the EED cathode outlet stream. The optimal values of the analyzed parameters were also discussed. The simulation program we developed is a useful tool that can evaluate and optimize the I‐S process. © 2013 American Institute of Chemical Engineers AIChE J 60: 546–558, 2014     

甲醇双效精馏过程参数优化及有效能分析

利用流程模拟软件Pro Ⅱ对甲醇双效精馏过程进行了参数优化,结果表明,适合的操作压力为800kPa,加压塔塔底与塔顶质量流量适合比为1.66.在优化参数的基础上对过程进行了模拟,并对传统两塔流程及双效梢馏流程进行了热力学分析,结果表明,双效精馏过程热力学效率为15.95%,与传统两塔流程相比,效率提高了7.72%.     

乙酸-水-乙酸正丁酯三相体系的热力学分析与共沸精馏过程模拟

乙酸-水-乙酸正丁酯体系的分离是汽-液-液三相共沸精馏过程,相分裂的判断和精馏塔算法的改进是进行该精馏过程模拟的两个主要问题.本文根据现有的基础数据给出了该体系的逸度和活度因子计算模型,然后讨论了Gibbs自由能的变化规律和热力学稳定性条件,给出了该体系相分裂判据,并得到了完整的相分裂区;最后,根据多相精馏的特点对现有的精馏塔算法进行了改进,对该三元非均相共沸精馏过程进行了数值模拟,所得沿塔温度和各组分浓度分布曲线与工业实测数据吻合.     

Logic hybrid simulation-optimization algorithm for distillation design

In this paper, we propose a novel algorithm for the rigorous design of distillation columns that integrates a process simulator in a generalized disjunctive programming formulation. The optimal distillation column, or column sequence, is obtained by selecting, for each column section, among a set of column sections with different number of theoretical trays. The selection of thermodynamic models, properties estimation, etc. is all in the simulation environment. All the numerical issues related to the convergence of distillation columns (or column sections) are also maintained in the simulation environment. The model is formulated as a Generalized Disjunctive Programming (GDP) problem and solved using the logic based outer approximation algorithm without MINLP reformulation. Some examples involving from a single column to thermally coupled sequence or extractive distillation shows the performance of the new algorithm.     

费托反应水中有机物初步分离的模拟研究

本文提出了费托反应水中有机物初步分离流程,利用Aspen Plus过程模拟软件中的RadFrac精馏模块,采用NRTL热力学模型,对该流程作了模拟。对精馏塔的基本参数如理论板数、回流比、进料板位置等进行了模拟优化。同时将试验与模拟结果进行了对比,二者基本吻合。     

ON THE EXERGY ANALYSIS OF BINARY DISTILLATION COLUMNS WITH HEAT INTEGRATION

The exergy analysis is done for the conventional distillation, the VR (Vapor Recompression) distillation, and the SRV (Secondary Reflux and Vaporization) distillation with the aid of computer simulation. It is shown that the careful use of thermodynamic diagrams helps us for the exergy analysis.     

Effect of thermodynamic parameters on prediction of phase behavior and process design of extractive distillation

Extractive distillation was investigated for separation of the minimum azeotrope of n-propanol/water,via the Aspen Plus simulation platform.Experimental data of n-propanol/water,which could pass the thermodynamic consistency test,were regressed to get suitable binary interaction parameters (BIPs) by the UNIQUAC thermodynamic model.The azeotrope system was heterogeneous in the simulation with built-in BIPs,which was contrary to the experimental data.The study focused on the effect of thermodynamic parameters on the prediction of phase behavior,and process design of extractive distillation.N-methyl-2-pyrrolidone (NMP) and ethylene glycol were used as solvents to implement the separation.Processes with built-in and regressed BIPs were explored,based on the minimum total annual cost (TAC).There were significant differences in the phase behavior simulation using different thermodynamic parameters,which showed the importance of BIPs in the design and optimization of extractive distillation.     

Optimal Design and Optimal Operation of Separate Heat Pump Distillation

For a distillation system, in which relative volatility is large in low composition range and small in high composition range, using separate heat pump distillation (SHPD) can markedly save energy. In this paper, vapour flow rate to compressor is proposed as a parameter for system optimization, from the viewpoint of system energy balance. This parameter can be used for both optimal design and optimal operation of SHPD. Mathematical models for optimal design and optimal operation are formulated to minimize total annual cost and annual operating cost respectively. Optimal design of SHPD is performed and evaluated through process simulation, for a typical case study for the distillation of ethanol‐water system. The results show that SHPD has notable energy saving and economic benefit when compared with conventional distillation. Optimal operation of SHPD is also evaluated for changes in feed composition which is an operating variable.     

Overall efficiency evaluation of commercial distillation columns with valve and dualflow trays

The main objective of this work is to establish appropriated ways for estimating the overall efficiencies of industrial distillation columns with valve trays with downcomer and dualflow trays. The knowledge of efficiencies has fundamental importance in the design and performance evaluation of distillation columns. Searching in the literature, a tree of alternatives was identified to compose the tray efficiency model, depending on the mass transfer models, the liquid distribution and vapor flow models on the tray, the liquid entrainment model, the multicomponent mixture equilibrium model, the physical properties models, the height of froth on the tray model and the efficiency definition. In this work, different methods to predict the overall efficiency of distillation columns with valve and dualflow trays were composed and compared with data from three commercial distillation columns under different operating conditions. The models were inserted in the Aspen Plus 12.1 simulator, in Fortran language, together with tray geometrical data, fluid properties and operating data of the distillation columns. For each column, the best thermodynamic package was chosen by checking the temperature profile and overhead and bottom compositions obtained via simulation against the corresponding actual data of industrial columns. A modification in the fraction of holes evaluation that is jetting parameter of the Garcia's hydraulic model of dispersion above the tray was proposed. This modification produced better results than the original model to predict the fraction of holes that are jetting and in the efficiency of dualflow trays and similar results to Garcia model in the efficiency evaluation of valve trays. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

SENSITIVITY AND UNCERTAINTY OF PROCESS DESIGNS TO THERMODYNAMIC MODEL PARAMETERS: A MONTE CARLO APPROACH

Process simultalion relies heavily on the calculation of physical properties through thermodynamic models. The parameters in these models are subject to uncertainties that may, at first, appear to be small. However, the designs developed through use of these models can be significantly sensitive to these parameter uncertainties. Previous studies have considered special cases of design error or have involved simple sensitivity analyses close to the optimum design case. In the present work, we use Monte Carlo simulation with Latin Hypercube Sampling to quantify the probability of design errors. An example of binary distillation with phase-equilibrium calculations from a cubic equation of state is used to illustrate the technique.     

Advances on modeling and simulation of alcoholic distillation. Part 2: Process simulation

Several studies developed by the authors on the application of process simulators to the distillation processes of alcoholic mixtures are analyzed and discussed in this second part of the series on advances on modeling and simulation of alcoholic distillation. Three study cases are presented and discussed to show the usefulness of simulation packages, and in particular of ChemCAD: (i) production of whisky in a sequence of double batch distillation; (ii) production of brandy in a single continuous column; and (iii) production of neutral spirits in a sequence of multiple columns (concentrator, light component separator, and rectification column). In all cases the selection of the thermodynamic models considered previous studies as discussed in Part 1 of the series in which the NRTL model was recommended for phase equilibrium modeling. Applications of two industrial and pilot plant cases are presented, so the validity of the simulations and the appropriateness of the thermodynamic and process simulation studies presented in this series of papers. The main conclusion of the study is that simulators can play an important role in understanding alcoholic distillation processes, in optimizing resources and in making distillation of wine and musts a more efficient process.     

2-乙基丙烯醛精馏分离过程模拟与实验研究

基于Aspen Plus软件,利用软件的物性估算功能及UNIFAC-HOC热力学模块,完成了数据库中缺少组分2-乙基丙烯醛物性估算,获得了模拟所需基础数据,通过对软件的相平衡曲线、残余曲线的分析,设计了分离体系的4塔分离流程,采用简捷模拟、严格模拟和灵敏度分析模块完成精馏塔的设计和操作参数的优化,从而获得了纯度达到99%的2-乙基丙烯醛精馏分离流程和操作条件。间歇精馏实验表明:模拟共沸物组成符合实际过程,模拟结果可以指导实际过程的分析和设计。     

双效精馏节能技术研究进展

精馏是化工生产中的重要操作单元,由于其能耗大,节能潜力高而备受关注。双效精馏是利用2个精馏塔的操作压力不同而设计的,通过重复利用给定数量的能量来提高精馏设备的热力效率。主要介绍了双效精馏的3种典型的工艺流程：顺流双效精馏、平流双效精馏、逆流双效精馏,并从能源利用方面分析它们的特点和适用条件。综述了近年的双效精馏的模拟优化成果以及其节能现状与发展趋势。     

Simulation of 1,3-butadiene extractive distillation process using N-methyl-2-pyrrolidone solvent

A computer simulation was performed using a commercial process simulator, Aspen Plus, for NMP (Nmethyl-2-pyrrolidone) extractive distillation process to separate 1,3-butadiene from the C₄ hydrocarbon mixtures. The Redlich-Kwong equation of state and NRTL activity coefficient model were used to calculate thermodynamic properties in the simulation of the extractive distillation process. Binary parameters of the NRTL model not provided in the simulator were estimated using the UNIFAC method. The simulation results of the 1,3-butadiene recovery from the C₄ mixtures were in good agreement with the plant operation data. The process simulation showed that the material balances in the extractive distillation were successfully predicted for various NMP solvent flow rates. The results obtained in this work provided the optimum solvent rate and the reflux ratio for the NMP extractive distillation process to separate 1,3-butadiene from the C₄ mixtures.     

ON THE DYNAMIC PROPERTIES OF THE EXTENSIVE VARIABLE CONTROL STRUCTURES

The purpose of this paper is to investigate the dynamic properties of controller structures synthesized using extensive thermodynamic variables of a process. Several state-space and frequency domain multivariable techniques, including INA, and Modal Interaction Analysis, are used in order to evaluate the dynamic properties of these control structures. These structures show zero steady state interaction and minimal dynamic interaction for all processes examined. Dynamic simulation of several application examples, including distillation columns and a network of two stirred tank heaters in series, shows that the loops in these structures can also be tuned with minimum effort. Comparison of the proposed structures, with the conventional parallel single-input single-output control structures, shows the advantages of the proposed method.     

苯乙烯装置流程模拟

利用PROCESS过程模拟软件对苯乙烯装置进行模拟计算。采用NRTL,SRK,BK10等热力学方法,选择合适的模型参数。计算结果与国外设计吻合,可应用于国产化设计。