内部能量集成的精馏塔研究进展

在阐述内部能量集成的精馏塔(HIDi C)的基础上,综述了该技术在国内外研究的最新进展,涵盖了工作原理、节能效果以及不同类型HIDi C的结构和配置,在此基础上提出了一种新型Ideal-Super-HIDi C耦合结构。最后评估了不同形式精馏系统的成本和节能效果,介绍了HIDi C的工业应用案例。     

内部热集成精馏塔的模拟及其节能特性研究

首先利用Aspen plus模拟软件,分析了压缩比和进料热状态对内部热集成精馏塔的操作特性、节能效果的影响。结果显示,与传统精馏塔相比,内部热集成精馏塔节能百分率可达30%~60%。最后,从斜率和灵敏度分析的角度优化内部热集成精馏塔的温度和压力控制点,为内部热集成精馏塔设计和工业操作提供参考依据。     

内部能量集成精馏塔的模拟研究及其节能特性分析

针对苯-甲苯和丙烯-丙烷物系,模拟分析了压缩比、进料状态及换热量分布方式对理想内部能量集成精馏塔的操作特性、所需塔内换热面积及节能效果的影响。将模拟结果与传统精馏塔及热泵精馏塔进行比较,结果显示内部能量集成精馏塔的节能效果对于不同物系有较大差别。对苯-甲苯物系,热泵精馏塔的节能效果最好,节能百分率为40％。对丙烯-丙烷物系,理想内部能量集成精馏塔的节能优势明显,节能百分率在60％～80％。本文提出了内部能量集成精馏塔热温匹配的换热量分布方式。模拟结果表明,达到同样节能效果,采用热温匹配的换热量分布方式可以在压缩比较小时大幅度减小传热面积。采用热温匹配的换热量分布方式可以在压缩比较小时大幅度减小传热面积。     

考虑反应热的乙氧基化反应精馏塔能量内部集成与优化

以正丁醇和环氧乙烷为原料合成乙二醇正丁醚(EGMBE)为例,利用数学模型和模拟分析方法,研究了包含大量反应热效应的乙氧基化反应精馏(ERD)塔中反应热的利用及系统能量优化问题。研究表明,当采用常规的、将反应段直接叠加于提馏段之上的塔设计时,反应热并没有贡献于分离操作或减小再沸器的热负荷,而只是被冷凝器中的冷却介质移走。分析了反应热的可利用途径,提出一种将反应段和提馏段分割、从反应段移出反应热供提馏段加热的内部热集成乙氧基化反应精馏结构--IHIERD。模拟结果表明,IHIERD 将使再沸器的温度从462.5 K降低到420.0 K,冷凝器负荷降低11%,外部能量输入降低14%,节能效果显著。     

内部热耦合精馏塔的操作性能与模拟

对同轴式内部热耦合精馏塔的操作性能和节能效果进行了研究,考察了全回流操作条件下,压缩比对回流量、冷凝器负荷和再沸器负荷的影响。结果表明,随着压缩比的增大,回流量、冷凝器负荷和再沸器负荷均降低。通过实验数据计算得到了该塔的理论板数和两塔间的传热量,精馏段为9块理论板,提馏段为4块理论板,当压缩比为2.2:1时,两塔间传热量为9.98kW。连续操作条件下,对内部热耦合精馏塔的节能效果进行了分析,通过与常规精馏塔的比较,内部热耦合精馏塔可节约52.3%的冷量,输入的再沸器和压缩机总负荷可节约20.34%。另外,基于实验数据,对该内部热耦合精馏塔进行了动态模拟,经连续操作下的实验验证,该内部热耦合精馏塔可在2h后达到稳定操作。     

300kt/a甲醇装置加压精馏塔操作工况的模拟分析

应用Chemsep模拟软件对甲醇精馏装置的加压塔进行模拟计算,分析了加压塔塔顶压力对加压塔的产品质量、汽液平衡、温度及回流比的影响,对加压塔操作压力进行了模拟优化。     

基于模拟分析技术和随机搜索算法的化工过程能量集成方法研究

夹点和模拟分析技术已在化工能量集成中广泛应用.今以夹点技术为基础,对化工过程系统用能进行诊断,根据"过程用能一致性"原则提出能量集成改造方案,通过改变塔压实现塔顶冷凝器与塔底再沸器的热集成多效蒸馏.夹点技术实现的优化目标仅是热回收最大或公用工程能耗最小,不能实现包括设备整体费用最小的过程全局最优化.研究基于模拟技术,通过灵敏度分析,得到精馏塔各操作参数的样本映射数据,通过多项式拟合得到参数关联方程,并在遗传算法及模式搜索中设计过程费用函数,提出了将模拟分析技术与随机搜索算法相结合的,以过程费用函数最小化为优化目标的能量集成方法.工业实例的成功设计应用证明了其有效性和可行性.     

完全能量耦合精馏塔的设计、模拟与优化

在很多的工业生产中,都需要进行精馏工作,尤其是化学工业,精馏过程的效率与化学工业的发展有着密不可分的联系。精馏过程是一个对能量消耗非常大的过程,一直以来,怎样使精馏过程更加简单、高效,怎样使精馏过程中能量利用效率更高,是相关企业和部门密切关注的问题。因此对完全能量耦合精馏塔的设计、模拟与优化的相关内容做了研究。     

完全能量耦合精馏塔的设计、模拟与优化

本文针对完全能量耦合精馏塔,基于Fenske-Underwood-Gilliland方程建立了完整的简捷设计方法,得到了各塔的实际理论板数、适宜的进料和侧线液相采出位置以及各塔回流比等参数。并在此基础上通过严格模拟,对完全热耦合精馏塔的中间组分分配比β、气相分割比R_v和液相分割比R_l等参数进行了优化,得出了它们对再沸器热负荷的影响规律。     

多效反应精馏过程生产氯化苄的能量集成

以甲苯氯化生产氯化苄为研究对象,对带侧反应器的反应精馏与精制塔串联工艺(CSRRT)进行研究及能量分析,建立了分段反应精馏与精制塔串联生产氯化苄的新工艺。利用精制塔塔顶蒸汽潜热加热第一段反应精馏塔的塔釜,建立了多效反应精馏(MERD);进一步利用侧反应器的甲苯氯化反应热加热第一段反应精馏塔的塔板物料,建立了多效透热反应精馏(MEDRD)。在相同生产要求下,对3种工艺的能耗进行比较。结果表明,MERD和MEDRD过程实现了能量的优化利用,与CSRRT过程相比,塔釜总再沸器热负荷分别降低16.8%和33.7%。     

一个用于精馏塔模拟的新模型

A new computational mass transfer model is proposed for simulating the distillation process by solving the fluctuating mass flux for the closure of turbulent mass transfer equation in order to obtain the concentration profile and the separation efficiency of distillation column. The feather of the proposed model is to abandon the conventional way of introducing the turbulent mass transfer diffusivity (dispersion coefficient) to the turbulent mass transfer equation. To verify the validity of the proposed model, a commercial scale packed column and a sieve tray column were simulated and compared with published experimental data. The simulated results were satisfactorily confirmed in both concentration distribution and separation efficiency.     

Towards further internal heat integration in design of reactive distillation columns—Part III: Application to a MTBE reactive distillation column

According to the principle introduced in the first two papers of this series, seeking further internal heat integration between reaction operation and separation operation during the synthesis, design, and operation of a reactive distillation column synthesizing methyl tertiary butyl ether (MTBE) from methanol and isobutylene is investigated. Although the MTBE reactive distillation column is characterized by complicated thermodynamic properties and multiple steady states, a substantial reduction of energy requirement and capital investment can still be achieved with the consideration of further internal heat integration between the reaction operation and the separation operation in the two existing steady states. Dynamics and operation of the resultant process designs are then examined in terms of static and dynamic analysis and sharp improvement in process dynamics and controllability is clearly identified through intensive comparison against the simple process design without the consideration of further internal heat integration between the reaction operation and the separation operation involved. It is demonstrated that the more synergistic relationship evolved during the reinforcement of internal heat integration should account for the dramatic improvement in process dynamics and controllability.     

Towards further internal heat integration in design of reactive distillation columns—Part IV: Application to a high-purity ethylene glycol reactive distillation column

In the first three papers of this series, it has been shown that strengthening internal heat integration within a reactive distillation column involving reactions with high thermal effect is really effective for the reduction of utility consumption and capital investment besides the improvement in process dynamics and operation. One important issue that remains unstudied so far is the influences of reaction selectivity upon the reinforcement of internal heat integration, since the reaction operation is often accompanied by side-reactions and the maintenance of a high selectivity is extremely necessary in process synthesis and design. A reactive distillation column synthesizing high-purity ethylene glycol through the hydration of ethylene oxide is chosen and studied in this work. Because of the unfavorable physicochemical properties of the reacting mixture separated (e.g., the fairly large volatility between the reactants and the existence of a consecutive side-reaction), the process represents a challenging problem for the reinforcement of internal heat integration. Intensive comparison is conducted between the process designs with and without the consideration of further internal heat integration between the reaction operation and the separation operation involved, and it has been found that seeking further internal heat integration still leads to a substantial reduction of energy requirement, in addition to a further abatement in capital investment. Moreover, a favorable effect is again observed upon the process dynamics and operability. These striking outcomes manifest evidently that seeking further internal heat integration should be considered in process synthesis and design irrespective of what a reaction selectivity has been assigned.     

Higher energy saving with new heat integration arrangement in heat‐integrated distillation column

In conventional heat‐integrated distillation columns (HIDiCs), the internal heat exchange is executed between the pressurized rectifying section and the stripping section, which are located at the same elevation. In such a structure, the amount of heat exchanged between two sections depends on the temperature profile of both sections. The resulting enthalpy profile inside the column departs from that in reversible distillation, which is the ideal distillation operation in view of energy conservation. More energy saving may be achieved by providing appropriate arrangement of heat exchanges between sections. The interactive graphical design method to determine the appropriate heat exchange arrangement in a previous paper was developed for a binary system. The design method was extended and applied to a multicomponent system by adopting the idea of a quasi‐binary system. Also, a new HIDiC structure that can realize the outcomes of the proposed design method was developed. The economics of the proposed structure was precisely evaluated through a case study of a commercial scale column. It demonstrated that the proposed structure has attractive economics. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3479–3488, 2015     

具有热集成的甲醇多效精馏新工艺及其模拟

在分析现有甲醇双效精馏工艺存在不足的基础上,提出了一种节能的五塔甲醇多效精馏新工艺.五塔新工艺在现有四塔工艺的加压塔之后增加了1台中压塔,精甲醇按适当比例分别由加压塔、中压塔、常压塔和回收塔塔顶采出,使原加压塔和常压塔负荷减少约30%;同时适当提高了新回收塔的操作压力,使加压塔与中压塔、中压塔与常压塔、回收塔与预塔形成...     

精馏塔设备的设计与节能研究进展

精馏过程是化工过程中最耗能的过程之一。本文总结了常规精馏塔,反应精馏塔以及分隔壁精馏塔这几种类型精馏塔的研究进展。常规精馏塔的研究仍在进行,并主要体现在算法的改进与新算法的提出,以及常规精馏塔在化工高等教学的重要作用上,指出了反应精馏塔和分隔壁精馏塔是近几年精馏塔设计方面的研究热点,如反应精馏塔的模型、求解方法等,分隔壁精馏塔是一种全新的概念因而并未系统化,但却能够明显节省设备投资,并具有良好的节能前景,尤其是在与反应精馏结合后效果特别明显。文章最后对精馏塔的未来研究方向进行了展望。     

数学规划与图形方法相结合设计热集成用水网络

将数学规划法与图形方法相结合探究单杂质用水网络与换热网络的集成问题。首先构建混合整数非线性规划模型（MINLP）,在最小公用工程消耗下优化流股参数未知情况下的分离系统组合曲线面积,得到了最为节能、换热面积最小的用水网络结构。在此基础上,提出了新的分离系统组合曲线演化步骤和规则,可以得到换热单元数目较小的换热网络结构。算例表明,与现有的基于分离系统的热集成用水网络设计方法相比,在最小化公用工程用量的同时可以进一步降低换热器数目与总换热面积。     

Comparison between the design of experiments and simulation in the three-phase distillation in a sieve tray column for glycerine dehydration

Design of experiments (DOE) is a value scientific approach used to understand the processes in a better way and to determine how the inputs affect the response(s). In this work, this method has been applied to study the behavior of the three-phase distillation in a sieve tray column, through the effects of the process and geometrical variables. The experimental values were compared with predicted values obtained by simulation using the equilibrium and nonequilibrium models. Three-phase distillation has been used for glycerine dehydration using toluene as entrainer, in order to avoid the glycerol degradation by distillation at atmospheric pressure. The best conditions found were: vapor flow rate of toluene = 23.5 kg/h, feed flow rate = 2.2 kg/h and feed concentration = 50 wt% glycerol, using the layout L₄ with fractional hole area = 0.04 and weir height = 70 mm. The nonequilibrium model based on Eckert and Vanek's approach (2001) and Chen–Chuang's correlation (1993) have been used to estimate the binary coefficients of mass transport. The predicted values obtained by the experimental model and by the nonequilibrium model have represented the behavior of the dehydration in the sieve tray column studied. Both models underpinned the experimental results obtained for this column.     

Towards further internal heat integration in design of reactive distillation columns—part I: The design principle

The thermodynamic efficiency of a reactive distillation column involving reactions with a highly thermal effect could sometimes be improved substantially through seeking further internal heat integration between the reaction operation and separation operation. Prudent arrangement of the reactive section and deliberate determination of feed location are the two effective methods that can complement internal heat integration within a reactive distillation column. The reactive section is suggested to properly superimpose onto both the stripping section for exothermic reactions and the rectifying section for endothermic reactions. Feed location should be determined so that the effect of internal heat integration can be maximized between the reaction and separation operations. Two reactive distillation systems, involving a highly exothermic reaction and a highly endothermic one, are employed to evaluate the proposed design philosophy and the results obtained confirm its feasibility and effectiveness. In addition, sensitivity analysis is conducted with respect to the amount of catalyst employed, relative volatilities of reacting mixtures, and thermal condition of feeds. The applicability and potentials of the design principle proposed are highlighted.