宽沸程物系分离过程的热集成

针对宽沸程物系分离的特点,研究了热集成以及综合的方法.将浓度从进料到产品分段,每段对应一个精馏塔操作,通过调整各塔的出料浓度、操作压力,实现各塔间的热集成.以年度费用为目标,给出了各塔的分离浓度、操作压力、设备尺寸及热集成方案的编码方法,利用模拟退火算法进行优化,得到年度费用最低的工艺流程.与单塔分离相比,能显著地降低所求问题的操作费用,但随着段数的增加,这种降低的速度变缓.应用结果表明,这种分段集成的方法能够方便地实现所求问题的描述与建模,模拟退火算法能够实现模型的求解.     

联碱氯化铵过程节能途径(上)——提高结晶温度,减少外冷负荷工艺分析

在对两种碳酸化工艺生产使用的氨母液ⅠCNH3浓度,两种母液ⅡNa+浓度,以及不同温度条件下操作的冷析结晶器和盐析结晶器进行物料和热量平衡的基础上,全面分析了有效降低氯化铵制造过程冰机能耗的途径和节能效果。介绍了母液组成设计方法,继建议弃用历来信奉的"盐析温升5℃"概念,对"氨ⅠCNH3高,母液当量小,制铵能耗低"的传统认识,以及逆料流程增加了外冷负荷等说法作了新的诠释。     

醇-水集热共沸精馏模拟研究

研究乙醇、水共沸精馏的热量集成流程。指定塔压使提浓塔冷凝器负荷提供脱水塔再沸釜所需的热量，产物流的热量用以预热提浓塔进料液得以回收。通过模拟计算找出能耗最少的二塔构型流程，表明集热流程是一种有效的节能途径。并对戊烷和苯分别作为夹带剂的结果加以比较。     

加氢裂化装置预闪蒸罐研究

以某工业加氢裂化装置设计数据为基础,考察常压分馏塔进料加热炉前设置预闪蒸罐的必要性以及罐的温度、压力对分馏塔的影响,并对设罐后,闪蒸罐的操作条件对能耗、操作成本及投资方面的影响进行了对比。结果表明：对于以石脑油、航煤、柴油和尾油（作为产品送出装置或者作为循环油返回反应部分）为目标产品的加氢裂化装置,设罐可有效降低进料加热炉和分馏塔的负荷。在相同压力下,闪蒸罐的温度越高,分馏塔负荷越小;在相同温度下,闪蒸罐压力越低,分馏塔负荷越小。在分馏塔输入热量相同的情况下,罐的闪蒸温度高,可节省投资和能耗,闪蒸温度低,可节省操作成本。设计过程中可根据航煤和柴油分离要求的不同,在一定范围内灵活选择闪蒸罐的温度和压力。     

考虑非等温混合的能量集成水网络设计方法

讨论了能量集成水网络中非等温混合对系统能量目标的影响,提出了分割温度的概念。对于同性混合,系统的公用工程需求量不会减少。对于异性混合,通过确定分割温度并比较分割温度以上区间混合流股的热量之和与低温区间所需的热量,可以准确确定系统公用工程会增加、减少或者保持不变。基于以上思想,得到了非等温混合规则。它能判断是否存在能量惩罚,以及如何通过设计混合温度来避免能量惩罚。结合改进的"分离系统"法,提出了一种系统化的能量集成水网络设计方法。     

基于热管传热的盐水真空分离

将热管高效传热和高压喷雾技术应用于单级真空蒸发器,对含盐量3%的人造海水进行试验,结果表明:热管吸收40～80℃的低品位热源热量并以高热通量传递给闪蒸后的液滴,能保持甚至提高液滴蒸发过程的过热度,显著增大水分离率;冷热源温度取代初始过热度成为影响分离效果的主要因素,但要避免干壁现象;改变冷热源温度、初始过热度及流量能实现对分离率的调节。该方法对低品位热源在海水淡化工程中的有效利用、提升单位体积装置淡水产量和制取浓盐水均有重要参考价值。     

基于热管传热的盐水真空分离

将热管高效传热和高压喷雾技术应用于单级真空蒸发器,对含盐量3%的人造海水进行试验,结果表明:热管吸收40~80℃的低品位热源热量并以高热通量传递给闪蒸后的液滴,能保持甚至提高液滴蒸发过程的过热度,显著增大水分离率;冷热源温度取代初始过热度成为影响分离效果的主要因素,但要避免干壁现象;改变冷热源温度、初始过热度及流量能实现对分离率的调节。该方法对低品位热源在海水淡化工程中的有效利用、提升单位体积装置淡水产量和制取浓盐水均有重要参考价值。     

精馏塔理论板上浓度返混对分离效果及能耗的影响——化工原理课程从闪蒸角度对精馏的解释

精馏塔理论板上的气液相接触后进入相临理论板的物流组成通常会偏离平衡组成,带来的浓度返混对分离能力和所需热量具有很大影响。为了便于从能耗和分离效果上进行对比,采用了带回流的多级闪蒸作为常规精馏的等价流程,以气化分率为变量进行研究。通过理论推导及Aspen plus模拟证实带回流多级闪蒸与常规精馏构型的一致性,选用苯-甲苯体系进行模拟研究。研究结果表明,进行精馏操作时若每级进料气、液相间的浓度返混程度越小则分离效果和所需的热负荷越能得到优化。同时得到在保证每级进料气、液相间无浓度返混时各级温度、汽化分率分布的初步规律,为效益高的精馏塔设备的设计提供了目标函数和约束条件。     

组合式干燥系统的分段优化设计方法

提出了分离过程的分段设计法：将一个任务分解为多个子任务,根据各个子任务的不同特点进行设计. 对干燥过程进行优化设计,以年费用最小为目标,将干燥过程表示为最多3段的超结构,每段有2个干燥设备可以选择,给出了单元和过程系统的模型和经济模型. 实例研究结果表明,当物料含水量大于物料在该条件下的临界含水量时,宜采用两段干燥的方法,将回转圆筒干燥器和流化床干燥器组合进行干燥;当物料含水量低于临界含水量时,宜采用一段干燥,将物料直接放入流化床干燥器进行干燥.     

带有中间热集成的精馏塔序列及其性能

提出一种带有中间热集成的精馏塔序列(IHISDC)的流程,针对三组元混合物分离的简单塔直接序列,对该流程进行了分析。与传统热集成精馏序列(HISDC)相比,提出的IHISDC通过中间换热器将高压塔的精馏段与低压塔的提馏段进行局部热集成,使能量集成精馏塔之间的压力差更小,进而使能耗费用下降。同时发现,IHISDC中的高压塔再沸器热负荷和低压塔冷凝器热负荷增加,由于换热器数量的增加,IHISDC的投资费用较大。为了进一步降低IHISDC的年度总费用,需要对其设计参数进行优化。     

考虑内部热集成的乙二醇反应精馏系统设计与优化

针对环氧乙烷水合制乙二醇反应精馏过程反应热的利用和系统能量更大集成问题,提出一种将反应段和提馏段分割、从反应段移出热量供提馏段加热的内部热集成反应精馏塔（R-HIDiC）的设计。利用Aspen Plus模拟软件,分析了内部热集成的可能性,优化了内部热交换量及其分布,给出了一种不需要再沸器的能量最大集成方案。研究表明,与传统的反应精馏塔相比,通过对内部热集成进行优化,乙二醇反应精馏塔可取消再沸器,系统需要的能量只由环氧乙烷水合反应热和外部压缩机提供,其操作费用将降低约47.2%,总费用将降低约39.1%,体现了其技术和经济优越性。     

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.     

Interpreting the dynamic effect of internal heat integration on reactive distillation columns

In this work,the impact of internal heat integration upon process dynamics and controllability by superposing reactive section onto stripping section,relocating feed locations,and redistributing catalyst within the reactive section is explored based on a hypothetical ideal reactive distillation system containing an exothermic reaction:A + B ←→ C + D.Steady state operation analysis and closed-loop controllability evaluation are carried out by comparing the process designs with and without the consideration of internal heat integration,For superposing reactive section onto stripping section,favorable effect is aroused due to its low sensitivities to the changes in operating condition,For ascending the lower feed stage,somewhat detrimental effect occurs because of the accompanied adverse internal heat integration and strong sensitivity to the changes in operating condition.For descending the upper feed stage,serious detrimental effect happens because of the introduced adverse internal heat integration and strong sensitivity to the changes in operating condition.For redistributing catalyst in the reactive section,fairly small negative influence is aroused by the sensitivity to the changes in operating condition.When reinforcing internal heat integration with a combinatorial use of these three strategies,the decent of the upper feed stage should be avoided in process development.Although the conclusions are derived based on the hypothetical ideal reactive distillation column studied,they are considered to be of general significance to the design and operation of other reactive distillation columns.     

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.     

Simulation and process integration for tert-amyl-methyl ether (TAME) synthesis

This paper proposes an extended approach to develop a new sustainable process to produce tert-amyl-methyl ether (TAME) using as feedstock enriched C₅ fraction (LCN – light cracking naphtha) from fluid catalytic cracking (FCC). To the best of our knowledge, up to now, different authors developed the separation section without considering all possible options. The main contribution is to bring together for comparison different separation techniques of the given mixture and to develop new configurations for the separation section of the plant. In this respect, pressure swing is combined with liquid–liquid separation. Existing technologies consider methanol (MeOH) separation from reactor effluent only by water extraction, combined with distillation. Conceptual design based on residual curve maps (RCM) analysis, considered in this paper, reveals new possibilities to use pressure swing, eventually combined with liquid–liquid separation. Thus, compared to other results reported in literature, new separation sequences are proposed for TAME synthesis reactor effluent separation, in the frame of an extended and detailed analysis for the whole process.To underline process characteristics, three case studies, with those different configurations are presented and analysed using Aspen HYSYS^® v8.4. Main details are obtained using process simulation, process integration and environmental impact computer tools. In the first case study, classical MeOH separation using water extraction is considered. The second case study is based only on pressure swing distillation to separate the azeotropes between hydrocarbons and methanol. In the third case study, pressure swing distillation is combined with separation based on hydrocarbon–methanol liquid–liquid phase equilibrium. Using process simulation results, setup with Aspen HYSYS^® v8.4, heat integration analysis, performed with SPRINT^® v2.8, is accomplished to exploit energy savings. Environmental impact calculations are performed using WAR algorithm, considering different fuel types for utilities generation. Results show that the elimination of water in separation section and the use of liquid–liquid phase separation ensure lower energy consumption (overall heat recovery in case study 3 is 9.87 MW, compared to 7.47 MW for case study 2) and better environmental performance. Economic indicators calculated with Aspen Process Economic Analyzer^® allow identification of attractive process changes, for the new proposed process configuration.     

Analysis of IgG heavy chain to light chain ratio with mutant Encephalomyocarditis virus internal ribosome entry site

Immunoglobulin G (IgG) is a heterotetrameric protein assembled from two identical heavy chain (HC) and two identical light chain (LC) polypeptides. The HC and LC folding and assembly are a crucial step for IgG production. It is affected by the ratio of HC to LC expression (HC:LC). To date, the HC:LC ratio was analysed mainly by cotransfection of different amounts of two monocistronic HC and LC expression plasmids, an approach biased by different transfection efficiencies. To circumvent this problem, a series of Encephalomyocarditis virus internal ribosome entry site (EMCV IRES) variants with different translation efficiencies were created and used to mediate HC translation in bicistronic constructs. HC and LC were translated from the same mRNA, which provides a more accurate method for the evaluation of the optimal ratio of HC:LC. The results show that the IgG optimal expression levels were obtained when the IRES mediated translation efficiency of the HC was about 50% compared to the cap-dependent translation of the LC. A surprisingly sharp transition to low production was shown when the ratios were below 40%. This study provides a new method to investigate the production of heterodimeric proteins in mammalian cells and adds understanding to the mechanisms of IgG folding and assembly.     

外部热耦合复合精馏塔的经济性与可控性评价

外部热耦合复合精馏塔系统是一种新型的精馏塔系统,通过操作在不同压力下的两个精馏塔的精馏段和提馏段之间的热传递来提高热力学效率。根据精馏段和提馏段热耦合的相对位置不同,外部热耦合复合精馏塔系统可分为对称型和非对称型两种结构。为便于设计和实现,可用外部换热器替代外部热耦合得到简化的结构。本文以乙烯乙烷物系分离过程为对象,通过对外部热耦合复合精馏塔系统建立了静动态模型,采用四点控制的方法,对三种结构的外部热耦合复合精馏塔的经济性和可控性两方面做了分析,证明了非对称型优于对称型外部热耦合复合精馏塔。同时,对使用外部换热器简化外部热耦合结构的方法提供了理论依据和参考。     

热集成变压精馏分离乙二胺-水共沸体系的模拟优化

针对乙二胺-水共沸物组成对压力较为敏感的特性,采用部分热集成变压精馏工艺分离该共沸物。先利用Aspen Plus软件对该工艺进行稳态模拟,再以理论塔板数、进料位置、回流比为优化变量,水和乙二胺的纯度为约束,以年度总费用（total annual cost,TAC）为目标函数建立乙二胺-水共沸体系分离系统的优化设计模型。采用列队竞争算法对该分离过程主要工艺参数进行优化,得到了变压精馏分离乙二胺-水体系的最佳工艺操作参数及设备参数。模拟结果表明,利用算法对多变量进行同时优化可得到更具经济效益的分离系统,与传统优化结果相比,可降低TAC约7.31%。在此基础上,对高压塔的操作压力进行优化分析,将其由2atm提升至4atm（1atm=101325Pa）,并对流程其他参数进行优化,可显著降低TAC约24.62%。进一步,采用部分热集成比普通变压双塔精馏降低TAC约21.87%     

Process integration technology review: background and applications in the chemical process industry

Process integration is a holistic approach to process design and operation which emphasizes the unity of the process. Process integration design tools have been developed over the past two decades to achieve process improvement, productivity enhancement, conservation in mass and energy resources, and reductions in the operating and capital costs of chemical processes. The primary applications of these integrated tools have focused on resource conservation, pollution prevention and energy management. Specifically, the past two decades have seen the development and/or application of process integration design tools for heat exchange networks (HENs), wastewater reduction and water conservation networks, mass exchange networks (MENs), heat‐ and energy‐induced separation networks (HISENs and EISENs), waste interception networks (WINs) and heat‐ and energy‐induced waste minimization networks (HIWAMINs and EIWAMINs), to name a few. This paper provides an overview of some of these developments and outlines major driving forces and hurdles. The fundamental aspects of this approach along with their incorporation in an overall design methodology will be discussed. The paper also highlights several recent applications of process integration to industrial processes. Copyright © 2003 Society of Chemical Industry