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。     

内部热耦合反应精馏塔塔构型的研究

以乙酸甲酯水解为例,利用模拟软件Aspen Plus建立了内部热耦合反应精馏塔模型,研究了内部热耦合反应精馏塔各种可能塔构型的节能效果,并且在相同的产品要求和最小传热温差下对内部热耦合反应精馏塔各构型的能耗进行了对比。结果表明,塔构型对乙酸甲酯水解的内部热耦合反应精馏流程的操作性能有重要的影响,并且存在最佳构型。其最佳构型的特征为,反应段全部在内部热耦合反应精馏塔的精馏塔内且精馏塔与提馏塔中理论板均参与传热的塔构型。     

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。     

内部热耦合精馏塔节能特性研究

以苯-甲苯作为分离物系,对内部热耦合精馏塔进行模拟计算。模拟结果表明内部热耦合精馏塔的温度及液相流率分布等特性与传统精馏塔存在较大差异,分析讨论了压缩比对内部热耦合精馏塔特性的影响。文章对精馏装置节能改建具有重要指导意义。     

内部热耦合精馏塔的传热及优化

为研究同轴式内部热耦合精馏塔（HIDiC）在不同压缩比下的传热量和传热系数,以乙醇-水为分离物系,在自制中试装置中进行了实验研究。建立了同轴式HIDiC的传热模型即利用闪蒸罐代替塔板,计算进出闪蒸罐物流的焓值差,从而得到精馏段与提馏段板间换热量,并通过划分区域的方法计算了传热系数。以年度总费用（TAC）作为优化指标研究了实现外回流为零时所需的外部换热器的个数。结果表明：当压缩比为2.2时,塔间传热量最大,冷凝器和再沸器的负荷最低,且压缩比与传热系数的关系为负相关;随着精馏段与提馏段板间最小换热温差的增大,所需外部换热器个数不断减少,TAC呈现降低的趋势,当外部换热器个数为1,即热量耦合位置为精馏段第一块板与提馏段第一块板时,TAC最低。     

热耦合精馏工艺的模拟

为了进一步了解热耦合精馏工艺的适用范围,同时寻找其中经济性较优的工艺流程,本文利用Aspen Plus流程模拟软件,针对相对挥发度依次递增的四组二元物系(苯-氟苯、苯-正庚烷、苯-甲苯、苯-氯苯)分别开展了常规精馏和4种热耦合精馏工艺(热泵精馏塔、理想内部热耦合精馏塔、内部热耦合精馏塔简化构型、差压热耦合精馏塔)的模拟研究,过程优化的目标函数为年均总费用最低。通过优化结果的对比可知,热耦合精馏工艺在分离相对挥发度较小的物系时能耗相对较低,经济性相对较好,其中又以热泵精馏塔和差压热耦合精馏塔的效果最为显著;而在相对挥发度较大的物系分离中,常规精馏则是较为合适的工艺选择。此外,随着投资回收期的减小,热耦合精馏工艺相对于常规精馏工艺的优势也有所下降。     

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。     

内部热耦合反应精馏塔内乙酸甲酯的合成研究

提出了一种应用内部热耦合反应精馏技术合成乙酸甲酯的新工艺流程,即采用内部热耦合反应精馏塔替代常规流程中的反应精馏塔。利用Aspen Plus模拟软件对新工艺流程及常规流程做了模拟分析,比较分析了2种工艺流程塔内气液相组成分布、塔内温度分布,并考察了压缩机压缩比对新工艺的影响。结果显示,新工艺流程比常规反应精馏流程节能44.51%,而且新工艺能大幅度地减少CO2排放量。     

乙酸戊酯反应精馏塔强化内部物质耦合的综合与设计

乙酸戊酯反应属于无热反应,由于反应热很小,反应段与精馏段的内部热耦合的作用对于系统的影响也是可以忽略的。热力学效率可以通过强化反应段和分离段的内部物质耦合来大大的提高[1]。本文中,乙酸戊酯反应精馏塔的优化方法包括反应段与精馏段的耦合,反应段与提馏段的耦合,进料位置的再定位,以及催化剂的重新分布,通过四种强化方法的结合,最终实现无热反应精馏塔静态性能的大幅度优化[2]。     

风冷热泵用新型干式蒸发器的实验研究

针对传统折流板管壳干式蒸发器存在换热性能不佳和阻力大的问题,基于非对称空间传热理念,提出一种新型顺紊流自支撑型干式蒸发器,并将其装配在风冷热泵上进行实验测试研究。测试结果表明:风冷热泵的制冷量为52.33k W,制冷性能系数为2.47,制热量为63.32 k W,制热性能系数为3.0。实验对比配置传统折流板管壳干式蒸发器的同型号风冷热泵,其干式蒸发器的换热面积减少33.3%,制冷性能系数提高6.0%,制热性能系数提高15.8%,制冷剂充注量减少7.1%。     

Comparison of Energy Usage for the Vacuum Separation of Acetic Acid/Acetic Anhydride Using an Internally Heat Integrated Distillation Column (HIDiC)

Abstract

Energy savings for an internally heat-integrated distillation column (HIDiC) and a vapor recompression column for the vacuum separation of acetic acid/acetic anhydride was theoretically analyzed and compared to the simulation of a reference column configuration of the Eastman Chemical Company using ASPEN Plus. In these simulations, the design and operating variables were defined and optimized to minimize total energy used. The effects of design variables such as quantity and location of the heat integration stages, reflux ratio, and rectifying section absolute pressure on energy consumption and product purity revealed that one HIDiC configuration had 62% energy savings over the reference column. The distillation column using vapor recompression was evaluated as a benchmark for comparing the HIDiC configurations and the reference column. The VRC column simulation predicted both increased product purity and an energy savings of 91% over the reference unit.     

A review of internally heat integrated distillation column

The energy consumption of distillation operation determines the amount of energy consumption throughout the chemical separation process. A heat integrated distillation column(HIDiC) could greatly reduce the irreversibility of the distillation process, so it gradually becomes a research hotspot. There are two major techniques for heat integration in HIDiC: internally and externally. This review paper describes the major research aspects of an internally heat integrated distillation column(IHIDiC), including the heat transfer models, various design structures(including the two-column HIDiC, Concentric HIDiC, Shell and tube HIDiC, Plate-fin HIDiC and the Super HIDiC, etc.), experimental research, simulation and optimization, process control research, as well as industrial plants and potential industrial applications. Among them, the heat transfer performance of various structures was analyzed of the various design structures based on experimental research, the effects of different factors(including relative volatility, reflux ratio, compression ratio, etc.) on HIDiC energy consumption or TAC is summarized in the simulation part. The calculation methods of the overall heat transfer coefficient and heat transfer models are summarized. The various optimization algorithms and optimization results of simplified HIDiC are summarized in the optimization part. The research status and the key technical issues in various aspects of HIDiC are summarized in this paper. In order to meet the requirements of industrial energy efficiency,the selection of multi-component separation distillation configurations needs to be considered more diversified,and internal complex coupling relationship of HIDiC needs to be further studied.     

基于塔总组合曲线的内部热耦合精馏塔优化设计方法

基于塔总组合曲线（CGCC）,提出了一种简化内部热耦合精馏塔（HIDiC）结构的图形设计方法。在完成精馏段（或提馏段）单塔段中间换热器优化设置的基础上,结合精馏段与提馏段CGCC的集成图,以HIDiC的可减小过程总（火用）损为目标,确定HIDiC热耦合中间换热器的最优设计。以苯乙烯-乙苯HIDiC为例,计算结果表明,设置中间换热器后,HIDiC可减小过程总（火用）损最大值为1.951 MW,HIDiC的冷凝器、再沸器负荷分别下降63.6%和68.4%;热耦合中间换热器分别设置于精馏段第2、12、和38块塔板,提馏段第20、28和36块塔板,热负荷依次为0.841、1.496和2.053 MW。     

同轴式内部热耦合精馏塔的传热性能

提出了一种以实验物系的物性数据为基础的计算同轴式内部热耦合精馏塔（HIDiC）总传热系数的方法。本文以乙醇-水为实验物系,以自行搭建的中试规模同轴式HIDiC为研究对象,通过在不同压缩比下（1.4~2.6,步长为0.1）的连续操作实验研究,得到塔内的温度分布,通过计算两塔段的相变给热系数来计算该塔的总传热系数和精馏塔段与提馏塔段间的换热量。在同轴式HIDiC中乙醇-水实验物系总传热系数的计算值在300~800W/(m²·K),并且随着压缩比的增大而逐渐降低。在操作条件和产品纯度与实验值保持一致的情况下,将精馏塔段与提馏塔段间换热量的计算值带入软件中模拟,得到的全塔温度分布与实验中的温度分布在误差范围内吻合良好,证明本文计算同轴式HIDiC总传热系数的方法切实有效。     

A review on process intensification in internally heat-integrated distillation columns

Internally heat-integrated distillation column (HIDiC) is the most radical approach of a heat pump design, making efficient use of internal heat-integration: the rectifying section of a distillation column operating at a higher pressure becomes the heat source, while the stripping part of the column acts as a heat sink. Remarkably, a HIDIC can bring up to 70% energy savings compared to conventional distillation columns. This is highly appealing regarding the fact that distillation is one of the most energy intensive operations in the chemical process industry accounting for over 40% of the energy usage. This review paper describes the latest developments concerning this promising but difficult to implement process intensification technology, covering all the major aspects related to the working principle, thermodynamic analysis, potential energy savings, various design configurations and construction options (ranging from inter-coupled or concentric columns, shell and tube and plate–fin heat exchanger columns to SuperHIDiC), design optimization, process control and operation issues, as well as pilot-scale and potential industrial applications. Further advancement, i.e., development of HIDiC technology for multi-component mixture separations is an extremely challenging research topic, especially when HIDiC becomes associated with other technologies such as dividing-wall column (DWC) or reactive distillation (RD).     

通用热耦合精馏塔的制控系统的评估

The assessment of control configurations for an ideal heat integrated distillation column incorporated with an overhead condenser and a bottom reboiler (general HIDiC) is addressed in this work. It is found that double ratio control configuration, (L/D, V/B), is still the best one among all the possibilities. The control configuration,(Pr - Ps, q), appears to be a feasible one for the general HIDiC and the pressure difference between the rectifying and the stripping sections and feed thermal condition are expected to be consistent manipulative variables for the process. The performance of the general HIDiC can be substantially improved by employing effective multivariable control algorithms.     

Reversibility Analysis for Design Optimization of an Internally Heat‐Integrated Distillation Column

Internally heat‐integrated distillation columns (HIDiCs) need heat transfer between the two column sections. Intermediate condensing and reboiling of the rectifying and stripping sections favor the reversibility of the separation process and lead to the increase of heat loads for the two sections but the heat transfer to cover the heat load is costly and generates major difficulties in design. A higher number of stages can reduce the heat load but will also raise the investment cost. The influence of increasing stage numbers on operating cost and capital investment of the HIDiC was evaluated by two HIDiC design cases, and the stage numbers or equivalently the heat loads were optimized to achieve the balance between the two kinds of cost.