隔板式反应精馏技术的研究进展

隔板式反应精馏技术是一种将隔板式精馏塔和传统反应精馏工艺相结合,反应和分离过程高度强化的复杂技术。简要介绍了隔板式反应精馏技术的特点,并重点论述了该技术在国外的应用以及控制和优化的方法,概述了隔板式反应精馏塔在国内的发展现状,最后指出该技术在节能减排的大环境下将有非常大的发展前景和应用价值。     

Numerical scrutinization of dropwise condensation heat transfer on an inclined surface

Recently, achieving an ameliorated heat transfer rate in dropwise condensation (DWC) has attracted the attention of many researchers. Several parameters, including chemical and physical properties of the substrate, inclination, and interfacial characteristics influence DWC heat transfer rate. The variation of inclination angle is followed by the change in droplet shape and consequently, the heat transfer rate are changed. In this study, the effect of droplet shape variation on diverse inclined substrates is simulated. Moreover, three-dimensional mass, momentum, and energy equations considering the desired boundary conditions on the unstructured grid are utilized for the scrutinization of flow behavior and heat transfer for static and sliding droplets. For the sake of validation, the outcomes obtained from the simulation were compared with existent data in the literature and a proper agreement was attained. Regarding the outcomes, it was of concern that the influence of inclination angle on the droplet shape is more distinct at higher droplet volume; while no considerable change was seen on heat flux of small droplets by increasing the inclination angle. Furthermore, a higher heat transfer rate was noted by exceeding the inclination angle beyond a definite angle. Additionally, the increased heat transfer rate was affirmed by increasing the Marangoni number $\left(\mathit{Ma}\right)$.     

Techno-economic evaluation of top,middle, and bottom divided wall column configurations for benzene,toluene, and xylene processing in aromatic production plant

Divided wall column (DWC) configurations were simulated and optimized for five different feed’s compositions to demonstrate the effect of feed composition and location of dividing wall in DWC in optimum operating conditions, energy requirement, operating, capital and total annualized cost (TAC) to produce market-grade benzene, toluene, and xylene. Operating conditions and cost for each DWC strongly depend on feed composition. Middle DWC (M-DWC) requires significantly lower energy compared with top and bottom DWCs except for feed dominated with xylene where energy requirement is comparable in studied configurations and M-DWC seems the best for ternary mixture separation.     

From laboratory experiments to simulation studies of methanol dehydration to produce dimethyl ether reaction—Part II: Simulation and cost estimation

The vapor phase dimethyl ether (DME) synthesis is simulated by Hysys process simulation software and relevant cost analysis is also conducted. Based on cost estimation results, it is found that capital investment of the classic DME process is greatly influenced by the distillation towers and operating costs. Accordingly, to solve these problems an innovative DME process based on a top-wall dividing-wall column (DWC) in vapor phase is proposed, in this work. It is shown that the novel proposed DWC process leads to 44.53% reduction in operating costs compared to the conventional one, while both schemes predict almost the same output specifications.     

A systematic method to synthesize all dividing wall columns for n‐component separation: Part II

We present a simple rule that, for the first time, enables exhaustive enumeration of dividing wall columns (DWCs) corresponding to any given thermally coupled distillation column‐configuration. With the successive application of our rule, every partition in a DWC can be extended all the way to the top and/or to the bottom of a column without losing thermodynamic equivalence to the original thermally coupled configuration. This leads to easy‐to‐operate DWCs with possible control/regulation of each and every vapor split by external means. As a result, we conclude that any given DWC can be transformed into a thermodynamically equivalent form that is easy‐to‐operate, and hence, there always exists at least one easy‐to‐operate DWC for any given thermally coupled distillation. Our method of enumerating and identifying easy‐to‐operate DWCs for an attractive thermally coupled configuration will contribute toward process intensification by providing ways to implement efficient and low‐cost multicomponent distillations. © 2017 American Institute of Chemical Engineers AIChE J, 64: 660–672, 2018     

拼接式隔板精馏塔的工业应用

介绍了国内自主研发的隔板精馏塔技术在某炼油厂重芳烃油分离过程中的应用情况以及一种传统精馏塔改造为隔板精馏塔的技术。工业应用情况表明:采用拼接式隔板精馏塔改造技术可以实现将传统精馏塔改造为隔板精馏塔;隔板精馏塔可以替代传统的两塔分离流程并同时获得3个产品;隔板精馏塔分离精度高,各个产品之间干点和初馏点温度相差1℃且满足产品质量指标要求。和原有两塔流程相比,可以节省1个塔、1台冷凝器、1台再沸器、1台泵,塔顶冷却水消耗减少31%,塔底蒸汽消耗减少38%,节能效果显著。     

垂直双隔板隔壁塔分离四组分的模拟优化和实验研究

提出了一种垂直双隔板的分离四组分混合物的隔壁塔,对该塔的结构设计进行了详细的介绍和说明,根据新型隔壁塔的塔板结构和分离原理设计了该种塔板的五塔模型并进行了简洁计算。针对烃类体系四组分分离的完全热耦合过程,通过化工流程模拟软件Aspen进行了模拟优化和用能分析,相比一般的序列塔分离工艺,节能最高可达18.6%,节能效果明显。根据工艺模拟结果,以分离戊烷、己烷、庚烷、辛烷为研究对象,对新型塔板进行了小试研究。研究结果表明：影响新型隔壁塔温度分布的主要因素是液相分配比,可通过控制新型隔壁塔主塔段二塔顶冷凝器的回流量来控制主塔段二的温度分布。研究为隔壁塔气相分配的工业化提供了理论依据和设计参考。     

热偶精馏技术与应用进展

热偶精馏比常规精馏流程节能30%,还可降低设备投资。其中的分隔壁精馏塔已有40座以上工业化。本文介绍了热偶精馏的各种流程、节能原理、适用范围。同时介绍了热偶精馏的设计方法及工业应用现状,并对分隔壁精馏塔的应用前景进行了展望。     

Optimal retrofit of a side stream column to a dividing wall column for energy efficiency maximization

A side distillation column is widely used to separate multicomponent mixtures into three products. However, this kind of column consumes considerable amounts of energy due to thermodynamic restrictions and the nature of the distillation process. Retrofit of the side distillation column to a dividing wall column (DWC) can result in significant energy savings. This study evaluated a systematic method for optimal retrofit of a side stream column to a DWC. The minimum energy requirement for the separation of a multicomponent mixture was used for a feasibility study. Subsequently, design and optimization was performed using shortcut, rigorous and response surface methodology. One case study was illustrated to demonstrate the proposed methodology. The results showed that the optimal retrofit of a side distillation column to the DWC could not only save a significant amount of energy, but also increase the capacity. This study highlights the potential for retrofitting a side stream column to a DWC from a techno economic point of view.