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We have designed a separation process of isobutyl alcohol (52.0 mol%) and isobutyl acetate (48.0 mol%) mixture using conventional extractive distillation (ED) and extractive dividing‐wall column (E‐DWC) with the solvent dimethyl sulfoxide (DMSO). The binary mixture exhibits a minimum boiling azeotrope that is sensitive to pressure. Thermodynamic analyses have shown that the vacuum pressures work better compared to the atmospheric pressure when DMSO is the solvent. Based on the separation with a purity of 99.9 mol%, the E‐DWC process has resulted in 9.6 % and 4.8 % reductions in the total annual cost and CO2 emission rates, respectively, in comparison to the conventional method. After further intensification using the heat pump technique, the E‐DWC process with the solvent DMSO has provided more than 40.0 % reduction in energy consumption compared to the ED systems studied in the literature using the solvents butyl propionate and dimethylformamide. [ABSTRACT FROM AUTHOR]

A thermally coupled distillation technology can bring energy‐saving benefits, but it poses challenges to process control. This article explores dynamic control of different side‐stream quaternary extractive distillation configurations. One the one hand, the open‐loop controllability of these processes is analyzed in terms of various criteria by the control design interface technology of Aspen Plus Dynamics. On the other hand, their control structures are established and examined by introducing large feed flow and composition perturbations. The results show that the triple‐side‐stream distillation still performs the best state and input–output controllability in spite of the strongest nonlinearity, and is also well resistant to large feed perturbations using a simple control structure. [ABSTRACT FROM AUTHOR]

Controllability features of the extractive distillation process and the pressure‐swing distillation process were studied with dynamic tools and compared in the case study of separation of a mixture of 50 mol % tetrahydrofuran and 50 mol % water. Process simulations with Aspen Plus and Aspen Plus Dynamics were carried out to obtain 99.9 mol % product purity. Control structures for the two distillation techniques were determined. Load rejection studies were completed for ±10 % feed throughput and ±10 % feed composition disturbances, for both processes. The comparison of the dynamic responses, integral absolute errors, and integral square errors shows that the pressure‐swing distillation process has better controllability features than extractive distillation. [ABSTRACT FROM AUTHOR]

There are three kinds of binary azeotropes and one kind of a near‐boiling compound with clamping zone characteristics in the triethylamine‐dichloromethane‐acetone‐water system, which belongs to complex quaternary systems. A four‐column distillation process of heterogeneous azeotropic extraction for the separation of the system was designed, simulated, and optimized to obtain more suitable process parameters and energy consumption distribution of each column. On this basis, taking the total annual cost (TAC) as the comprehensive economic evaluation index and CO2 emission as the environmental evaluation index, the thermal integration technology and mechanical vapor recompression (MVR) heat pump technology were applied to the energy‐saving research of the distillation process for the system. The results indicate that compared with the conventional four‐column heterogeneous azeotropic extractive distillation process, the thermal integration distillation process and single‐column MVR heat pump coupled thermal integration distillation process can save energy consumption and TAC, and it can reduce CO2 emission. [ABSTRACT FROM AUTHOR]

To separate propylene from propane, whose boiling points are very close, leads to challenges, especially if it is intended to achieve higher energy efficiencies, reduce process expenses, and diminish environmental impacts. Polymer‐grade propylene can be obtained through an extractive distillation process, using 90 wt % of acetonitrile (ACN) as main solvent and 10 wt % of ethylenediamine (EDA) or methyl ethyl ketone or ethanol as co‐solvent, favoring the separation of propylene with purity greater than 99.60 mol % due to the increase of the relative volatility of propane. Compared to the use of aqueous N‐methyl‐2‐pyrrolidone (NMP) as extraction solvent, ACN‐EDA solvents have shown to be able to achieve savings of 8.09 % in total annual cost and 5.95 % in CO2 emissions. The results demonstrate that the extractive distillation process using ACN‐EDA can reduce process costs as well as CO2 emissions compared to the same process with aqueous NMP. [ABSTRACT FROM AUTHOR]

The separation requirements of the ethanol‐tert‐butanol‐water system are difficult to meet due to the formation of azeotropes under normal pressure. After screening the four most important ionic liquids, i.e., [BMIM][BF4], [EMIM][Cl], [HMIM][Cl], and [EMIM][AC], ionic liquid [EMIM][AC] was selected as extractant, and quantum chemical calculations based on COSMO‐SAC theory were carried out to analyze the mechanism of the separation process. An ethanol‐tert‐butanol‐water extractive distillation process was designed, optimized with the goal of the lowest total annual economic cost, and the cost of carbon dioxide emissions was calculated. To further save energy, a heat pump distillation process was designed and compared with the conventional ionic liquid process. The annual total cost of the heat pump distillation process is reduced by 10.11 %, and carbon dioxide emission costs are reduced by 61.9 %. Comparison with the conventional extractive distillation process and its modified process revealed economic advantages for the ionic liquid extractive distillation process and its heat pump version. [ABSTRACT FROM AUTHOR]

The separation of polymer‐grade propylene from a propylene‐propane mixture was performed by an extractive distillation (ED) process in the steady state, and was developed on the Aspen Plus V9 simulator, by using an extractive column and a recovery column. To increase the volatility and relative selectivity of propylene, aqueous N‐methyl‐2‐pyrrolidone (NMP) was used as extracting agent. By using an ED process and aqueous NMP, compared with the high‐pressure binary distillation process, a reduction in energy consumption was obtained, with a saving of 52 % in total annual cost. [ABSTRACT FROM AUTHOR]

Extractive distillation is one of the energy‐efficient methods for separating azeotropic mixtures. The question of the influence of the mixture original composition on the operating parameters of the columns of extractive and auto‐extractive distillation remains open. The extractive distillation of an acetone+methanol mixture and auto‐extractive distillation of an acetone+methanol+water (dimethylsulfoxide) mixture was simulated using AspenPlus. The impact of the solvent and acetone content in the original mixture on the operating parameters of the columns was investigated for the first time. It is demonstrated that the presence of an entrainer in the original mixture reduces the amount of solvent needed to separate the mixture, the reflux ratio, and the total energy consumption of the process. [ABSTRACT FROM AUTHOR]

Due to its high reactivity, monochloroacetic acid (MCA) is an essential intermediate used in the manufacturing of a wide variety of chemicals. Its industrial production process is highly energy‐ and capital‐intensive, requiring costly purification steps to remove dichloroacetic acid (DCA) impurities. Here, an innovative eco‐efficient process for MCA‐DCA separation is proposed based on extractive distillation in a fully thermally coupled system (a dividing‐wall column (DWC) or an equivalent side‐rectifier configuration) using a new effective solvent: diethylene glycol dipentylether. The design was optimized by performing sensitivity analyses and varying key operating and design parameters. The study proves that separating MCA‐DCA by an extractive DWC (or thermally coupled) is feasible, efficient, controllable, economic, and sustainable. [ABSTRACT FROM AUTHOR]

Methyl ethyl ketone (MEK) is widely used in the industry and is mainly produced from petroleum. Some works have projected MEK as a possible fuel since its performance in spark engines has overcome the performance of gasoline in certain indexes. Two intensified alternatives to produce MEK are introduced here, consisting of a reactive distillation column, an extractive distillation column, and three conventional distillation columns. The direct alternative resulted as the most promising when it was evaluated based on energy consumption, greenhouse gas emissions, and an environmental index. The obtained energy consumption for MEK production was 11.62 MJ kgMEK−1 for the entire process. Moreover, those intensified alternatives showed better performance indexes in comparison with a conventional process. [ABSTRACT FROM AUTHOR]

An extractive distillation process with two columns and a decanter was proposed to separate ternary toluene‐methanol‐water azeotropic mixtures in a previous study. Based on this process, six processes were established to explore further energy‐efficient schemes to separate the ternary azeotropic system. The optimal parameters of the process were determined in terms of the minimum total annual cost (TAC). The processes with heat integration perform better than those with a side stream or thermal coupling in terms of energy savings and TAC reduction. A process in which both the feed stream of the extractive distillation column and the entrainer recovery column are preheated by the entrainer recycle stream can reduce energy consumption by up to 27.69 % and TAC by 21.36 %. [ABSTRACT FROM AUTHOR]

As cracker feed around the globe is trending towards lighter feedstocks, butadiene production facilities worldwide are now run at turndown capacities. Models are developed to study how operation at turndown ratios of feed rates affects the purity of 1,3‐butadiene. The optimal solvent‐to‐feed ratio was found to be in the range of 6–7 when the plant is run at normal throughput; however, it is necessary to change the solvent‐to‐feed ratio in the range of 10–11 when the plant is operating at turndown capacity. Dynamic simulations indicate that the effect of fluctuations in the feed flow rate on product purity can be minimized by a ratio controller to change the solvent flow rate and a composition controller to alter the side‐draw flow rate. [ABSTRACT FROM AUTHOR]

Abstract: Extractive distillation is an alternative for processes where normal distillation is difficult, such as separation of close‐boiling mixtures, but solvent selection for distillation is laborious, and its selection pool is narrow. An innovative selection process using molecular simulation is proposed, and the performance of the selected solvent, 1,2,4‐trichlorobenzene, for the separation of 1,2,4‐trimethylbenzene from a C9 mixture is reviewed. The proposed process requires less investment and leads to lower operating expenses than the conventional two‐column process. The computed vapor‐liquid equilibrium determined from the molecular simulation is close to the HYSYS estimation in two ternary systems. [ABSTRACT FROM AUTHOR]

The binary mixture of n-heptane and isobutanol forms an azeotrope at atmospheric pressure, with a composition of 66.9 mol % n-heptane and a temperature of 364 K. Several methods of separation are possible. This study compares the steady-state economics and the dynamic controllability of three alternative separation techniques: a two-column extractive distillation process, a two-column pressure-swing distillation process, and a single column with a refrigerated condenser. [ABSTRACT FROM AUTHOR]

The extractive distillation process for the separation of an ethyl formate-ethanol-water mixture with ethylene glycol as the extractive solvent was investigated. High-purity products could be gathered in the top of the column, and ethylene glycol could be completely recycled in the bottom of the recovery column. Two kinds of control strategy were designed and tested in the extractive distillation system to handle strong disturbances in feed flow rate and feed composition. A comparison of the results indicated that the control strategy based on a proper variable pairing defined according to the effective relative gain array could more efficiently minimize the dynamic disturbances. [ABSTRACT FROM AUTHOR]

Hydrodistillation of essential oils from leaves of myrtle, rosemary, and sour orange was experimentally studied and the extraction process was modeled. A mass balance was carried out over an assumed flat leave particle and the use of Fick's second law of diffusion led to the mass transfer equation. Its resolution required adequate boundary and initial conditions. The model considered the effect of the main processing parameters on the overall essential oil extraction efficiency as well as the determination of the optimum conditions. To assess the reliability of the model, yield curves for all studied conditions and variation of the oil composition with time were compared with the experimentally obtained results for each plant leave. The agreement seems to be reasonable, although some refining of the model is necessary by taking into account both the diffusion and reaction contributions. [ABSTRACT FROM AUTHOR]

Extractive distillation of ethanol dehydration using glycols as entrainers is proposed. Specifically, ethanol dehydration of an azeotropic mixture in the presence of ethylene glycol + glycerol mixture is evaluated. Simulation is performed and the vapor-liquid equilibrium of ethanol + water + ethylene glycol + glycerol is predicted with the NRTL model. Minimization of energy consumption in both extractive and regeneration columns is attempted. Optimal operating parameters of the process including glycol concentration in the solvent mixture, main feed, and entrainer feed trays, total number of theoretical trays, and heat supplied to the reboiler are determined in order to achieve a specified distillate purity of 99.9 mol % ethanol. [ABSTRACT FROM AUTHOR]

Design and control of an extractive distillation system for tetrahydrofuran (THF) dehydration with ethylene glycol as entrainer is investigated. The main module is a two-column system containing an extractive distillation column, whose top stream is the desired product THF, and an entrainer recovery column. Economic analysis with total annual cost as the objective function is developed. Two kinds of control strategies are explored for THF dehydration. The responses reveal that the control structure with fixed reflux ratio cannot maintain the bottom liquid level of the entrainer recovery column, while the control scheme with fixed reboiler heat duty/feed flow ratio exhibits good control performance in spite of large deviations in feed flow rate and feed composition. [ABSTRACT FROM AUTHOR]

Chemical process simulation software is adopted to simulate the separation of ethyl acetate-dichloromethane-ethanol and water with the aim to use water as the extraction solvent and to meet the requirement of reuse. The influences of solvent ratio, reflux ratio, theoretical plate number, feed position, and solvent position on separation efficiency are discussed. Optimization of orthogonal design and response surface are employed to further optimize the parameters. Relative experimental results prove the reliability of the simulation. [ABSTRACT FROM AUTHOR]