Design of hybrid distillation and vapor permeation processes

doi:10.1016/0376-7388(94)00216-L

Journal of Membrane Science

Volume 102, 15 June 1995, Pages 21-30

https://doi.org/10.1016/0376-7388(94)00216-L Get rights and content

Abstract

An explicit algebraic design model for vapor permeation systems is presented. The model is valid for binary mixtures, and is based on a black-box representation of the transport properties across the membrane. Based on this design model, some of the trade-offs in a hybrid distillation and vapor permeation process are illustrated through parametric studies.

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Cited by (32)

Methodology for design of vapor permeation membrane-assisted distillation processes for aqueous azeotrope dehydration
2019, Journal of Membrane Science
Citation Excerpt :
The hybrid process was claimed to be economically more desirable than the conventional design for dehydration of isopropanol [1], and energy-efficient for the separation of alcohol and water [9]. A major obstacle for the design of MAD in industry is the trade-off between the capital cost of membrane and the operation cost of distillation [10]. The optimal process can be obtained by overcoming the trade-off phenomenon.
Membrane-assisted distillation (MAD) is a classic process-integration concept applied for an aqueous azeotrope dehydration. An engineer needs to decide what is the best balance point to trade-off the energy consumption of distillation and the capital cost of membrane module. The current study proposes a design methodology for optimizing the balance point of vapor permeation (VP) membrane-assisted distillation processes. As a generic case, thermodynamically non-ideal process of ethanol dehydration is used to obtain the design information that provides broad insights into the MAD operation. Furthermore, the proposed method provides a reasonable estimation of the concentration and pressure of the connection stream between membrane separation and distillation (which are the most important parameters in the VP-MAD integration process) based on the total annual cost (TAC) calculation in ACM^®. Successful application of the methodology is demonstrated for the dehydration of ethanol with different target product grades (99.6 wt% and 99.95 wt%) that need different hybrid configurations.
A mathematical model for zeolite membrane module performance and its use for techno-economic evaluation of improved energy efficiency hybrid membrane-distillation processes for butane isomer separations
2016, Journal of Membrane Science
Citation Excerpt :
In a series configuration, the feed composition to the membrane unit is fixed, while in a parallel configuration it can be varied depending upon the stage of side stream extraction from the distillation column. However, it has been shown that the side draw stage in a parallel configuration is usually located near the feed stage where the distillation is least effective [148,152-155], which effectively makes it similar to the series configuration. Sometimes, a vapor feed is preferred over a liquid feed for the membrane separation to eliminate the heavy impurities which otherwise may clog the membrane pores.
The aim of this work is to develop enabling tools that can assess the potential of zeolite membranes for industrial applications. The specific objectives are: (1) Develop a detailed mathematical model of a zeolite membrane separation process for accurate performance prediction under industrial conditions, and (2) Perform conceptual process design and techno-economic evaluation of the overall process for an application specific flowsheet. To this end, a detailed mathematical model, based on the real adsorption solution (RAS) theory and the Maxwell-Stefan formulation for transport was developed to describe permeation through a zeolite membrane. Effects like support resistances to transport, use of sweep gas and concentration polarization were included. The model is further applied to study butane isomer separation using a MFI-type zeolite membrane. A comparison of steady state flux and separation factor predicted by the model with the experimentally determined values suggests that the permeation in the real membranes is lower than that for the zeolite crystals. This lower permeance is attributed to the microstructural defects and suggests that there is a considerable scope of improvement in the performance of current state-of-the-art real MFI membranes. It is shown that up to a 10-fold increase in permeance through the membrane is practical, beyond which the external resistance starts to dominate. Furthermore, the detailed zeolite membrane model is integrated into a process level simulation, to evaluate the membrane performance in industrial settings, and a techno-economic analysis is also performed to this end. While single stage membrane process does not achieve the target purity and multi-stage membrane process requires prohibitively large area, a hybrid membrane/distillation process is found to be energy efficient and economically attractive.
Vapor permeation-distillation hybrid processes for cost-effective isopropanol dehydration: Modeling, simulation and optimization
2016, Journal of Membrane Science
Citation Excerpt :
This will ward off the phase changes across the membrane surface, which appears simpler than the pervaporation process. In addition to its simplicity, vapor permeation is less sensitive to concentration polarization on the feed side of the membrane; the membrane lifetime is expected to be longer than pervaporation, due to the low degree of membrane-swelling [14]. Furthermore, the hollow fiber module is used because of its wide applications and large membrane area packed into a small volume [15–17], and it is also capable when combined with a distillation column [18].
This study reports the advantages of a cost-effective unit process using a hybrid distillation and vapor permeation unit for isopropanol dehydration. The feasibility of numerous hybrid membrane distillation schemes for isopropanol dehydration was evaluated by simulation and optimization in Aspen Plus. A built-in model for a membrane separation system was proposed by developing a mathematical model in an Aspen Custom Modeler and integrating it simultaneously with an Aspen Plus. The output results of the rigorous membrane models were consistent with the experimental data from the literature. The influence of the decisive operational parameters, which will be used as an optimization variable to examine the different configurations of hybrid systems, was analyzed. Furthermore, this study also employed the response surface methodology (RSM) to optimize the economical calculation and find the best design for the desired product. The RSM optimization effectively connected the interception of the optimizing variables and its predictions agreed well with the results of rigorous simulations. The most significant savings in the total costs could be achieved by applying a distillation–vapor permeation configuration (approximately 77% compared to azeotropic distillation). Therefore, it is economically beneficial to employ distillation–vapor permeation over the previously proposed hybrid systems of the distillation–pervaporation and distillation–pervaporation–distillation.
Purification of l-(+)-lactic acid from pre-treated fermentation broth using vapor permeation-assisted esterification
2012, Process Biochemistry
Citation Excerpt :
However, a significant increase in total flux was observed for up to 3.06 kg/(m2 h) indicating that this particular system requires less membrane surface area for the same dehydration task. The higher total flux is probably caused by many reasons including the higher operating temperature, and the much lesser hydrodynamic boundary layer effect compared to pervaporation technique [18]. In addition, a further difference between PV and VP is that VP-assisted esterification can be considered as a two steps operation (evaporation form liquid according to VLE followed by a selective dehydration using membrane).
The vapor permeation-assisted esterification of l-(+)-lactic acid and ethanol was investigated using a zeolite membrane. Pervaporation and vapor permeation were initially investigated for dehydration performances, and the latter showed much better results. The molecular sieve property of the membrane resulted in a high separation factor of over 1000 for all conditions. The maximum flux was 10.24 kg/(m² h) at a feed temperature of 145 °C, a water feed concentration of 10 wt%, and a feed pressure of 4.0 bars, respectively. For vapor permeation-assisted esterification using synthetic solutions, the productivity and ethyl lactate yield strongly depended on the dehydration rate. Realistic purifications were performed with fermentation broths of Pediococcus pentosaceus as the lactic acid producer. Experimental results revealed that most of the lactic acid was converted into ethyl lactate at the final stage of the reaction. After distillation and hydrolysis, high purity l-(+)-lactic acid was obtained with more than 95% recovery yields.
Separation of ethyl acetate-isooctane mixtures by pervaporation and pervaporation-based hybrid methods
2012, Chemical Engineering Journal
The separation of binary ethyl acetate–isooctane mixtures by pervaporation and pervaporation-based hybrid methods is studied in this paper. The potential of pervaporation using commercially available membranes (PolyAn GmbH, Germany) was evaluated experimentally and the effect of the feed concentration and the operating temperature on the separation performance was determined. Only two of the eight tested membranes, i.e. POL_AL_M2 and POL_OL_M2 were found preferentially permeable to ethyl acetate and chemically stable up to 25 wt.% of ethyl acetate in isooctane solution, thus restricting the concentration range for which pervaporation can be applied. The POL_OL_M2 membrane combining a maximum separation factor of 22.34 with a total permeate flux of 6.3 kg/m² h at 30 °C and a feed concentration of 25 wt.% ethyl acetate, demonstrated a higher pervaporation separation index (PSI) than the POL_AL_M2 membrane. The obtained retentate was highly concentrated in isooctane (more than 99 wt.%) but the permeate reaches an ethyl acetate concentration lower than 90 wt.%. As maximal isooctane recovery and full ethyl acetate purification could not be achieved by stand-alone pervaporation using the available membranes, pervaporation-based hybrid processes were considered for both solvents. Because of its higher PSI, the POL_OL_M2 membrane was selected for these hybrid processes, aiming at a higher purity of ethyl acetate enriched permeate and total recovery of both ethyl acetate and isooctane.
Integrated Membrane Operations in Various Industrial Sectors
2010, Comprehensive Membrane Science and Engineering
A brief outline on the membrane-based integrated systems precedes the essential part of this chapter. The classification of different hybrid processes is proposed along with the four main groups, that is, membranes with conventional unit processes, membrane contactors, membrane with aggregation processes, and membrane reactors.
Essentially, this chapter comprises an overview of major applications of membrane-based integrated systems in various industry sectors, such as textile, tannery, pulp and paper, metal finishing, and electronic and food industry.
Attention is focused not only on those membrane processes that have become well entrenched in industrial practice in recent years, delivering a long reference list of successful implementations and know-how, but also on some membrane-based integrated processes that are in use only in very specific applications and also at the laboratory level, which are waiting for a broader successful industrial implementation, anticipating a sharp development and generally many breakthroughs in future.

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Design of hybrid distillation and vapor permeation processes

Abstract

J. Membrane Sci.

J. Membrane Sci.

Desalination

J. Membrane Sci.

J. Membrane Sci.