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There are different factors and indices to characterize the performance of a pervaporation membrane, but none of them gives information about their capabilities in the area of liquid separation compared to the most convenient alternative, which is distillation. Membrane flash index (MFLI) can be considered the first and only one that shows if the membrane is more efficient or not than distillation and quantifies this feature too. Therefore, the MFLI helps select the best separation alternative in the case of process design. In this study, the evaluation and capabilities of membrane flash index are comprehensively investigated in the cases of six aqueous mixtures: methyl alcohol–water, ethyl alcohol–water, isobutyl alcohol–water, tetrahydrofuran–water, N-butyl alcohol–water, and isopropanol–water. It must be concluded that the separation capacity of organophilic type membranes is remarkably lower than hydrophilic membranes in all cases of separation. The study of the MFLI is extended with the consideration of other binary interaction parameters like separation factor, permeation flux, selectivity, and pervaporation separation index (PSI) in order to find a descriptive relationship between them. For the same membrane material type, descriptive function can be determined between feed concentration and MFLI and PSI and separation factor, which can be used to calculate each other’s value. On the basis of the indices and especially the MFLI, a significant help can be given to the process design engineer to select the right liquid separation alternative and, in the case of pervaporation, find the most appropriate membrane.

In chemical recipes there can be found guidelines for efficient chemical production typically based on chemistry. However, such guidelines have never been checked with engineering methodologies for...

In the separation industry the extractive heterogeneous-azeotropic distillation (EHAD) is a new and powerful innovation, that is capable of making the separation of highly non-ideal mixtures feasible and economical. In the last years there has been much attention paid to the separation of the minimum boiling homogeneous azeotropes. Although maximum boiling azeotropes are fewer in numbers than the minimum boiling ones but their separation is more complicated but it could be solved with the EHAD, too. Since EHAD is not limited to the separation of minimum boiling azeotropes, the separation of the maximum boiling azeotropes is studied in this work. Our work is motivated by industrial problems because there are such maximum boiling azeotropes in the liquid wastes of the fine chemical industry. The separation of highly non-ideal Water–Acetone–Chloroform–Methanol and Water–Ethyl Acetate–Chloroform–Ethanol quaternary mixtures are investigated and optimized in professional flowsheet simulator environment. Total Annual Costs are also determined. The purity requirement is 99.5 m/m% for Chloroform and the bottom product should be as clear as possible in water so that less liquid organic waste has to be incinerated. It is also an important merit of the EHAD that the chemicals in the distillate can be usually reused supporting sustainability. Different solutions for the separations supplemented with heat integration are examined. On the basis of the computer simulations and the experimental verification it can be concluded, the first time on the literature, that the separation efficiency of EHAD is superior also for the separation of the maximum boiling azeotrope mixtures.

The problem of process wastewater arises not only in fine chemical industry, but also where water is used for washing. In these cases, surfactant material is given to the water, so its washing capability is enhanced. The used water contains surfactant material and dirt. It has high chemical oxygen demand (COD) resulting in serious environmental problems. Finding a solution is inevitable because of the high wastewater fine which has to be paid by the factories if wastewater is emitted without any treatment. A suitable method had to be found that follows the principles of circular economy, so the industrial cycles can be closed like in nature and the water can be reused. Our designed method focuses on different kinds of wastewater containing special surfactant materials, and it has chemical industry relations. The treatment should have reduced the high COD value below to 1000 mgO2/L, which is the discharge limit. It was also aimed that instead of discharging, the treated water could be recycled and reused. Our new physicochemical treatment process consists of a vacuum evaporation method that reduces COD from c.a. 8400 to 1100 mgO2/L. Both laboratory and pilot experiments were investigated. Since this COD value was not satisfactory, a subsequent reverse osmosis membrane operation was also applied. This two-step method, vacuum evaporator followed by reverse osmosis, was able to reduce the COD in wastewater containing surfactant/washing material below the discharge limit. 100 mgO2/L could be reached with using TriSep™ X201 membrane. Penalty calculation and cost estimation also demonstrate the efficiency of our novel method.

The present work was performed because of the paramount importance of terephthalic acid (PTA) in the current chemical industry. It represents the missing element for the production of 100% bio-PET (polyethylene terephthalate) and has a market with continuous growth. The other monomer, monoethylene glycol (MEG), is already widely available from renewable sources. Considering the wide relevance, not only scientific but also social, covered by the possibility of producing one of the most frequently used polymers from renewable sources, this analysis is aimed at the environmental assessment of alternative routes for the production of PTA. In order to do this, the life cycle assessment (LCA) methodology was adopted as a scientific tool which is able to estimate the environmental performance of three pathways from different renewable sources, comparing the results with the traditional technology. An early stage approach was used by comparing different scenarios with two independent methods: CED (cumulative energy demand) and ReCiPe. The results prove that the bio-routes to PTA could be very competitive, in particular, if organic waste streams are converted into raw materials for the production of building blocks. On the other hand, the adoption of dedicated crops has some limitations and it seems not to be the right solution to mitigate climate change by reducing fossil sources.

The fluctuating energy supply at different places of the Earth is a natural phenomenon since the most important energy source on planet Earth is the Sun, that is, solar energy. Humans have been the beneficiary of this natural phenomenon. Making a fire with wood uses stored solar energy. Utilization of biomass, however, is limited by the finite area of arable lands. The housing structures do that job and protect us against external hot or cold temperatures. In the industry, e.g., steel industry, so-called recuperators are applied. The latent heat method is more powerful than the use of sensible heat. Molten material can store heat more efficiently: A large amount of heat can be stored in a small volume. The hydrogen pressure also has an important effect on methane yield. Low pressure of hydrogen is preferred by oxidizing organisms, but high pressure of H2 is needed for methanogens.

This work aims to improve the synthesis of renewable hydrochar (HC) co-fired with coal to reduce grenhouse gas (GHG) emission. Acetic acid catalyzed hydrothermal carbonization (cHTC) of Chlorella vulgaris microalgae biomass was investigated based on a 3(3-1) fractional statistical design of the experiment to examine the effects of hydrothermal reaction temperature (T = 180-220 degrees C), biomass-to-suspension-(BSR = 5-25 wt.%), and catalyst-to-suspension (CSR = 0-10 wt.%) ratios on process performance indicators. Analysis of variance was used to assess the experimental data. The results show that the application of homogeneous catalyst improves the fuel ratio and energy recovery efficiency up to 0.38 and 36.3%. Ex-ante cradle-to-gate life cycle assessment was performed to evaluate the impacts of co-firing ratio (CFR) and hydrochar quality on multi-perspective mid-, and endpoint environmental indicators. The highest decarbonization potential (1.54 kg CO2,eq kWh(-1)) is achieved using catalytic hydrochar biofuel produced at 195 degrees C, 25 wt.% BSR, and 8 wt.% CSR levels. The application of catalytic and autocatalytic hydrochar blends improves the overall environmental impacts and greenhouse gas footprint of solid fuel firing facilitating the transition toward low-carbon emission power generation.

Global warming and climate change urge the deployment of close carbon-neutral technologies via the synthesis of low-carbon emission fuels and materials. An efficient intermediate product of such technologies is the biomethanol produced from biomass. Microalgae based technologies offer scalable solutions for the biofixation of CO2, where the produced biomass can be transformed into value-added fuel gas mixtures by applying thermochemical processes. In this study, the environmental and economic performances of biomethanol production are examined using artificial neural networks (ANNs) for the modelling of catalytic and noncatalytic hydrothermal gasification (HTG). Levenberg-Marquardt and Bayesian Regularisation algorithms are applied to describe the thermocatalytic transformation involving various types of feedstocks (biomass and wastes) in the training process. The relationship between the elemental composition of the feedstock, HTG reaction conditions (380 ?C & ndash;717 ?C, 22.5 MPa & ndash;34.4 MPa, 1 & ndash;30 wt% biomass-to-water ratio, 0.3 min & ndash;60.0 min residence time, up to 5.5 wt% NaOH catalyst load) and fuel gas yield & composition are determined for Chlorella vulgaris strain. The ideal ANN topology is characterised by high training performance (MSE = 5.680E-01) and accuracies (R-2 >= 0.965) using 2 hidden layers with 17-17 neurons. The process flowsheeting of biomass-to-methanol valorisation is performed using ASPEN Plus software involving the ANN-based HTG fuel gas profiles. Cradle-to-gate life cycle assessment (LCA) is carried out to evaluate the climate change potential of biomethanol production alternatives. It is obtained that high greenhouse gas (GHG) emission reduction (-725 kg CO2,eq (t CH3OH)-1) can be achieved by enriching the HTG syngas composition with H2 using variable renewable electricity sources. The utilisation of hydrothermal gasification for the synthesis of biomethanol is found to be a favourable process alternative due to the (i) variable synthesis gas composition, (ii) heat integration, and (iii) GHG emission mitigation possibilities.

It can be stated that in the fine chemical industries, especially in the pharmaceutical industry, large amounts of liquid waste and industrial waste solvents are generated during the production technology. Addressing these is a key issue because their disposal often accounts for the largest proportion of the cost of the entire technology. There is need to develop regeneration processes that are financially beneficial to the plant and, if possible, reuse the liquid waste in the spirit of a circular economy, in a particular technology, or possibly elsewhere. The distillation technique proves to be a good solution in many cases, but in the case of mixtures with high water content and few volatile components, this process is often not cost-effective due to its high steam consumption, and in the case of azeotropic mixtures there are separation constraints. In the present work, the membrane process considered as an alternative, pervaporation is demonstrated through the treatment of low alcohol (methanol and ethanol) aqueous mixtures. Alcohol-containing process wastewaters were investigated in professional process simulator environment with user-added pervaporation modules. Eight different methods were built up in ChemCAD flowsheet simulator: organophilic pervaporation (OPV), hydrophilic pervaporation (HPV), hydrophilic pervaporation with recirculation (R-HPV), dynamic organophilic pervaporation (Dyn-OPV), dynamic hydronophilic pervaporation (Dyn-HPV), hybrid distillation-organophilic pervaporation (D + OPV), hybrid distillation-hydrophilic pervaporation (D + HPV), and finally hybrid distillation-hydrophilic pervaporation with recirculation (R-D + HPV). It can be stated the last solution in line was the most suitable in the terms of composition, however distillation of mixture with high water content has significant heat consumption. Furthermore, the pervaporation supplemented with dynamic tanks is not favourable due to the high recirculation rate in the case of tested mixtures and compositions.

The low efficiency of renewable electricity storage has been considered as a bottleneck of the scalable and low-carbon Power-to-Gas energy transformation concept. This paper investigates the combination of CO 2 biofixation using Spirulina platensis microalgae and catalytic hydrothermal gasification of wet organic feedstock for the storage of fluctuating electricity and direct utilisation of waste CO 2 . The presented method enables wet microalgae biomass conversion into H 2 and C1-C2 rich fuel gas stream using hydrothermal conversion that is valorised further to methane. For bridging the gap between theoretical investigations and the application of this approach, experiments were carried out at elevated temperatures (632.9-717.0 °C) based on a central composite design of the experiment. Biogas upgrading was evaluated by ASPEN Plus flowsheeting software. The results show that the proposed storage cycle outperforms the state-of-the-art biological and chemical-based Sabatier methanations with an overall round-trip efficiency of 42.3%. The optimised thermo-chemical process enables to achieve simultaneously high H 2 (9.05 mol kg−1) and CH 4 (7.91 mol kg−1) yields with an enhanced 71.23% carbon conversion ratio. Moreover, the environmental and cost evaluations of the currently proposed bio-synthetic process indicate low associated CO 2 equivalent emission (99.4 ± 12.6 g CO 2 , e q kWh−1) with 144.9 €MWh-1 normalised total annual natural gas production cost. Ideally the proposed storage cycle requires less H 2 from external sources, effective CO 2 utilisation becomes available through the biofixation and hydrothermal conversion of the wet organic feedstock and closed carbon emission cycle can be accomplished.

The work is motivated by an industrial problem, which is alcohol removal from pharmaceutical process wastewater. The aim of the study was to develop a complete hybrid operation is investigated. Ethanol dehydration, in combination with distillation and hydrophilic pervaporation, is used to investigate about the extent of separation of the ethanol-water mixture. The aim of this research is to rigorously model and optimize this hybrid operation in professional flowsheet simulator environment. The number of minimal theoretical plates of distillation column and minimal effective membrane transfer area are determined. Cost estimation is also examined according to Douglas methodology. Considering our results it can be concluded that, the distillation and hydrophilic pervaporation processes are suitable for separation ethanol and water in 99.5 weight percent purity

Chemical process design is a creative step of engineers that should be supported by different computer-aided design tools. Such tools should be simple and easy to use because process synthesis often means the investigation of a huge number of alternatives. During the design of the separation of liquid mixtures, among many others, distillation and pervaporation are usually simultaneously considered because pervaporation is frequently considered as an alternative to distillation. To easily compare the efficiencies of continuous pervaporation and flash distillation, we propose a new and simple method, the so-called membrane flash index (MFLI). The comparison is based upon vapor–liquid equilibrium data and the permeation data of a pervaporation membrane and therefore can be plotted on a common chart in the case of binary mixtures. The permeation values of organophilic and hydrophilic pervaporations can be calculated with the help of known separation factors and feed concentrations. The MFLI is dimensionless a...

Different research works demonstrate that the pervaporation can replace the distillation or deliver better solutions. It should be, however, accepted with criticism. In our case study, isobutanol-water separation is studied since it is increasingly important in the field of biofuels and process wastewater treatment. There are many options for the separation and they differ in their efficiency, economic features, robustness, development level and environmental impact. Five separation structures are investigated using distillation, both organophilic and hydrophilic pervaporations and hybrid separation units consisting of distillation and pervaporation including heat integrated solutions. The different alternatives are modelled in professional flowsheeting environment. Life cycle assessment, energy evaluation and Multi-Criteria Decision Analysis (MCDA) based on PEST (Political, Economic, Social, and Technological) analysis are completed to evaluate and compare the five alternatives. The feed stream to be separated has the composition of 7 wt% isobutanol 93 wt% water that corresponds to the mixture of the phase split due to the limited solubility. Two product purities are considered, 98.8 and 99.9 wt%. In case of distillation processes, heat integration is also considered, that is, the feed is preheated with its bottom flow. Heat integration significantly improves the efficiency of the distillation and makes it for practically a competitive alternative. The best efficiency can be obtained with heat integrated hybrid separation, that is, the combination of distillation and pervaporation. The pure pervaporation that is the combination of organophilic and hydrophilic pervaporation can be efficient only at sloppy product purities because of the modest separation factor of the organophilic pervaporation membranes. In case of sharp separations, the organophilic pervaporation can be an equally applicable solution as the azeotropic distillation for isobutanol-water separation.

This study continues our research about dividing-wall distillation columns (DWCs) with upper and lower partitions (Ind. Eng. Chem. Res. 2016, 56, 952). Thermodynamic efficiencies and heat demands are investigated to offer a more complex point of view about distillation technologies. Rigorous simulations of nine distillation systems are completed, and the results are evaluated. Among the separation systems there are conventional direct and indirect distillation systems and energy-integrated ones, that is, DWCs with upper and lower partition, columns with side stripper or side rectifier, the fully thermally coupled distillation column, the sloppy system, and a direct sequence with backward heat integration are examined using three different alcohol mixtures. Results are obtained from rigorous simulations using exergy analysis. Thermodynamic efficiencies are in agreement with the expectations based on previous researches. On the basis of the thermodynamic efficiencies and heat demands the direct sequence wit...

Carbon dioxide emission, one of the core cause of global warming and other threats of nonreversible environmental effects, is in focus today. Among the several methods of CO2 emission mitigation, post-combustion carbon capture (PCC), based on absorberdesorber systems with amine absorbents, is one of the promising alternatives. The major anthropogenic CO2 point sources are power plants, natural gas extraction units, oil refineries, cement factories, biogas plants, etc. As these CO2 sources can be treated with a PCC absorber-desorber system, then these two units should cope with various conditions. To maintain a desired high removal efficiency, the capture unit must work in flexible conditions. The aim of this study is to evaluate the influence of the extent of the absorption of carbon dioxide on the overall performance of the acid gas removal process, considering that, generally, as the amount of removed CO2 increases, the separation becomes more challenging. In this work a verified computer based process model for the absorber-desorber system is used. Aspen Plus® professional flowsheet simulator is used for this purpose. Attention is paid on the proper operating parameters of a PCC absorber-desorber system for the case of increasing the CO2 capture efficiency up to 99%. As alternative solutions for these cases different scenarios are considered: • the increase of the capacity of a classic configuration of an absorber-desorber system; • the introduction of a second absorber column as extending the absorption column height; • the possible use of two absorbers and two desorbers working in series. This work deals with the detailed study on maximizing CO2 removal efficiency while maintaining the minimal energy consumption for the absorbent regeneration section.

CO2 is the primary greenhouse gas (GHG) due to its large quantity of anthropogenic emission. In this work the amine based carbon capture process and the CO2 storage, called Carbon Capture and Storage (CCS) is analysed from different viewpoints. PESTLE (Political, Economic, Social, Technological, Legal and Environmental) analysis of the CCS alternatives (Fossil based, Improved process, Renewable based) is investigated in detail and the alternatives are also compared with the uncontrolled CO2 release using Life Cycle Assessment (LCA) methods. Life cycle inventory data is set up and analysed with four life cycle impact assessment methods. In order to conclude the comparison of CCS and the uncontrolled release of CO2 a Multi-Criteria Decision Analysis (MCDA) is also applied with Multi Attribute Value Theory (MAVT) method. Our results show that applying process improvement and renewable energy sources (e.g., biogas) for absorbent regeneration result in a CCS technology of much smaller environmental and social impacts, and therefore the CCS technology becomes more favorable than the uncontrolled release.

This study deals with the prediction of distillation trays’ efficiency in rectification columns, in case of low carbon content hydrocarbons (for example ethane-ethylene and propane-propylene) separation. During these technologies typically trayed columns are used, therefore the bubble cap and sieve trays were investigated in this paper. In the previous studies, we have assumed that the leaving vapour and liquid from each tray is in equilibrium. It assumed that the trays have 100% efficiency, however, in practice, this supposition is not true. It means that it is necessary to determine the actual efficiency of the trays because this value gives the actual trays’ number too. The studied methods are the O’Connell method and the AIChE method (Perry 1950). This study’s goal is to calculate and compare different trays’ efficiency because it has an effect of the tower height. In petrochemical industry the previously mentioned hydrocarbons have a high importance, these are the raw material of the plastic manufacturing. Generally, hydrocarbons are produced by distillation from higher carbon content materials, and this procedure has extremely high energy consumption. In case of higher plate efficiencies, the costs can be reduced.

The distillation based separation can be extremely complex if highly non-ideal mixtures are to be separated. In spite of different successfully applied unit operations there is always a possible way to improve the distillation technique and widen its toolbar. A novel improvement in this area is the development of the extractive heterogeneous-azeotropic distillation (EHAD). For the sake of the demonstration of the efficient use of EHAD in Dividing wall columns (DWC), two quaternary mixtures are selected for separation: Water – Ethanol – Ethyl acetate – Acetone and Water – Ethanol – Ethyl acetate – Ethylene glycol. There are real waste mixtures from pharmaceutical industry. It must be mentioned, extractive heterogeneous-azeotropic distillation method has never been investigated in dividing wall columns. Conventional distillation column sequences and dividing wall columns are selected for comparison. Rigorous steady-state simulations are carried out using ChemCAD flowsheet simulation software. Number of trays, heat duties and Total Annual Cost (TAC) of the systems are optimized. It can be concluded, the application of the EHAD in DWCs allows also the simplification of the separation schemes and the separation reduces the energy requirements of the distillation and opens new horizons for the separation of non-ideal mixtures saving energy, money and natural resources. Using DWCs the reboiler duties can be reduced with 20% and the appropriate separation can be reached with one less column.

The application of vapour-liquid equilibria-based separation alternatives can be extraordinarily complicated for the treatment of process wastewaters containing heterogeneous-azeotropic. Despite dissimilar successfully tested methods for separation, there is possibility to get better distillation method by enabling the separation of more and more specific process wastewater. Extractive heterogeneous-azeotropic distillation (EHAD) is a new advance in treatment of fine chemical wastewater showing special features to cope with the treatment of highly non-ideal mixtures. This method combines the worth of heterogeneous-azeotropic and extractive distillations in one apparatus without addition of any extra materials. The study of the separations of ternary component process wastewater from the fine chemical industry shows both in the modelled and experimental results that EHAD can be successfully applied. The measured and modelled compositions at extreme purities, that is, close to 0% or 100%, can be different because of the inaccuracies of the modelling. This highlights the paramount importance of the experiments if special extra-fine chemicals with almost no impurities, e.g. of pharmacopoeial quality are to be produced by special distillation technique. This study expands the application of EHAD technique, this new field is the separation of process wastewaters.

The annual amount of waste tires is enormous and permanently on the increase. Since their structure resists both physical and chemical degradation, their appropriate processing is an environmentally important subject and it is still a current research topic despite of the already existing technologies e.g. pyrolysis, thermal utilization. In our work, a novel selective physical separation technology of waste tires is developed, presented and investigated. The technology is based on our new disassembling machine that enables the selective separation of the tread material of any kind of tires apart from their other constituting materials. The separation is an automated cutting process and its thermal profile is examined with a thermal imaging camera to determine if the cutting process can be associated with any kind of thermal degradation of the tread material. It is also an aim to detect if a special construction material of high thermal resistance would be needed for the cutting device. The experimental results are analyzed with the help of special software and it is found that the temperature values of the tire and the disassembling device can be classified into four different thermal zones. It is also determined that our novel device can be applied for tire machining; no thermal degradation occurs during the process, and there is no need for special construction material for the novel cutting device.

Microalgae-based biorefineries for the production of renewable biofuels like biodiesel, upgraded bio-oil, biochar, biogas and other high-value chemicals have received great attention in recent decades as potential major sources of energy for the future. Microalgae are a suitable species to produce biodiesel and other high energy density by-products; however, it is questionable whether a net energy gain can be realized or not considering the whole processing chain. In the present study, the energy balances of different algae-based biofuel and bioenergy production technologies are investigated in detail and compared to each other corresponding to a cradle-to-grave overall energetic analysis. The study includes cultivation, harvesting, cell pretreatments (cell disruption, drying, grinding), lipid extraction, transesterification, gasification and hydrothermal liquefaction with bio-oil stabilization and hydroprocessing. The energy consumption and energy gain are estimated for each operational step to determine the net energy ratio (NER, energy output over energy input) for the overall technologies studied. Our detailed investigation enables to detect the most energy consuming unit operation, that is, the bottleneck point(s) of the microalgae-based technologies which should be still improved in the future for the sake of more efficient algae-based biorefineries. The investigation makes also possible to evaluate and compare the different large scale alternatives for biomass transformation. Positive energy balances with a NER value of 1.109 and 1.137 are found in two already existing processes: open raceway ponds and closed photobioreactors, respectively. Our work gives also a detailed algorithm that can be followed at the evaluation of other microalgae-based biorefineries.

Computer aided process design is improving with newer and newer tools. One of such tools is the automatic calculation technique that enables the combination of different software tools to enhance the efficiency of the calculations. In our research work Aspen HYSYS model of a petrochemical plant is built in order to simulate responses of an existing plant to the changes in the composition and amount of feed material. The Aspen HYSYS is connected to Microsoft Excel program; simulated operational data are stored in an operational database and transported to Excel for further analysis. The automatic calculation completed with the two software tools mutually strengthens their merits and results in enhanced insight into the operational features of any plant. Comparison of the projected input parameters of the petrochemical plant studied shows that the extension of the plant is badly needed. Cash-flow analysis suggests that the extension is profitable.

The distillation based separation can be extremely complex if highly non-ideal mixtures are to be separated. In spite of different successfully applied unit operations there is still a possible way to improve the distillation technique and widen its toolbar. A new improvement in this area is the development of the extractive heterogeneous-azeotropic distillation (EHAD). This unit operation includes the merits of extractive- and heterogeneous-azeotropic distillations in one unit without extra material addition. Our work supports EHAD features with successful experiments compared with modelling and comparison with other separation structures proving that the application of EHAD makes the separation of extremely non-ideal mixtures possible on an easy, powerful, energy saving, and cost efficient way.

The energy and raw material supplies are crucial issues in our societies. The possible solution of these issues can be coupled with the storage alternatives of renewable energy. The chemical way of energy storage can be quite different but we follow the Supplement of Natural Gas concept since this delivers a high storage capacity solution. The chemical way of energy storage is based on the carbon dioxide hydrogenation. It is in agreement with the theory of the circular economy so that the carbon emission is reduced with the concept of Carbon Capture and Utilization (CCU). In this work the reaction system of the carbon dioxide hydrogenation is studied thermodynamically applying the tool of quantum chemistry. The aim of the study is to support the carbon dioxide transformation alternatives of industrial scale, that is, the CCU. It is determined that the methane production has the highest thermodynamic efficiency where the methanol production is the second in the ranking. These thermodynamic efficiencies are 14.4% for methanol and 44.4% for methane. Both alternatives have, however, advantages since the methane can be introduced directly into the natural gas network and the methanol has the highest volumetric energy content. Both molecules can be transformed into different kind of raw materials, see e.g. methanol economy. At the selection, however, other, practical points of view should be also considered where industrial experiences and circumstances are to be also taken into account. Having recognized the need to deal with the reduction and utilization of carbon dioxide emission (CCU), the University of Miskolc established the “Environmental Carbon Dioxide Partnership”. It has several industrial partners having significant carbon dioxide emission and therefore experience in this issue. The experts of the partnership help to solve emission problems and the carbon dioxide utilization, based on the theoretical and practical results and experiences of the Partnership. This thermodynamic investigation supports the development of the Partnership to carry out the most efficient CCU method.

Processes applied for the capturing of carbon-dioxide from industrial gases are in the focus of the reduction of green-house gas emission. The highest amount of anthropogenic CO2 is emitted in flue gas form but with varying gas composition according to the source and the circumstance of the combustion of fossil fuel. A typical method for such CO2 capturing is an absorber–desorber system where the absorbent is quite frequently 30 wt% aqueous monoethanolamine (MEA) solution. The aim of our work is to setup an adequate and verified computer based process model that is capable for the rigorous simulation and analysis of the treatment of various flue gases, evaluating the purification of different types of flue gases to see the environmental aspect and further possible process improvements. For the verification of the absorber–desorber model, measured data are applied. The data are obtained on an existing absorber–desorber system of pilot plant size for the cases of two different test gases of different compositions. It is shown and explained why the equilibrium stage model is not accurate in such cases but the non-equilibrium stage assumption, that is, the rate based modeling is suitable. Modeling explains the reasons of why the operation with less absorbent need higher energy for the operation than the optimal one and shows the effect of carbon footprint of the energy demand achieved with various fuels used for desorber heating.

This work investigates the techniques used in evaluating distillation structures from lean manufacturing point of view. Oil & gas industry has already started adopting lean manufacturing principles in different types of processes from information flow to processing technologies. Generally, energy costs are the most important factors in processing hydrocarbons. Introducing flexibility desired by lean principles to the system may conflict energy efficiency of the system. However, this does not mean that the economic optimum is the energetic optimum. Therefore all possible changes due to temporarily stopped or not fully utilised plants have to be investigated, resulting in a large amount of cases that have to be evaluated. For evaluation exergy analysis can be used as it involves all energy types, and evaluation is straightforward. In this paper plain distillation structures are investigated, and the boundaries of the systems are set up according to the status of the site. Four component case studies are presented that show that the very same distillation structure can be more or less efficient depending on the status of the industrial site. It is also shown that exergy analysis used with different boundaries on the same system can show flexibility of the system and reveals potentials.

Distillation is an important and widely applied separation method. One of its major application areas is crude oil refining. We investigate and compare two different refinery technologies: (i) conventional, atmospheric and vacuum, AV-plant, and (ii) an alternative one, the so-called progressive distillation technology. For the sake of the comparison, simulation models of the two different distillation technologies are built in professional flowsheeting software environment. The investigation includes the study of crude oil fractionation on the examples of processing different types of crude oils. Both technologies are also evaluated with the tools of pinch technology. On the basis of the results of the pinch analysis, heat exchanger networks are also designed. The operating and capital costs are estimated for the energy integrated cases designed on the results of pinch technology. A comparison of the results shows that the progressive distillation plant proves to be both more energy efficient and economic...

A complex treatment of process wastewaters (PWW) of the pharmaceutical industry has been elaborated, the objective was their common disposal and utilization. The biodegradability of polluting components is concentration dependent, the mixing of PWWs with domestic wastewater at WWTP is possible, if no toxic and/or non-biodegradable components are present. So the organic content can serve as carbon source in the denitrification step. The characterization and the proper treatment methods of PWWs have been developed. Only 20-30 % of PWWs required pretreatment. The majority can be mixed directly with the domestic wastewater and send to the WWTP. The characterization includes COD, TOC, BOD, AOX, volatile content, toxicity, metal ion content measurements. The pretreatment methods could be: distillation, WO or catalytic WO. After the activated sludge treatment the degradation of emergent pollutants and the disinfection can be performed by UV-Fenton or high energy irradiation. The design of a complex treatment plant attached to a WWTP of 100000 m3/day capacity and its life-cycle analysis to determine the environmental benefits were carried out also.

The distillation based separation can be extremely complex if highly non-ideal mixtures are to be separated. In spite of different successfully applied unit operations there is still possibility to improve distillation technique and widen its toolbar. A new improvement in this area is the introduction of the extractive heterogeneous-azeotropic distillation (EHAD). This unit operation includes the merits of the extractive and heterogeneous-azeotropic distillations in one unit without an extra material addition. In spite of the complexity of this unit operation it can be efficiently applied and complex separation technologies can be simplified with its application. The separations of ternary and quaternary mixtures from the fine chemical industry show both in the modelled and the experimental results that the extractive heterogeneous-azeotropic distillation is an efficient tool of this area. Demonstrating the accuracy of EHAD, the separation of methanol–ethyl-acetate–water and ethanol–ethyl-acetate–water mixtures are examined and the EHAD is compared with conventional distillation techniques. These separation processes are rigorously modelled and optimized with dynamic optimization method in professional flowsheeting environment. The objective function is the total annual cost but the energy consumption is also investigated. The modelling results are verified with laboratory experiments, too. It can be concluded that the extractive heterogeneous-distillation is a capable method for the separation of these highly non-ideal mixtures.

Carbon dioxide is a powerful greenhouse gas, whose massive presence in the atmosphere causes gradual global warming. Absorption by means of chemical solvents is the most commonly used process for CO2 removal. It can be applied to gaseous streams in power plants, natural gas, and refinery gas. Amine scrubbing is widely considered the most mature technology for PCC (post-combustion CO2 capture), and 30% wt. MEA aqueous solution can be taken as the baseline solvent to be used as reference for studies focused on modelling and simulation. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. The thermodynamic model exerts an influence also on the determination of the overall heat of absorption of the acid gas in the solvent, being the heat released at chemical equilibrium related to the extent of reactions. Its estimation is of paramount importance, since it is directly related to the energy requirement at the reboiler of the solvent regeneration column and determines the temperature profile along the absorber. The model used in this work has been previously validated by comparison with data of absorption performances with regard to mass transfer phenomenon. In this work, results obtained from simulations have been checked against experimental data, by focusing on the thermodynamic framework and its influence on the evaluation of the reboiler duty, for possible energy saving solutions in scale-up design.

Pervaporation is proved to be a commercially viable membrane separation process by this time. However, to become a widely applied process in the industry it is of crucial importance to develop membrane properties, process and module design as well as proper modelling in professional software environment. In this work a pervaporation model improvement of the basic solution–diffusion model ( Rautenbach et al., 1990 ) is recommended and tested on experimental data. The reason behind this improvement is that the transport coefficient cannot be considered as constant assumed in the basic model in a wide concentration range. The change of the transport coefficient is considered as an exponential function of the composition of permeating compound. This exponential dependency is assumed by the authors after investigating the shape of the flux curves measured in a wider feed concentration range. The accuracy of this improved model is experimentally tested with the pervaporation of isobutanol–water, n-butanol–water, and ethanol–water mixtures on commercial hydrophilic composite membranes. This model improvement gives accurate and reliable data for a wide range of feed concentration proving that the assumption of practically constant transport coefficient cannot be applied. Therefore the use of this improved model in professional flowsheeting software packages is more reliable and reasonable than the application of the basic model for the design and operation of pervaporation, or a more effective hybrid separation system including pervaporation.

Carbon dioxide capturing processes from industrial gases are widely applied to enrich valuable gas and to reduce green-house gas emission. The highest amount of anthropogenic CO2 is emitted in flue gas form. Flue gas composition varies in a wide scale therefore designing such plants that are able to operate on a good removal efficiency scale is vital. A typical method for such gas separation is an absorber-desorber system where the absorbent is 30 w% aqueous monoethanolamine solution. The aim of this work is to setup computer based process model that is capable of simulating CO2 capture from flue gases and to study its performance at different operating conditions. We investigate possible process improvements by enhancing the CO2 removal efficiency with the variation of different key parameters and different plant setups. We also take into account the regeneration energy demand by optimizing the system to the lowest specific energy demand. Results show that the least attractive option is the overload of the existing absorber-desorber system. By introducing a second absorber-desorber step, high removal efficiency can be reached while maintaining low desorber temperature. The best performance can be achieved with increasing the absorber height and elevated desorber pressure that can reduce the specific regeneration energy especially at high removal efficiency region. This result is in agreement with the argued classical absorber design and operation philosophy that the absorber should be operated at extremely low loads, which is in association with overdesigned absorber column packing heights. This offers the possibility for flexible operation.

In the case of process design a new graphical representation method is proposed on the basis of computer modelling of distillation and pervaporation. The new method relies on also vapour-liquid equilibrium data. The comparison can be performed on a common y-x equilibrium diagram of the mixture to be separated. In our work methanol-water, ethanol-water and isobutanol-water are the investigated systems. The alcohol permeate composition values are plotted over the feed composition. Permeate alcohol concentrations are calculated with the help of known separation factors and feed alcohol concentrations. The corresponding vapour-liquid equilibrium composition is also shown so that pervaporation and flash distillation could be compared. In the case of methanol and ethanol separation a lower separation capability of the different PDMS membrane is detected than a flash distillation. In the case of isobutanol-water mixture every calculated isobutanol permeate weight fractions of different organophilic membranes are above the equilibrium vapour concentration. The proposed graphical representation method visualizes the feasible operation ranges of distillation and pervaporation. It enables also the designing engineer for the proper selection of the separation method.

The increasing price of energy, the security of supply, the reduction of green house gases, and the scarcity of oil and gas urge the use of more and more renewable energy. An important renewable energy source is the biomass which can be applied for heat, electricity, and transportation fuel production. The heat and electricity production are the so called “direct utilisation” alternatives and the transportation fuel production alternatives are the “indirect utilisation” alternatives of biomass energy. If efficient land use is considered, the alternatives can be compared on the basis of the utilisable energy produced from the biomass per hectare. It is shown that the bioethanol production from corn has about 89–99% less energy production capability than that of the direct utilisation alternatives. The cellulosic type bioethanol production technologies, since these partially directly utilise the biomass energy, have better energy utilisation potential, that is about 40–50% of direct alternatives.

This work presents a process design methodology that evaluates the distillation systems based on exergetic, economic, and greenhouse gas (GHG) emission aspects. The aim of the methodology is to determine how these three features should be applied in process design to obtain information about the accuracy of the design alternatives. The methodology is tested and demonstrated on three different energy-integrated distillation systems: the direct sequence with backward heat-integration (DQB), fully thermally coupled distillation column (FTCDC), and sloppy distillation system with forward heat-integration (SQF). The average relative emission saving is the highest for the DQB scheme and this sequence shows the most flexible range of use. The case studies prove the accuracy of our evaluation methodology. On the other hand, it highlights and demonstrates that the exergy analysis can predict the results of the economic study and the environmental evaluation to make the decisions, associated with process design, much simpler. © 2009 American Institute of Chemical Engineers AIChE J, 2010

Impact assessment can be completed with the help of Life Cycle Impact Assessment (LCIA) as a part of Life Cycle Assessment (LCA) and External Cost Assessment methods. These methods help, for project and product classifications, to protect human health and the environment. Comparison of different impact assessment methods along parallel evaluations of real air pollution case studies helps to detect similarities and dependencies between them. The comparison helps and supports the work in both areas by mutually exploiting the merits of both methods. On the other hand, the detected similarities and dependencies also support the accuracy of the assessment work. Two impact assessment methods are compared to detect the dependencies between them. These are: the damage-oriented Life Cycle Impact Assessment method Eco-indicator 99 (EI99) and the Cost-Benefit Analysis (CAFE CBA) carried out within the framework of the Clean Air for Europe Programme of the European Union. Arithmetic comparison of the two methods’ impact indicators is carried out in order to show how differently they assess and evaluate the environmental impacts of the same pollutants. Moreover, air pollution inventories of five industrialized cities in Poland are evaluated in parallel with the two impact assessment methods. The uncertainties of the two methods are also considered and Monte Carlo simulations are completed to obtain probability intervals of impact indicators and overall mean values of the generated populations. The arithmetic comparison of the impact indicators shows a strict correlation between the two impact assessment methods. This correlation is confirmed by results of the parallel evaluation of the real case studies. The comparison of the overall mean values obtained by the Monte Carlo simulations also shows a clear dependency between the results of the two impact assessment methods. After detecting the dependencies between the two methods, the best guess values of the EI99 indicator are selected and applied to make a ranking of the air pollutants and their emission sources for an industrialized Polish city. It can be concluded that the detected correlation between the two methods (EI99 and CAFE CBA) supports and helps the accuracy of the impact assessment. If the uncertainties of the methods are also considered, it is proved for the examples of real case studies that they correlate in their results. On the other hand, the best guess of the EI99 indicators can be used to rank emissions according to their relative damage to human health and the ecosystem, and to locate emission sources. These results help decision-makers to conclude an efficient environmental conscious policy.

A simulation tool is developed in order to support the operation of an industrial scale hybrid distillation–pervaporation system that is used to regenerate isopropanol. Laboratory-scale experiments were carried out to determine the parameters of a semi-empirical solution–diffusion membrane transport model that is used for the modelling of the pervaporation transport. Isotherm experiments were made at three different temperatures (60, 80, 90°C) using a hydrophilic flat sheet membrane (PERVAP 2210, Sulzer Chemtech). The permeate fluxes and compositions were measured at different constant feed compositions. The parameters of the applied transport model were fitted to the experimental data. For simulating the pervaporation apparatus, an earlier developed user added pervaporation module within the ChemCad software package was applied. The user added module and the fitted transport model parameters were used for the simulation of our measured laboratory-scale data. Simulation of the industrial scale distillation pervaporation hybrid system was also carried out. The simulated and measured data were compared.

Hybrid separation processes are becoming more and more important in the practice if membrane technologies are also involved. In this work, a systematic investigation is completed for three sequence alternatives of distillation and pervaporation. These are the following: pervaporation followed with distillation (PV+D), distillation followed with pervaporation (D+PV), two distillation columns and a pervaporation unit between them (D+PV+D). The hybrid separation process alternatives are evaluated with rigorous modelling tools, but first, a rigorous simulation algorithm is determined for the pervaporation. The three hybrid separation processes are rigorously modelled with CHEMCAD, and optimized with the dynamic programming optimization method for the case of the separation of ethanol-water mixture. The objective function is the total annual cost (TAC). The energy consumption is also investigated. The selection of the ethanol-water mixture has two motivations: (i) it is quite often studied and well known, and (ii) to make biofuel (ethanol) production more economical, membrane technologies might also be applied. The results are compared with each other and with the classical separation completed with heteroazeotropic distillation. The optimized TAC shows that the distillation column followed with pervaporation is the most economical hybrid separation process alternative. Its TAC is about 66% of that of the classical separation.

The rigorous modelling of pervaporation, especially in professional software environment, plays a high practical importance if hybrid separation processes containing membrane units are to be designed. In this work a methodology is recommended and presented for such design problems. This methodology consists of the following steps: laboratory pervaporation experiments, estimation of the parameters needed for the modelling of the pervaporation, and finally the double verification of the parameters. The parameter estimation is handled as a mixed integer nonlinear programming (MINLP) problem and professional flowsheeting simulator is also applied in the double verification step. Following this methodology, reliable parameters of the pervaporation needed for rigorous modelling can be determined. The pervaporation module with the reliable parameters in professional software environment enables the design of complicated separation processes, e.g., hybrid separation processes containing pervaporation.

Design of novel hybrid processes is performed for the industrial recovery of tetrahydrofuran (THF) from two different highly non-ideal mixtures. The novel hybrid processes combine the advantages of batch and/or continuous distillations, extractive distillation, and pervaporation for efficient separation of highly non-ideal mixtures. Pervaporation, used for the final dewatering of the THF, is the last step in the separation technologies and carried out with available industrial technology (Sulzer Chemtech GmbH, Batch pervaporation BP models, PERVAP ® 2210 membrane type). It is necessary, however, to design a proper pre-separation process of the mixture to be pervaporated and coordinate its operation with the pervaporation unit. Since methanol is also present in one of the mixtures, its behaviour during pervaporation is also investigated. It shows that since the methanol is able to permeate the membrane, it should be separated in the pre-separation process. The vapour–liquid equilibrium data indicate that with extractive distillation it becomes possible to break the THF—methanol azeotrope and the appropriate application of pervaporation makes the further reduction of the recovery costs possible. The total annual costs of the novel hybrid separation processes range between 10.3 and 54% of that of the old technology based on chemical dewatering. The THF loss decreases to the 7.5 and 17% of that of the old technology and shows that pervaporation is also a powerful tool for the application of the principles of the sustainable development and consumption.

Energy consumption of distillation needs high portion of the total energy demand of the fuel- grade bioethanol production. Pervaporation, being a membrane separation process, is a promising alternative process to distillation. A detailed analysis was performed considering the energy demand of concentration of ethanol solution obtained during fermentation up to the fuel-grade quality applying both hydrophilic and hydrophobic membranes. It was also discussed how the specific energy demand of the process varies during the pervaporation process and how energy consumption can be reduced applying pervaporation process with different operating modes. It was stated that standalone pervaporation process can provide fuel-grade quality biofuel at very high separation coefficient, only, using consecutively switched hydrophobic and hydrophilic membranes. Three- stage pervaporation process is needed at separation coefficient of 50, and two-stage one at separation coefficient of 100 to achieve the desired quality. Application of a hybrid process with lower membrane separation coefficient can give the desired quality by lower energy than that the distillation alone. Thus, the hybrid process can provide saving of essential amount of energy comparing it with the energy demand of distillation. However, the commercially available membrane, at present, has not the desired selectivity for replacing, at least partly, the distillation.

The distillation-based separation of ideal liquid mixtures has been comprehensively studied. The optimization of the different separation structures has allowed the development of general heuristic rules to aid the designers in finding good solutions quickly for the type of problem at hand. The separation of nonideal mixtures is also an exhaustively studied area, but because of the complexity of the vapor-liquid-liquid behavior of such mixtures, it is more difficult to suggest guidelines for synthesis in separation sequences. On the other hand, recently several special so-called hybrid separation tools have also been involved in that kind of synthesis task, complicating further the synthesis problem. To obtain some general conclusions for the separation structure synthesis of such mixtures, in this study the separation of two nonideal quaternary mixtures containing one nonazeotropic-forming component (most volatile or least volatile) is studied based on optimization of the separation structures. The separation schemes involve the so-called extractive heterogeneous azeotropic distillation, which is a novel hybrid separation process. The economic optimization of the different separation structures results in the conclusion that the heuristic rule for ideal mixtures, that is, easy separation first should be done and the complicated one should be made last, is valid also for such nonideal mixtures.

In this contribution, the advantages of the artificial neural network approach to the identification and control of a laboratory-scale biochemical reactor are demonstrated. It is very important to be able to maintain the levels of two process variables, pH and dissolved oxygen (DO) concentration, over the course of fermentation in biosystems control. A PC-supported, fully automated, multi-task control system has been designed and built by the authors. Forward and inverse neural process models are used to identify and control both the pH and the DO concentration in a fermenter containing a Saccharomyces cerevisiae based-culture. The models are trained off-line, using a modified back-propagation algorithm based on conjugate gradients. The inverse neural controller is augmented by a new adaptive term that results in a system with robust performance. Experimental results have confirmed that the regulatory and tracking performances of the control system proposed are good.

The solvent recovery is often the separation of highly non-ideal mixtures. The separation and recovery of quaternary solvent mixtures coming from printing and medicine factories are investigated. The components of the six quaternary mixtures studied in form of heterogeneous and homogeneous azeotropes of minimum boiling point. The mixtures can be categorised into three groups according to their VLLE behaviours. After studying their behaviours, three novel hybrid separation processes based on the extractive heterogeneous-azeotropic distillation, a special kind of new distillation, are developed and recommended for each group of solvents. In the novel processes, beside the extractive heterogeneous-azeotropic distillation, ordinary distillations and phase separation units are also used utilising the fact that the combination of such units, the hybrid processes, offer a higher variety of the possibilities for the separation of highly non-ideal mixtures. The separation processes are verified experimentally and the agreements between the simulated and measured data prove to be rather favourable. A strategy is recommended for the use of the novel hybrid processes developed according to the VLLE behaviour of the non-ideal quaternary mixtures.

Four different alternatives of mobile power train developments (hybrid diesel, fuel cell operating with hydrogen produced on a petrochemical basis, methanol reformer-fuel cell system, gasoline reformer-fuel cell system), are compared with the gasoline internal combustion engine (ICE), for well-to-wheel efficiencies, CO 2 emissions, and investment costs. Although the ICE requires the lowest investment cost, it is not competitive in well-to-wheel efficiencies and less favourable than the above alternatives for CO 2 emissions. The hybrid diesel power train has the highest well-to-wheel efficiency (30%), but its well-to-wheel carbon dioxide emission is similar to that of the fuel cell power train operated with compressed hydrogen produced on a centralised petrochemical basis. This latter case, however, has the advantage over the hybrid diesel power train that the carbon dioxide emission is concentrated and easier to control than the several point-like sources of emissions. Among the five cases studied only the on-board reforming of methanol offers the possibility of using a renewable energy source (biomass).

Direct separation sequence without, with forward, and with backward energy integration, indirect separation sequence without, with forward, and with backward energy integration, sloppy separation sequence without (preflash system), with forward, with backward, and with double energy integration, and thermally coupled sloppy separation sequence (Petlyuk system) are compared with short-cut and rigorous modelling. Based on theoretical considerations and economically evaluated rigorous case studies for ternary mixtures it is demonstrated that in the most cases the Petlyuk system is not superior to the energy integrated configurations even in energy savings. According to the energy consumption of sharp separation determined by short-cut methodology, all the sloppy sequence structures are equivalent. According to the energy losses determined by short-cut methodology, derived here, the energy-integrated structures win almost everywhere in the studied conditions that include a range of relative volatility ratios and the whole feed composition triangle. According to rigorously simulated and optimised results, together with controllability studies, the advantageous application of the thermally coupled (Petlyuk) systems is constrained to a very small range of relative volatility ratio, feed composition, and price structure. This small range is situated somewhere around balanced relative volatility ratio A/B to B/C, small amount of the middle component B, balanced presence of the two swing components A and C in the feed, and high energy costs to investment costs ratio or slow depreciation rate.

Two energy integrated distillation schemes for the separation of three different ternary mixtures of four typical feed compositions have been rigorously investigated and compared to the best conventional two-column distillation scheme. The two energy integrated schemes are: the heat integrated two column system and the fully thermally coupled distillation column (FTCDC), also known as Petlyuk column. The comparison of the energy savings and the total costs of the investigated schemes show that the heat integrated two column scheme is economically always better than the conventional scheme. The FTCDC shows considerable energy savings in several cases, however, it can be competitive with the heat integrated two column system only in those rare cases where the concentration of the middle component is high, the split between the first and second components is harder than the split between the second and third components, and the separation is not too sharp (Annakou and Mizsey, 1996). The rigorous economic study is supported by controllability studies for the two energy integrated distillation schemes. Degrees of freedom analysis and steady-state multivariable control structure synthesis tools show that both investigated schemes can be controlled by conventional decentralised control structures, however, in the case of the heat integrated two column scheme heuristics and also the steady-state control indices show that the interaction among the control loops is less than in the case of the FTCDC. The dynamic simulations of the two energy integrated schemes without and with the most promising control structures support the steady-state analysis. They also demonstrate that in the case of the control of the FTCDC due to the significant interaction among the control loops detuning of the controllers is necessary. Higher overshoots, longer settling time and more sluggish behaviour are expected compared to the heat integrated two column system.

The carbon dioxide capture is a more and more important issue in the design and operation of boilers and/or power stations because of increasing environmental considerations. Such processes, absorber desorber should be able to cope with flue gases from the use of different fossil primary energy sources, in order to guarantee a flexible, stable, and secure energy supply operation. The changing flue gases have significant influence on the optimal operation of the capture process, that is, where the required heating of the desorber is the minimal. Therefore special considerations are devoted to the proper design and control of such boiler and/or power stations equipped with CO2 capture process.

This paper presents results of a rigorous study and comparison of conventional and energy-integrated distillation schemes for the separation of ternary mixtures. The major part of this work is devoted to the design and simulation of the fully thermally coupled distillation column (Petlyuk or Kaibel column) with particular emphasis on the question of the fractional recovery of the middle component in the prefractionator and as a consequence the internal recycle streams. A comparative economic parametric study is carried out for three different distillation schemes: conventional sequences, heat-integrated columns, and the fully thermally coupled distillation column. The heat-integrated columns show the best economic features over the other two schemes except the few cases when the concentration of the middle component in the feed is high and the A/B split is more difficult than the B/C split. In such rare cases the fully thermally coupled distillation column proves to be the cheapest solution. In the cases...