Energy Conversion and Management 77 (2014) 287–297

Contents lists available at ScienceDirect

Energy Conversion and Management

journal homepage: www.elsevier .com/ locate /enconman

Advances in heat pump assisted distillation column: A review

0196-8904/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.enconman.2013.09.055

⇑ Tel.: +91 3222 283918; fax: +91 3222 282250.E-mail address: akjana@che.iitkgp.ernet.in

Amiya K. Jana ⇑Energy and Process Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721 302, India

a r t i c l e i n f o a b s t r a c t

Article history:Received 22 April 2013Accepted 28 September 2013

Keywords:Heat pumpingDistillationVapor recompressionHybrid heat pump systemsBatch processing

Progressive depletion of conventional fossil fuels with increasing energy demand and federal laws onenvironmental emissions have stimulated intensive research in improving energy efficiency of the exist-ing fractionation units. In this light, the heat pump assisted distillation (HPAD) scheme has emerged as anattractive separation technology with great potential for energy saving. This paper aims at providing astate-of-the-art assessment of the research work carried out so far on heat pumping systems and iden-tifies future challenges in this respect. At first, the HPAD technology is introduced with its past progressesthat have centered upon column configuration, modeling, design and optimization, economic feasibilityand experimental verification for steady state operation. Then the focus is turned to review the progressof a few emerging heat integration approaches that leads to motivate the researchers for further advance-ment of the HPAD scheme. Presenting the recently developed hybrid HPAD based heat integrated distil-lation configurations, the feasibility of heat pumping in batch processing is discussed. Finally the workhighlights the opportunities and future challenges of the potential methodology.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

There is a steep rise in global energy consumption mainly be-cause of the increasing industrialization and motorization of theworld. Fossil fuels meet 80 percent of our primary energy demandsand they are responsible for the major production of greenhousegases, leading to a number of negative effects, such as climatechange, receding of glaciers, rise in sea level and loss of biodiver-sity [1]. Increasing energy consumption, negative growth of fossilresources and greenhouse gas emissions have led to a move to-wards the improvement of thermodynamic efficiency of the wellestablished processes, along with the development of new energyefficient and cost-effective process technology.

Distillation is the most mature and widely used separation pro-cess in the chemical and allied industries, accounting for 95% of allseparations in chemical process industries [2], and for an estimated10% of the US industrial energy consumption [3]. Furthermore, it isreported [4] that 40% of the energy used by a chemical plant is fordistillation alone. Because of low thermodynamic efficiency, whichis typically in the range of 5 to 20%, and high energy consumption,the distillation has become a potential candidate for thermalintensification.

After the oil crises in the 1970s, the interest in thermal intensi-fication appears to have been resurrected. In separation processes,the major energy costs are associated with compressors, reboilersand condensers cooled with refrigerant. Proposing thermal

integration in fractionation units leads to additional equipmentcosts that are more than offset savings in utility costs. However,because of increasing utility costs at a faster rate than equipmentcosts, along with the environmental alarm due to the greenhousegas emissions, the heat integration approach has received consid-erable research attention in literature and appears to be economi-cally feasible for distillation processes.

Among various heat integrated distillation techniques, the heatpumping system has emerged as one of the widely acceptedschemes for continuous flow distillation columns. In fact, practicalstudies have shown the potential of this strategy to drastically re-duce the net energy consumption and hence emissions of green-house gases. However, continuous efforts need to be devoted tomake the heat pump assisted distillation (HPAD) scheme moreattractive compared to its close competitors. Although a consider-able progress on heat pumping systems is noticed for continuousflow operations, there is almost no research attention paid forbatch processing. It is fairly true that the unsteady state behaviorof the batch operation makes the heat integration more challeng-ing. The objective of this article is to present the recent develop-ments in the field of heat pump assisted distillation technology,particularly vapor recompression column (VRC) and its hybrid con-figurations, and to identify uncovered gaps in this respect.

2. Heat pump assisted distillation (HPAD) columns

As the cost of energy continues to rise, it becomes imperative toimprove overall energy performance of the chemical process units.With this objective, various energy integration techniques for

288 A.K. Jana / Energy Conversion and Management 77 (2014) 287–297

distillation columns have been explored so far seeking lower en-ergy consumption and better profitability. Heat pump assisted dis-tillation (HPAD) column is one of the most promising alternativesfor the conventional distillation column (CDiC) since HPAD has thepotential to separate a mixture with smaller energy consumptioncompared to CDiC.

In a conventional distillation column, the heat is supplied at thebottom reboiler by a hot utility and that is wasted to a cold utilityat the overhead condenser, thus causing a substantial energy deg-radation. An obvious way to reduce the energy consumption is tocouple the condenser and the reboiler which represent the majorsource and sink of energy, respectively. In this light, the integrationbetween a heat pump and the distillation column is well-known asan attractive terminology.

The heat pumping systems, which can be operated in conjunc-tion with the distillation columns, can be conveniently lumped intotwo categories: mechanical heat pump and absorption heat pump.In the mechanical heat pumps, instead of using a separate over-head condenser and bottom reboiler, the vapor stream leavingthe top tray is compressed to a higher pressure and then used toheat the bottom liquid, or the liquid stream leaving the bottomtray is flashed in a pressure reducing valve and then used to coolthe overhead vapor. On the other hand, the later scheme uses aseparate closed loop fluid system to transfer the heat up the tem-perature scale by means of heat of mixing. In this article, at first,selected works on both of these heat pump assisted distillation col-umns and their impact on energy efficiency as well as cost are re-viewed. Subsequently, we turn our special attention on the recentdevelopments of mechanically heat pump assisted VRC scheme forfinding the further research possibilities.

It should be pointed out here that the energetic and economicperformances are somewhat case specific and therefore the per-cent savings shown throughout this paper for several example sys-tems are intended to indicate trends rather than precise figures.

2.1. Absorption heat pump assisted distillation column

The first absorption heat pump machine was made by the LeC-arre brothers in 1859 [5]. A historical review of this heat pump sys-tem dating back to the work of Nairne in 1777 is presented byStephan [6]. Recently, Chua et al. [7] have provided a comprehen-sive update on recent developments in heat pump machines.

As illustrated in Fig. 1, a typical absorption heat pump includesfour main components, namely absorber, desorber (usually calledgenerator), evaporator and condenser. In the working fluid loop,

Fig. 1. A typical absorption heat pump arrangement.

the generator heats up the solution at high pressure and tempera-ture, releasing vapor to the condenser. Subsequently, the conden-sate goes to the evaporator, in which, it evaporates using lowtemperature heat and then it is absorbed in the absorption column.Obviously, the system receives heat in the generator and the evap-orator, and rejects heat in the condenser and the absorber. The richsolution is pumped from the absorber to the generator, where thecycle starts again. In a typical heat pump system, the pressure ele-vation and the corresponding higher boiling point of the workingfluid are effected by an absorber, a generator and an additionalfluid loop (absorbent loop) between these units.

Fonyo et al. [8] have evaluated six different variants of the heatpumping system with reference to the base case column withisomerization reactor. These six schemes include: three forms ofmechanical heat pump system (vapor recompression, bottomflashing and closed cycle), and three modes of absorption heatpump system (single stage with parallel and sequential operations,and double stage parallel operation). It should be noted that thebottom liquid is boiled up with the use of heat exchangers ar-ranged either in series (sequential operation) or parallel (paralleloperation) mode. For the case of C4 splitter, it is reported [8] thatthe lowest cost is reached by using the double stage scheme,although its operation is far more difficult. Heat pump assisted dis-tillation research is also extended to absorption heat transformer(AHT) [9,10], the reverse operation of the absorption heat pump.In the transformer (Fig. 2), the absorber and evaporator operateat higher pressure, whereas the condenser at the lowest pressure.Tufano [10] has shown that the parallel heat pump – transformerallows one to exactly match the heat loads of most distillation col-umns and to reduce the consumption of primary energy by about40%. A systematic comparison is also presented by Fonyo and Ben-ko [11] between the different variants of the absorption andmechanical heat pumps with the transformer arrangement. For aC4 splitter, their economic evaluations show that the AHT is theworst performer and the heat pump with sequential arrangementis the best one. For selecting a suitable scheme, however, a generalguideline is proposed as: (1) larger heat load and smaller columntemperature difference provide shorter payback time for heatpumping, and (2) the absorption heat transformation cycles havean even chance for implementation at larger temperature differ-ence, when the other heat pump configurations are discarded.Ranade and Chao [12] have also detailed the guidelines for theuse of different kinds of heat pumping arrangements. They haveconcluded that if the Carnot efficiency is taken into account, thevapor recompression approach is the most economical solution,but the simplest way of introducing a heat pump into an existingdistillation unit is the closed cycle system with working fluid.However, it is fairly true to say that the performance of the heatpumps is mostly case specific.

Fig. 2. Distillation column in conjunction with an absorption heat transformer [10][A = absorber, B = bottoms, C = condenser, D = distillate, E = evaporator, EC = econ-omizer, F = feed, G = generator].

Fig. 3. Schematic representation of the mechanical heat pump assisted distillationschemes.

A.K. Jana / Energy Conversion and Management 77 (2014) 287–297 289

By combining the absorption and mechanical heat pumps, thehybrid heat pump assisted distillation system has appeared in lit-erature [13–15]. This advanced multiple-stage distillation schemeconsists of the following principal components, namely absorber,generator and vapor recompression units. Minea and Chiriac [16]have explored the feasibility of the hybrid compression/absorptionheat pump for district heating systems. Currently, Li et al. [17] haveevaluated this scheme for the production of freshwater from sea-water by the use of wasteheat from process industry in the Shef-field region, UK, showing a substantial energy savings of 80% andcoefficients of performance (COP) of 3.1–12.1 in different stages.

The absorption heat pumps are mainly used for refrigerationwhere the temperature of the heat source is higher than that inthe heat sink [17]. They can be operated by all kind of thermal en-ergy including waste heat from chemical processes or engines [17]as well as solar energy [18,19]. In order to utilize the wastewater asa heat source in the desalination process, however, the tempera-ture in the heat sink is more than the temperature in the heatsource. It clearly indicates the necessity of an auxiliary heat sourcethat needs to be coupled to the system to raise the required tem-perature. Aiming to enhance the heat source temperature, variouspossibilities have been explored [17]. Among them, the compres-sion/absorption heat pump systems have great potential for usewith the distillation column because of their high performance ra-tio and good energy management [17]. It should be noted thatabsorption heat pumps have been applied extensively in desalina-tion industry [20–23]. The novel application further includes theuse of a two stage compressor heat pump system in restoring theabsorbent used to clean the flue gases in a pulp mill [24].

In recent years, the use of absorption heat transformer is no-ticed in improving the energy efficiency of desalination plants. Cur-rently, Gomri [25] has presented a comparative study between thesingle effect and double effect AHT systems for the production of500 L of drinking water per day from the seawater. A number ofexperimental studies are also reported [26,27] to show the feasibil-ity of AHT technology.

The main difficulty of this heat pumping arrangement is associ-ated with the working fluids. Sulfuric acid–water mixture, used inthe early days of the absorption heat pump technique, has turnedout to be too corrosive and poisonous [6]. Nowadays, the mostwidely used working fluid is perhaps the ammonia–water mixture[17]. However, in spite of the many potential advantages, this pairexhibits some drawbacks, such as [6]: (i) it is perhaps impossible tocompletely remove the water from the evaporator, which leads toraise the evaporation temperature, (ii) ammonia starts decompos-ing above 180 �C, (iii) there is a limit of maximum temperature inthe generator, and (iv) ammonia is poisonous. Sulfur dioxide andpure ammonia [5,15], which act as a refrigerant, are also poison-ous. Some potential working pairs (working fluid/absorbent)involving chlorofluorocarbons (CFCs) have been investigated inlaboratory size units. Because of current controversy over CFCsand ozone layer depletion, there is likely to be only limited scopefor pairs involving CFCs. When water absorbed by lithium bromideis utilized [21–23], the safety problem may be solved, but otherdifficulties such as crystallization, arise. Some commercial modelsof absorption heat transformers operating with water–LiBr are inuse [28]. Several other working fluids, such as water–LiCl, water–LiCl/LiBr pairs [28], aqueous NaOH [29], aqueous CaCl2 and CaCl2/LiCl solutions [30], and their merits and demerits are extensivelycovered in literature.

In the view of environmental advantages of the absorption heatpump systems and, if the question for primary energy consump-tion is posed, no doubt the absorption systems will gain moreimportance in the near future. The scope for the absorption heatpump must be further broadened if environmentally friendlyworking pairs are identified.

2.2. Mechanical heat pump assisted distillation column

The mechanical heat pumps are electrically driven vaporrecompression types. Based on the concept popularized in the early1950s by Freshwater [31], subsequently Null [32] has proposedthree basic schemes, namely direct vapor recompression, bottomflashing and external vapor recompression. As shown in Fig. 3, allthree mechanical heat pump configurations use an expansion valveand a compressor to alter condensing and/or boiling temperaturesso that the heat rejected in the overhead condenser can be reusedto provide the heat needed in the bottom reboiler.

In the direct vapor recompression column (VRC), the overheadvapor is compressed to a higher pressure to utilize its latent heatfor bottoms liquid reboiling. The condensate leaving the reboileris then flashed across a throttling valve to column top pressurefor providing reflux and distillate. In the bottom flashing, the bot-toms liquid is expanded to a pressure corresponding to a saturationtemperature of the distillate and used as a cooling medium in theoverhead condenser. On the other hand, the external vapor recom-pression, where the heat pump works between the condenser andthe reboiler of a distillation column using some sort of workingfluid, is known as a closed system. Obviously, the whole absor-ber/generator system of absorption heat pump system shown inFig. 1 replaces the compressor of mechanical heat pump system.

When the bottoms product is a good refrigerant, the distillationcolumn with bottom flashing arrangement is a possible candidatefor enhancing thermodynamic efficiency. Moreover, like othermechanical heat pumping structures, this scheme shows its poten-tial in reducing energy consumption, particularly for the separationof mixtures with close boiling points. It is experienced that whenthe bottoms liquid passes through an expansion value, someamount of liquid is most likely to get vaporized. This, in turn, leadsto reduce the rate of top vapor condensation mainly due to thereduction of heat receiving capacity of the flashed vapor over its li-quid state. This problem is further strengthened when the pressurereduction in the valve has increased, i.e. when the boiling pointtemperatures of the components to be separated are far apart. Itshould be highlighted that if the additional heat added during isen-tropic compression is not sufficient to make up the difference be-tween reboiler and condenser duties, an auxiliary steam-heatedreboiler is required to employ, thereby enhancing both the operat-ing and capital costs. Several research groups have evaluated thisscheme in terms of thermodynamic efficiency and overall cost.

Fig. 5. A closed-system configuration of a combined overall heat pump system andintermediate heat exchangers.

290 A.K. Jana / Energy Conversion and Management 77 (2014) 287–297

Importantly, Henley and Seader [33] have presented the applica-tion of the heat pump with reboiler liquid flashing for the separa-tion of propylene–propane (P–P) mixture and shown its maximumthermal efficiency in comparison with other two mechanical sys-tems. Fonyo et al. [8] have compared six heat pump assisted distil-lation columns (3 absorption heat pumps and 3 mechanical heatpumps) for the case of C4 separations and observed that the bottomflashing scheme is the worst economic performer. Again, for sepa-rating a close boiling mixture of i-butane/n-butane, Diez et al. [34]have seen a competitive performance between the VRC and bottomflashing. All these results confirm that the bottom flashing is not agood option when the temperature difference between the over-head and the bottom of the column is reasonably large.

Lynd and Grethlein [35] have proposed different ways ofaccomplishing the intermediate heating and cooling in a distilla-tion process under closed system (i.e. external vapor recompres-sion) framework. Their distillation configuration (Fig. 4),consisting of intermediate heat pumps and optimal sidestream re-turn, allows heat to be moved between points in a distillation col-umn with greater efficiency than several other methods ofemploying heat pumps for distillation. Subsequently, Bjorn et al.[36] have extended this scheme with the additional inclusion ofoverhead condenser and bottom reboiler in the closed system(Fig. 5). Using a mixture of CFC-12 and CFC-114 as a working fluid,it is demonstrated that the addition of top condenser and bottomreboiler to intermediate heat exchangers in the closed cycle systemleads to enhance the energy efficiency from 30% to 75%. Interestedreaders may consult the work of Mizsey and Fonyo [37] for a sys-tematic design methodology for the energy integrated distillationsystem enhanced by closed cycle heat pumping. However, thisexternal vapor recompression scheme, like the absorption heatpump system, involves the use of working fluid and hence suffersfrom the same drawbacks associated with the working pair. Thisclosed system approach is generally preferred when the columnfluid is corrosive or is not a good refrigerant [38].

Several research groups are actively involved in making the di-rect VRC technology more attractive from the early 1970s to tilldate. Danziger [39] has studied distillation columns with vaporrecompression and based on his result, the energy saved is over80% compared to a conventional standalone column. Comparingthe most frequently used single compressor and double compres-sor assisted VRC schemes, Quadri [40] claims that the formerscheme is about 50% cheaper than its double compressor counter-part in case of the splitting of propylene–propane system, a closeboiling mixture. Interestingly, based on a Union Carbide plant, Par-ker [41] has arrived at the opposite conclusion, i.e. two stage heat

Fig. 4. A closed-system configuration with optimal return of the side-stream.

pump compressor case is cheaper than the single compressor case.Annakou and Mizsey [42] have further studied the VRC schemedealing with P–P system and found that the annual costs get re-duced by 37%. Their investigation also shows that the heat pumpassisted distillation column of vapor recompression type mini-mizes about 60% of the flue gas emissions. The application ofVRC strategy is extended to ethylbenzene/xylene and ethylben-zene/styrene separations, showing a substantial savings [43]. Onthe other hand, Canales and Marquez [44] have designed and builta laboratory-scale vapor recompression column for separating abinary mixture of ethanol–water. They have reported a reductionin energy consumption ranging from 45% to 56%, as compared tothe conventional column. As mentioned previously, Diez et al.[34] have selected an i-butane/n-butane mixture to compare thedirect VRC, bottom flashing and absorption heat pumps. Perform-ing simulation experiments, it is shown that the distillation withboth top vapor recompression and bottom flashing configurationsallow reduction of operating costs by 33% and 32%, and capitalcosts by 9% and 10%, respectively. They have concluded that theabsorption heat pump is not worthy for this close boiling systembecause of its large steam consumption compared to the CDiC col-umn. Very recently, Kiss et al. [45] have proposed a set of guide-lines to select the most promising thermally integrateddistillation column based on the following criteria: type of separa-tion tasks, product flow and specifications, operating pressure, dif-ference in boiling points, reboiler duty and its temperature level.

In addition to the economic feasibility study of VRC, this schemehas been a subject of widespread research, focusing on design andoptimization (e.g. [40,43,46,47]), modeling (e.g. [48,49]), operabil-ity analysis (e.g. [42,50]) and control (e.g. [38,51–53]).

The direct vapor recompression machine is the simplest appli-cation of heat pumps in distillation [54] and perhaps the most pop-ular all over the world [15]. In comparison with the absorptionheat pump, the VRC offers a number of appealing advantages, suchas simple structure, small ground space requirement, ease of de-sign and operation, low initial capital investment and no involve-ment of working fluid that creates a lot of troubles. In thisarticle, the vapor recompression distillation has been selected asa potential candidate for review to explore the possibilities of fur-ther advancements.

3. Heat integration indistillation column: emerging approaches

Among the various energy integration techniques scrutinizedfor distillation processes, most important ones include dividing

Fig. 7. Schematic representation of the HIDiC scheme.

A.K. Jana / Energy Conversion and Management 77 (2014) 287–297 291

wall column (DWC) [55–59], internally heat integrated distillationcolumn (HIDiC) [54,60–66] and of course, heat pump assisted VRCscheme [8,33,34,53,67]. After several decades of research, the di-vided wall column (Fig. 6), which integrates two columns of a Pet-lyuk system into one column shell, has been successfullycommercialized. At present, there are more than 70 packed DWCcolumns operated by BASF worldwide [68]. Recently, DWCs makea successful inroad into the refinery world dominated by complexcolumns, and this is becoming a fast developing application field. Itis true that prediction of overall performance is becoming a routinecalculation; however, the predictive models capable of dimension-ing a DWC are still not publicly available [68].

The DWC approach, which is applicable to a specific class of dis-tillation columns, is capable of reducing the energy requirement byaround 30% compared to its conventional two-column configura-tions. Aiming to extend the heat integration concept to a generalclass of distillation processes, the HIDiC scheme (Fig. 7) that com-bines the vapor recompression and diabatic operation has ap-peared with greater promise [69]. An excellent overview of theHIDiC structures can be found in Nakaiwa et al. [70] and Jana [3],and references therein. Performing bench-scale experimental testsfor the separation of a binary mixture of benzene and toluene, it isshown [61] that the HIDiC column can achieve more than 40%reduction in energy consumption. Furthermore, Horiuchi et al.[71] have operated a HIDiC pilot plant at zero external reflux con-dition, and claimed more than 50% savings in energy requirement.Currently, many pilot and industrial-scale projects of HIDiCs areunderway in Japan and in the Netherlands [68].

In HIDiC column, the vapor flow decreases from the bottom tothe top of the rectifier and increases as it flows up towards thetop of the stripper. Usually, the vapor inflow rate to the compressorof a HIDiC is larger than that of a typical vapor recompression col-umn. On the other hand, the VRC involves comparatively largecompression ratio (CR). Although the small vapor flow throughthe compressor can provide benefits for the VRC, the large CR hasa negative impact on the compressor power requirement. It is awell-known fact that the electricity required for driving the com-pressor is several times more expensive than the thermal utilityused to run the reboiler as well as condenser. However, in compar-ison with VRC, the HIDiC column can achieve better economic ben-efits owing to its lower compression ratio [72]. If this is so,

Feed

Bottoms

Side product

Distillate

Fig. 6. Schematic representation of the divided wall column (DWC).

naturally one question arises: why we should go for the VRC?We can find the answer from:

In the case of a stand-alone unit or where there are severe restric-tions on the integrability of the distillation column, the realizationof heat pump assisted distillation is the most promising energy sav-ing technique.

Fonyo and Benko [11]

4. Can we make the VRC scheme a strong competitor to theHIDiC column?

Earlier, it was highly recommended to exhaust the thermal inte-gration possibilities first before the use of VRC since the thermalintegration is usually cheaper and more economical than heatpumping [11]. Even before adopting the VRC scheme, we shouldtake into consideration its limitation that the VRC is an economicway to conserve energy when the temperature difference betweenthe overhead and bottom of the column is reasonably small [42].However, these conceptions concerning the limitation of VRC tech-nology have changed with time and now we are in a position torealize that no single heat integration scheme is always the mostenergy efficient [54]. It is worth noticing that the advanced formsof VRC scheme have proved to be a strong competitor to the HIDiCcolumn and in many situations, even they perform better.

For boosting the thermodynamic efficiency of the classical VRCcolumn, the use of intermediate heat exchangers is introduced along back by Flower and Jackson [73]. It is fairly true that to supplyheat at any point in the lower part of the column, the overhead va-por should be compressed to such a pressure that there exists acertain driving force between the saturation temperature of thecompressed vapor and the temperature at the point in question.In order to supply heat to a number of intermediate points by com-pressing parts of the overhead vapor stream to appropriate pres-sures, they [73] have suggested the employment of a multistagecompression system.

In fact, the use of intermediate heat exchangers in regular dis-tillation column is beneficial, particularly when the componentsbeing separated have widely different boiling points. Luyben [74]has designed a conventional distillation process with intermediatereboilers for separating a wide boiling mixture, showing a 6.6%lower total annual cost. Recently, Jana and Mane [67] have evalu-ated the VRC scheme having intermediate reboilers (Fig. 8) for a to-

Fig. 8. Heat pump assisted vapor recompressed RD column with intermediatereboiler [67].

292 A.K. Jana / Energy Conversion and Management 77 (2014) 287–297

tal reflux multiple feed reactive distillation (RD) column. For ethyl-ene glycol system, a wide boiling mixture case, this heat pump as-sisted column appears overwhelmingly superior to itsconventional counterpart securing an energy savings of 46.2%and a payback period of 2.74 yr. They have further commented thatit is economical to use the compressed overhead vapor as a heatingmedium in the intermediate reboiler and steam in the bottomreboiler; this is exactly what Flower and Jackson [73] have realized.Now, it can be concluded that the VRC configuration is capable ofachieving thermal efficiency and cost benefits for all types of mix-tures, including close-boiling and wide-boiling components.

Very recently, Kumar et al. [75] have explored and analyzedvarious heat pump arrangements with intermediate reboiler(s) un-der the VRC framework. An industrial RD column producing ethyltert-butyl ether (ETBE) is simulated to illustrate the proposedschemes for the separation of a mixture with widely different boil-ing points. The multi-stage vapor recompression column shown inFig. 9, which addresses a number of practical concerns, secures asubstantial energy savings (= 50.60%) and a reasonably low pay-back period (= 3.23 yr).

Shenvi et al. [54] have worked on developing the multi-stagevapor recompression scheme with intermediate exchangers for abinary distillation column. Several alternative configurations ofVRC have also been developed to perform a comparative studywith the HIDiC column. The authors have finally come to the con-clusion that no single heat integration scheme is always the mostenergy efficient. For an economically optimal distribution of inter-mediate heat exchanging arrangements, one may consult theguidelines proposed by Agrawal and his coworkers [76,77].

Interestingly, in spite of the encouraging outcomes, no indus-trial application of HIDiC column exists on plant scale [78], andone of the primary reasons lies in its complex design and structure[79]. Actually, the HIDiC design requires the implementation ofinternal heat exchangers along the height of the column that is stilla challenging problem in the aspect of equipment design. However,it is inspected by several research groups [54,66,80,81] that thereduction of heat transfer locations to a small number has a negli-gible impact on the economic performance. For example, Harwardtand Marquardt [78] have shown that the cost-optimal HIDiC de-signs require only a few heat exchange locations. Even, it is sug-gested to use a single heat exchanger in the HIDiC configuration,which eventually gives rise to a structure similar to the directVRC scheme. Now, it becomes obvious that to make the HIDiC col-umn implementable in industrial scale, we may need to reconfig-ure its design that tends to a heat integrated configuration closeto the VRC column.

5. Introduction of VRC in HIDiC column: hybrid system

One key approach to improving the thermodynamic efficiencyof many industrial processes is to recover every possible sourcesof waste heat and turn them to useful outputs. It is interesting tonote that because of the operation of HIDiC rectifier at an elevatedpressure, the temperature difference between the rectifier top va-por and stripper bottom liquid may be positive, if not, negativewith a reasonably small magnitude. It opens up the possibility offurther intensification in the HIDiC column by introducing theVRC scheme. As shown in Fig. 10, in this intensified scheme (int-HIDiC), a certain amount of thermal driving force is attempted tomaintain by the use of a second compressor in order to ensurethe optimal use of latent heat of rectifier top vapor for stripper bot-toms liquid reboiling.

This novel combination of internal and external thermal inte-grations in the int-HIDiC technique is first evaluated by Maneand Jana [82]. This hybrid system is demonstrated by a simple bin-ary column for the fractionation of an equimolar benzene/toluenemixture. In comparison with the general HIDiC that shows 19.9%energy savings and a payback period of 6.75 yr, they have foundthat the intensified strategy can significantly improve the effi-ciency of energy utilization (61.12% savings) and cost savings(11.45%).

Subsequently, this concept is further reported by Shenvi et al.[54]. However, they discuss the rational of thermal coupling be-tween the overhead vapor of rectifier and the bottom liquid ofstripper with no internal heat exchangers between two diabaticsections. For this configuration, one is no longer constrained tooperate the entire rectifier at high pressure. The two columnsmay be run at the same pressure, and only the amount of vaporneeded for reflux and boilup needs to be compressed. This avoidscompression of the entire vapor that flows through the rectifier.Obviously, we would expect power savings from this simple heatpump strategy compared to the HIDiC-equivalent scheme.

Recently, Kiran et al. [83] have extended this technique to ex-plore the two forms of int-HIDiC for the fractionation of a multi-component hydrocarbon system. Their intensified scheme isclassified mainly based on the use of number of compressors. Itis examined that the int-HIDiC with single compressor and thatwith double compressor systems appear superior to the generalHIDiC and the conventional column in terms of energy consump-tion and economic figure. In their single compressor scheme, therectifier is operated at a reasonably high pressure so that a certainthermal driving force between the rectifier top and the stripperbottom is maintained. Without running the rectifier at so highpressure, alternatively the same thermal driving force is main-

Fig. 9. Schematic representation of the double-stage vapor recompression RD column with double intermediate reboiler [75] [B = bottoms rate, D = distillate rate,IR = intermediate reboiler, P = pressure, T = temperature, TV = throttling valve, Comp = compressor, V = vapor flow rate, x = liquid phase composition].

A.K. Jana / Energy Conversion and Management 77 (2014) 287–297 293

tained by the employment of a second compressor in the HIDiCwith double compressor system. Among these two investigatedschemes, the authors [83] have shown that the double compressorassisted column provides the maximum energy savings of 59.15%and a least payback time of excess capital (3.44 yr). It should benoted that the single compressor scheme is a feasible option onlywhen there exists a positive thermal driving force between theheat source and the heat sink; otherwise, the driving force has tomake positive by enhancing the compression ratio.

It is worth mentioning that the use of more intensified struc-tures may not always provide cost-effective performance com-pared to a simpler arrangement. In this context, Bjorn et al. [36]have stated that:

The use of more elaborate systems involving intermediate heatexchangers is, theoretically, necessary in order to achieve a higherthermodynamic efficiency; in practice, however, these systems donot always turn out to be economically viable when compared withsimpler arrangements.

Moreover, it is fairly true that the degree of heat integration andcontrollability are likely to have an inverse relation [84]. It is notexpected that one would build a highly energy efficient processthat is very poorly controllable or even uncontrollable. Therefore,

we should take into account the cost and controllability issues to-gether, along with the energetic performance, when we wish tointroduce further intensification in a standard heat integratedcolumn.

6. VRC in batch processing

6.1. Vapor recompressed batch distillation (VRBD)

It is recognized that the heat pump systems are easy to intro-duce and the plant operation is generally simpler compared toother heat integration schemes. In fact, the vapor recompressedcolumn (VRC) designs are often more cost efficient owing to sim-pler equipment [78]. These appealing advantages motivate us toexplore the possibility of VRC applications, particularly in batchprocessing.

It has long been recognized that the batch distillation is less en-ergy efficient than the continuous flow column. As illustrated thevapor recompressed batch distillation (VRBD) configuration inFig. 11, vapor from the top of the batch column is compressed tothe desired pressure (hot stream) and condensed against reboilerliquid (cold stream). This in turn boils the reboiler content, gener-ating vapor that enters the rectification tower. Although the over-

Fig. 10. Schematic representation of the int-HIDiC column [82].

Fig. 11. Schematic representation of the vapor recompressed batch distillation(VRBD) column [L = liquid rate; V = vapor rate].

294 A.K. Jana / Energy Conversion and Management 77 (2014) 287–297

head stream keeps changing its phase to liquid state, it leaves thestill at elevated pressure. Before entering into the reflux drum, thecondensate is therefore depressurized by a pressure relieve valve.

Although the thermal arrangement made in both the VRC schemesoperated in continuous and batch modes seems to be the same, theoperation of VRBD is comparatively much more challenging be-cause of its transient nature. The author of this review and his teammembers are involved in developing the VRC and its hybrid config-urations for batch operations.

Johri et al. [85] are the first to configure the VRC scheme forbatch processing. In their strategy, the thermal driving force be-tween the compressed top vapor and the reboiler liquid is at-tempted to keep constant throughout the unsteady stateoperation. In order to meet this operational objective, the compres-sor needs to be operated at a variable speed mode and therefore,they prefer to call this structure as the variable speed vapor recom-pressed batch distillation (variable speed VRBD). To ensure the opti-mal use of internal heat source, an open-loop control policy isfurther proposed by the authors for the VRBD. Along with the CR,this control mechanism suggests to adjust either the overhead va-por splitting or the external heat supply to the reboiler. For a reac-tive distillation (RD) example, Johri et al. [85] have shown that thevariable speed VRBD is capable of reducing about 65.85% energyconsumption. The attractiveness of this new thermally coupledstructure is also measured by its payback period of excess capital(4 yr).

Subsequently, several interesting applications of the variablespeed VRBD structure are started reporting in literature. Impor-tantly, Babu et al. [86] have synthesized this heat integratedscheme for a ternary batch distillation with a side withdrawal,achieving a 85.97% savings in energy efficiency and 44.67% in totalannualized cost (TAC). For the case of a middle vessel batch distil-

C2

Distillate

Heat C1

Condenser

Overhead vapor

A.K. Jana / Energy Conversion and Management 77 (2014) 287–297 295

lation, the variable speed mechanism is also applied [87] and thisexample system provides a sharp reduction in energy consumption(60%) and a payback time of 2.73 yr.

Although the VRC in conjunction with a variable speed com-pressor is much more thermodynamically efficient for batch pro-cessing than the conventional batch distillation (CBD), the majorcause of concerns associated in its application is the operation ofcompressor at varying compression ratio. For smooth operationof heat pump in a thermally coupled batch splitter, a relativelysimple VRBD configuration that runs at a fixed CR value is subse-quently proposed by Khan et al. [88]. By separating a binary mix-ture of wide boiling components, they have quantitatively shownhow closely the reversible batch operation can be approximatedby using the direct compression of overhead vapor. It should benoted that the variable speed VRBD shows a little improvementover its fixed speed counterpart in terms of energy efficiency andcost, but at the cost of an increased operational complexity.

Fig. 13. Schematic representation of the VRC-HIBDJS scheme [C = compressor].

6.2. Introduction of VRC in an internally heat integrated batchdistillation with a jacketed still (HIBDJS): hybrid system

Fig. 12 schematically illustrates the principles of an internallyheat integrated batch distillation with a jacketed still (HIBDJS).As shown, this thermally coupled scheme uses a jacket as a reboiler(or still) that surrounds the rectifying tower. The vapor produced inthis concentric reboiler is compressed and then introduced at thebottom of the rectifier. As a consequence, there exists a pressuredifference (temperature difference) between the rectifier and jack-eted reboiler. Accordingly, a certain amount of energy is exchangedfrom the HP rectifier to the LP reboiler through the internal walland brings the downward liquid flow for the former and upwardvapor flow for the latter. By this way, the reboiler and condenserheat loads can get lowered.

This new heat integrated batch distillation is originally config-ured by Takamatsu et al. [89]. After a long gap, Maiti et al. [90]have systematized their idea and clarified the advantages of thisapproach through numerical simulations. The authors have re-ported their findings for the separation of a binary mixture (etha-nol/water) that the potential energy integration leads to achievingabout 56.10% energy savings and 40.53% savings in total annual-ized cost.

For boosting further the thermodynamic and economic perfor-mance, the same research group [91] has proposed a novel combi-nation of internal and external heat integrations introducing directvapor recompression approach in the HIBDJS scheme (Fig. 13). Inaddition to the heat transferred from HP rectifier to LP still throughthe internal wall, the latent heat of overhead vapor is also utilizedfor liquid reboiling. Aiming to run the column at a constant reboiler

Distillate

Heat

Compressor

Condenser

Fig. 12. Schematic representation of the HIBDJS scheme.

duty throughout the entire batch operation, an open-loop controlpolicy needs to be devised because of the dynamic behavior ofbatch processing. This hybrid VRC-HIBDJS scheme demonstratedby a butyl acetate RD column shows a dramatic reduction of en-ergy consumption by 75% and a payback time to 1.74 yr.

7. Scope of future research

7.1. VRC in continuous processing

The heat pump assisted VRC column has been studied exten-sively, particularly for separating the close boiling mixtures. Inthe recent past, the use of intermediate reboiler(s) in VRC technol-ogy is thoroughly investigated with several numerical examples forthe separation of components having widely different boilingpoints. Till now, however, no industrial application of this multi-stage VRC with intermediate heat exchanger(s) exists accordingto the author’s knowledge. Truly speaking, the optimal integrationof the heat pumping system with a distillation column still remainsa challenging R&D task.

Efficient use of energy in distillation columns is crucial to thereduction of net energy consumption and hence emissions ofgreenhouse gases. Recent advances have shown that an intensifiedenergy integrated distillation configuration leads to a significantenergy and thus cost savings. However, this cost benefit comes atthe expense of operating and control challenges. Tight couplingof various possible heat sources and heat sinks results in the reduc-tion of available degrees of freedom and in feedback interactions,adding further complexities in the process dynamics and control.Although a lot of progress has been made on VRC technology forcontinuous flow distillation columns, some more efforts need tobe devoted to improve their industrial use for separating a widerange of mixtures, including wide boiling mixtures, and theirclosed-loop control performance to run the columns at optimalstates.

7.2. VRC in batch processing

With the eventual acceptance of a carbon/energy tax around theworld, energy conservation has become a major concern in manyindustrial applications. Since the VRC column operated in continu-ous mode has shown promising potential, even in industrial prac-tice, in terms of both thermodynamic efficiency and cost, it istherefore strongly suggested to extend this technology for wide-spread use in batch processing.

296 A.K. Jana / Energy Conversion and Management 77 (2014) 287–297

A remarkable shift toward batch distillation technology hasbeen noticed during the last two decades because of the exponen-tial growth of the fine-chemical, food, pharmaceutical and bio-chemical industries. As presented earlier, the development ofVRC technology for batch processing has just initiated. Therefore,there is enormous scope and demand for further research in anumber of directions, including the equipment design, processoptimization, thermodynamic and economic feasibility with exper-imental verification, and controllability analysis.

8. Conclusions

This review paper has portrayed heat pump assisted distillationas an energy-efficient separation technology with enormous po-tential to contribute to chemical, refinery, petrochemical, pharma-ceutical and biochemical industries. Introducing the heat pumpingsystem with its past progresses, it is demonstrated through variousliterature sources how recent efforts have improved the distillationcolumn energy efficiency by the use of heat pump with intermedi-ate heat exchangers in conjunction with multi-stage compressionsystem. Then the focus is turned to review the various recentlydeveloped hybrid VRC based thermally coupled systems, whichhave further improved efficient use of thermal heat, reduced theTAC as well as carbon emission.

Beside the reduction of energy consumption and thereby, over-all cost, the heat pump systems can be considered in grass-root orretrofitting design because of ease of their introduction, simplestructure and operation. Keeping these appealing advantages ofVRC in mind, it is suggested that continuous efforts need to be de-voted in exploring its widespread use, particularly in industrialapplications and batch processing. It is worth noticing that thedevelopment of vapor recompressed batch distillation has juststarted and hence a number of potential issues are still remaineduntouched.

Through this review paper, we hope to convey one key messagethat further efforts in improving the heat pump assisted distillationtechnology will optimize the energy use and reduce the carbonfootprint of many chemical, pharmaceutical, biochemical andrefinery industries.

References

[1] Nigam PS, Singh A. Production of liquid biofuels from renewable resources.Prog Energy Combust Sci 2011;37:52–68.

[2] Engelien HK, Skogestad S. Selecting appropriate control variables for a heatintegrated distillation system with prefractionator. Comput Chem Eng2004;28:683–91.

[3] Jana AK. Heat integrated distillation operation. Appl Energy 2010;87:1477–94.[4] Humphrey J. Separation process technology. New York: McGraw-Hill; 1997.[5] Lazzarin RM. Commercially available absorption heat pumps: some

experimental tests. Int J Refrig 1988;11:96–9.[6] Stephan K. History of absorption heat pumps and working pair developments

in Europe. Int J Refrig 1983;6:160–6.[7] Chua KJ, Chou SK, Yang WM. Advances in heat pump systems: a review. Appl

Energy 2010;87:3611–24.[8] Fonyo Z, Kurrat R, Rippin DWT, Meszaros I. Comparative analysis of various

heat pump schemes applied to C4 splitters. Comput Chem Eng 1995;19:S1–6.[9] Berntsson T, Holmberg P, Wimby M. Research activities on heat transformer at

Chalmers University of Technology, Sweden. In: Zegers P, Miriam J, editors.Proceedings of the workshop on ‘‘Absorption Heat Pumps’’. Directorate-General, Research, Science and Development, Commission of the EuropeanCommunities, London; 1988.

[10] Tufano V. Heat recovery in distillation by means of absorption heat pumps andheat transformers. Appl Therm Eng 1997;17:171–8.

[11] Fonyo Z, Benko N. Comparison of various heat pump assisted distillationconfigurations. Trans Inst Chem Engrs 1998;76:348–60.

[12] S. Ranade, Y. Chao, Industrial heat pumps: where and when?. HydrocarbProcess 1990;(October):71–3.

[13] D. Hodgett, L. Ahlby, The effect of the properties of the refrigerant and solventon the compression/absorption cycle. In: Proc. of XVII int congress of refrig,Vienna, 24–29 August 1987, IIR, Paris, V.E. 664-71; 1987.

[14] Morawetz E. Sorption–compression heat pumps. Int J Energy Res1989;13:83–102.

[15] Tarique SM, Siddiqui MA. Performance and economic study of the combinedabsorption/compression heat pump. Energy Convers Manage 1999;40:575–91.

[16] Minea V, Chiriac F. Hybrid absorption heat pump with ammonia/watermixture: some design guidelines and district heating application. Int J Refrig2006;29:1080–91.

[17] Li H, Russell N, Sharifi V, Swithenbank J. Techno-economic feasibility ofabsorption heat pumps using wastewater as the heating source fordesalination. Desalination 2011;281:118–27.

[18] Alarcón-Padilla DC, García Rodríguez L. Application of absorption heat pumpsto multi-effect distillation: a case study of solar desalination. Desalination2007;212:294–302.

[19] Li C, Goswami DY, Shapiro A, Stefanakos EK, Demirkaya G. A new combinedpower and desalination system driven by low grade heat for concentratedbrine. Energy 2012;46:582–95.

[20] Al-Juwayhel F, El-Dessouky HT, Ettouney HM. Analysis of single-effectevaporator desalination systems driven by vapor compression heat pumps.Desalination 1997;114:253–75.

[21] Mandani F, Ettouney H, El-Dessouky H. LiBr–H2O absorption heat pumpfor single-effect evaporation desalination process. Desalination2000;128:161–76.

[22] Wang Y, Lior N. Proposal and analysis of a high-efficiency combineddesalination and refrigeration system based on the LiBr–H2O absorptioncycle-Part 1: system configuration and mathematical model. Energy ConversManage 2011;52:220–7.

[23] Wang Y, Lior N. Proposal and analysis of a high-efficiency combineddesalination and refrigeration system based on the LiBr–H2O absorptioncycle. Part 2: thermal performance analysis and discussions. Energy ConversManage 2011;52:228–35.

[24] Hektor E, Berntsson T. The role of processes integration in CCS systems in oilrefineries and pulp mills. In: Varbanov P, Klemes J, Bulatov I, editors. Energyfor sustainable future, EMINENT 2 workshop, Veszprém Hungary; 2008.

[25] Gomri R. Thermal seawater desalination: possibilities of using single effect anddouble effect absorption heat transformer systems. Desalination2010;253:112–8.

[26] Rivera W, Siqueiros J, Martinez H, Huicochea A. Exergy analysis of a heattransformer for water purification increasing heat source temperature. ApplTherm Eng 2010;30:2088–95.

[27] Rivera W, Huicochea A, Martinez H, Siqueiros J, Juarez D, Cadenas E. Exergyanalysis of an experimental heat transformer for water purification. Energy2011;36:320–7.

[28] Pataskar SG, Adyanthaya SD, Devotta S, Holland FA. Performance of anexperimental absorption heat transformer using aqueous LiBr, LiCl, and LiBr/LiCl solutions. Ind Eng Chem Res 1990;29:1658–62.

[29] Smith E, Carey CO.B. Thermal transformers for upgrading industrial wasteheat. In: Proc int symp on industrial heat pumps, Coventry, England. BHRA,UK; paper H1; 1982.

[30] Siddig Mohammed BE, Watson FA, Holland FA. Study of the operatingcharacteristics of a reversed absorption heat pump (heat transformer). ChemEng Res Des 1983;61:283–9.

[31] Freshwater DC. Thermal economy in distillation. Trans Inst Chem Engrs1951;29:149–60.

[32] Null HR. Heat pumps in distillation. Chem Eng Prog 1976;73:58–64.[33] Henley EJ, Seader JD. Equilibrium-stage separation operations in chemical

engineering. New York: John Wiley & Sons; 1981.[34] Diez E, Langston P, Ovojero G, Ramero MD. Economic feasibility analysis of

heat pumps in distillation to reduce energy use. Appl Therm Eng2009;29:1216–23.

[35] Lynd LR, Grethlein HE. Distillation with intermediate heat pumps and optimalsidestream return. AIChE J 1986;32:1347–59.

[36] Bjorn I, Gren U, Strom K. A study of a heat pump distillation column system.Chem Eng Process 1991;29:185–91.

[37] Mizsey P, Fonyo Z. Energy integrated distillation system design enhanced byheat pumping. Distillation and absorption 1992, IChemE; 1992. 1369–76.

[38] Jogwar SS, Daoutidis P. Dynamics and control of vapor recompressiondistillation. J Process Control 2009;19:1737–50.

[39] Danziger R. Distillation columns with vapor recompression. Chem Eng Prog1979;(September).

[40] Quadri GP. Use of heat pump in P–P splitter, part 1: process design, part 2:process. optimization. Hydrocarb Process 1981;60:119–26, 147–51.

[41] Parker J. Heat pumps show promise for industry. Oil Gas J1978;(December):76–80.

[42] Annakou O, Mizsey P. Rigorous investigation of heat pump assisted distillation.Heat Recovery Syst CHP 1995;15:241–7.

[43] Ferre JA, Cestells F, Flores J. Optimization of a distillation column with a directvapor recompression heat pump. Ind Eng Chem Process Des Dev1985;24:128–32.

[44] Canales ER, Marquez F. Operation and experimental results on a vaporrecompression pilot–plant distillation column. Ind Eng Chem Res1992;31:2547–55.

[45] Kiss AA, Flores Landaeta SJ, Infante Ferreira CA. Towards energyefficient distillation technologies – making the right choice. Energy2012;47:531–42.

[46] Fitzmorris KE, Mah RSH. Improving distillation column design usingthermodynamic availability analysis. AIChE J 1980;26:265–73.

[47] Guxens S, Salvado J, Ferre JA, Castells F. Optimal design of a distillation columnwith vapor recompression. Distill Absorp 1987;2:B291–304.

A.K. Jana / Energy Conversion and Management 77 (2014) 287–297 297

[48] Brousse E, Claudel B, Jallut C. Modeling and optimization of the steady stateoperation of a vapor recompression distillation column. Chem Eng Sci1985;40:2073–8.

[49] Oliveira SBM, Marques RP, Parise JAR. Modeling of an ethanol–waterdistillation column with vapor recompression. Int J Energy Res2001;25:845–58.

[50] Enweremadu C, Waheed A, Ojediran J. Parametric study of an ethanol–waterdistillation column with direct vapour recompression heat pump. EnergySustain Dev 2009;13:96–105.

[51] Hernandez E. Feasibility analysis, dynamics and control of distillation columnswith vapor recompression. PHD Thesis, Louisiana State University, BatonRogue, LA; 1981.

[52] Muhrer CA, Collura MA, Luyben WL. Control of vapor recompressiondistillation columns. Ind Eng Chem Res 1990;29:59–71.

[53] Jogwar SS, Baldea M, Daoutidis P. Tight energy integration: dynamic impactand control advantages. Comput Chem Eng 2010;34:1457–66.

[54] Shenvi AA, Herron DM, Agrawal R. Energy efficiency limitations of theconventional heat integrated distillation column (HIDiC) configuration forbinary distillation. Ind Eng Chem Res 2011;50:119–30.

[55] Petlyuk FB, Platanov VM, Slavinskii DM. Thermodynamically optimal methodfor separating multicomponent mixtures. Int Chem Eng 1965;5:555–61.

[56] Dünnebier G, Pantelides CC. Optimal design of thermally coupled distillationcolumns. Ind Eng Chem Res 1999;38:162–76.

[57] Kolbe B, Wenzel S. Novel distillation concepts using one-shell columns. ChemEng Process 2004;43:339–46.

[58] Kaibel B, Jansen H, Zich E, Olujic Z. Unfixed dividing wall technology for packedand tray distillation columns. Distill Absorp 2006;152:252–66.

[59] Kiss AA, Rewagad RR. Energy efficient control of a BTX dividing-wall column.Comput Chem Eng 2011;35:2896–904.

[60] Liu X, Qian J. Modeling, control, and optimization of ideal internal thermallycoupled distillation columns. Chem Eng Technol 2000;23:235–41.

[61] Naito K, Nakaiwa M, Huang K, Endo A, Aso K, Nakanishi T, et al. Operation of abench-scale ideal heat integrated distillation column (HIDiC): an experimentalstudy. Comput Chem Eng 2000;24:495–9.

[62] Gadalla MA, Olujic Z, Jansens PJ, Jobson M, Smith R. Reducing CO2 emissionsand energy consumption of heat-integrated distillation systems. Environ SciTechnol 2005;39:6860–70.

[63] Lee JY, Kim YH, Hwang KS. Application of a fully thermally coupled distillationcolumn for fractionation process in naphtha reforming plant. Chem EngProcess 2004;43:495–501.

[64] Fukushima T, Kano M, Hasebe S. Dynamics and control of heat integrateddistillation column (HIDiC). J Chem Eng Jpn 2006;39:1096–103.

[65] Huang K, Shan L, Zhu Q, Qian J. Adding rectifying/stripping section type heatintegration to a pressure-swing distillation (PSD) process. Appl Therm Eng2008;8:923–32.

[66] Suphanit B. Optimal heat distribution in the internally heat-integrateddistillation column (HIDiC). Energy 2011;36:4171–81.

[67] Jana AK, Mane A. Heat pump assisted reactive distillation: wide boilingmixture. AIChE J 2011;57:3233–7.

[68] Olujic Z, Jodecke M, Shilkin A, Schuch G, Kaibel B. Equipment improvementtrends in distillation. Chem Eng Process 2009;48:1089–104.

[69] Olujic Z, Fakhri F, de Rijke A, De Graauw J, Jansens PJ. Internal heatintegration—the key to an energy-conserving distillation column. J ChemTechnol Biotechnol 2003;78:241–8.

[70] Nakaiwa M, Huang K, Endo A, Ohmori T, Akiya T, Takamatsu T. Internally heat-integrated distillation columns: a review. Trans Inst Chem Engrs2003;81:162–77.

[71] Horiuchi K, Yanagimoto K, Kataoka K, Nakaiwa M, Iwakabe K, Matsuda K.Energy saving characteristics of the internally heat integrated distillationcolumn (HIDiC) pilot plant for multicomponent petroleum distillation. J ChemEng Jpn 2008;41:771–8.

[72] Olujic Z, Sun L, de Rijke A, Jansens PJ. Conceptual design of an internally heatintegrated propylene–propane splitter. Energy 2006;31:3083–96.

[73] Flower JR, Jackson R. Energy requirements in the separation of mixtures bydistillation. Trans Inst Chem Engrs 1964;42:T249–58.

[74] Luyben WL. Design and control of distillation columns with intermediatereboilers. Ind Eng Chem Res 2004;43:8244–50.

[75] Kumar V, Kiran B, Jana AK. A novel multi-stage vapor recompression reactivedistillation with intermediate reboilers. AIChE J; 2013 (in press). http://dx.doi.org/10.1002/aic.13862.

[76] Agrawal R, Herron DM. Efficient use of an intermediate reboiler or condenserin a binary distillation. AIChE J 1998;44:1303–15.

[77] Agrawal R, Herron DM. Intermediate reboiler and condenser arrangement forbinary distillation columns. AIChE J 1998;44:1316–24.

[78] Harwardt A, Marquardt W. Heat-integrated distillation columns: vaporrecompression or internal heat integration? AIChE J 2012;58:3740–50.

[79] Chen H, Huang K, Wang S. A novel simplified configuration for an ideal heat-integrated distillation column (ideal HIDiC). Sep Purif Technol2010;73:230–42.

[80] Huang K, Chen H, Wang S. A design simplification of the ideal heat-integrateddistillation column. In: de Haan AB, Kooijman H, Gorak A, editors. Distillationand absorption, Eindhoven, The Netherlands; 2010. p. 49–54.

[81] Harwardt A, Kraemer K, Marquardt W. Identifying optimal mixture propertiesfor HIDiC application. In: de Haan AB, Kooijman H, Gorak A, editors.Distillation and absorption, Eindhoven, The Netherlands; 2010. p. 55–60.

[82] Mane A, Jana AK. A new intensified heat integration in distillation column. IndEng Chem Res 2010;49:9534–41.

[83] Kiran B, Jana AK, Samanta AN. A novel intensified heat integration inmulticomponent distillation. Energy 2012;41:443–53.

[84] Jana AK, Mali SV. Analysis and control of a partially heat integrated refinerydebutanizer. Comput Chem Eng 2010;34:1296–305.

[85] Johri K, Babu GUB, Jana AK. Performance investigation of a variable speedvapor recompression reactive batch rectifier. AIChE J 2011;57:3238–42.

[86] Babu GUB, Pal EK, Jana AK. An adaptive vapor recompression scheme for aternary batch distillation with a side withdrawal. Ind Eng Chem Res2012;51:4990–7.

[87] Babu GUB, Aditya R, Jana AK. Economic feasibility of a novel energy efficientmiddle vessel batch distillation to reduce energy use. Energy 2012;45:626–33.

[88] Khan MN, Babu GUB, Jana AK. Improving energy efficiency and cost-effectiveness of batch distillation for separating wide boiling constituents. I.Vapor recompression column. Ind Eng Chem Res 2012;51:15413–22.

[89] Takamatsu T, Tajiri A, Okawa K. In proceedings of the chemical engineeringconference of Japan, Nagoya; 1998. p. 628–9.

[90] Maiti D, Jana AK, Samanta AN. A novel heat integrated batch distillationscheme. Appl Energy 2011;88:5221–5.

[91] Maiti D. Heat integrated batch distillation with a jacketed reboiler. PhD Thesis,Indian Institute of Technology, Kharagpur; 2013.