A New Intensified Heat Integration in Distillation Column - American

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Ind. Eng. Chem. Res. 2010, 49, 9534–9541

A New Intensified Heat Integration in Distillation Column Ajay Mane and Amiya K. Jana* Department of Chemical Engineering, Indian Institute of Technology-Kharagpur, West Bengal 721 302, India

In this contribution, a new intensified energy integration technique is introduced for the distillation column. The influence of the proposed intensified heat-integrated distillation column (int-HIDiC) scheme on the energetic and economic aspects is evaluated through intensive comparison against the heat-integrated distillation column (HIDiC) and the conventional stand-alone column. The HIDiC and the conventional distillation column (CDiC) are conceptually designed by the minimization of total annual cost (TAC). Here, two int-HIDiC structures are developed by introducing further thermal coupling between the overhead vapor of rectifying section and the bottom liquid of stripping section of the HIDiC scheme. This intensified energy integration approach reduces the steam consumption in the reboiler and avoids the use of a trim-condenser. For a binary distillation, it is observed that the proposed int-HIDiCs provide positive energy savings and better economic figures than the HIDiC and the conventional column. 1. Introduction Distillation columns are well-known for their high energy consumption. It is notable that more than 70% of the operation costs are caused by the energy expenses.1 Surprisingly, the overall thermodynamic efficiency of a conventional distillation is ∼5%-20%.2 Motivated by these facts, several researchers have focused the attention of their research toward improving distillation technology. The distillation process consumes a great deal of energy that is later degraded to the surroundings as condensing heat. To improve this situation, there is a need to explore the possibility of energy integration that shows potential for energy savings. Beside the reduction of energy consumption, the economic advantage must be ensured before introducing a thermally feasible heat-integrated distillation process. It is a fact that the proper utilization of energy leads to a cleaner environment by minimizing the flue gas emissions that are usually associated with energy consumption. Various energy integration techniques have been proposed in the literature, such as vapor recompression column,3 dividedwall column,4,5 concentric heat-integrated distillation column,6 internally heat-integrated distillation column (HIDiC),7,8 etc. All these methods have their own merits and demerits.9 It is worthwhile to mention the work of Du¨nnebier and Pantelides,5 which considers the optimal design of thermally coupled distillation columns and dividing wall columns using detailed column models and mathematical optimization. It has been shown10,11 that the HIDiC is a promising alternative to the conventional distillation column (CDiC). In this article, a new intensified energy integration structure is introduced for the distillation process. The primary objective of the present work is to explore the economical and operational feasibility of the proposed scheme. Actually, the intensified heatintegrated distillation column (int-HIDiC) is developed by introducing an additional thermal coupling in the HIDiC configuration between the overhead vapor of the rectifier and the bottom liquid of the stripper. In this way, along with the reduction of steam consumption in the reboiler, the use of a trim-condenser can also be avoided. It is observed for the case of a binary distillation column that the two proposed int-HIDiCs * To whom correspondence should be addressed. Tel.: +91-03222283918. Fax: +91-03222-282250. E-mail: [email protected].

provide significant energy savings and better economic figures than both the HIDiC and the CDiC. 2. Process Description 2.1. Conventional Column. In this work, a binary (benzene/ toluene) distillation column is exampled to investigate the performance of the intensified heat integration approach. A typical layout of the representative conventional process is shown in Figure 1. The column has total 26 stages (excluding the total condenser and the reboiler). The numbering of stages starts from the bottom upward. The feed (subcooled liquid) is introduced in stage 13. Conceptual process design is conducted

Figure 1. Schematic of a conventional distillation column (CDiC).

10.1021/ie100942p  2010 American Chemical Society Published on Web 08/25/2010

Ind. Eng. Chem. Res., Vol. 49, No. 19, 2010

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Table 2. Startup Operation of a Typical HIDiC Structure

Table 1. Process Parameters and Steady-State Values parameter

CdiC

HIDiC

step

procedure

feed flow rate feed composition (benzene) top composition (benzene) bottom composition (benzene) distillate rate bottoms rate reflux ratio column diameter total number of trays feed stage stage pressure drop

120 kmol/h 0.5 0.970012 0.029996 60 kmol/h 60 kmol/h 1.235 1.8 m 26 13 0.3 kPa

120 kmol/h 0.5 0.970021 0.029984 60 kmol/h 60 kmol/h 0.3

1 2 3

The heat-integrated column is empty. Feed is introduced into the top tray of the stripping column. Liquid moves downward and the liquid holdup in the trim-reboiler starts to increase. The reboiler has a certain specified volume of liquid and the level controller starts to work. At this time, the heat is introduced into the reboiler and the compressor begins to work. The pressure in the rectifier reaches a prespecified level and the trim condenser starts to work. The pressure is controlled by the trim-condenser duty, and the level control system begins to work. The process is operated under total reflux conditions until the overhead vapor flow rate is equal to a specified value. The product withdrawal is started and the composition controllers are switched on.

by minimizing the total annual cost (TAC), with an assumed payback period of 3 years. The operating parameters and steady state values are detailed in Table 1. 2.2. Heat Integration. The heat integration concept has been applied to the representative distillation column, keeping the input and output specifications identical. The target purity level in the top product is set at 97 mol %. As shown in Figure 2, the HIDiC consists of two separate columns (a rectifier and a stripper). For adjustment of the pressure difference between the rectifying and stripping sections, a compressor and a throttling valve are installed. A selected number of internal tray-to-tray heat exchangers can be used to transfer the heat from the rectifier to the stripper. The trim-reboiler and trim-condenser are required for startup operation of the HIDiC. Table 2 describes the startup operation procedure of a typical HIDiC structure. In the heat-integrated column, the overhead vapor stream of the stripping section is compressed and then introduced at the bottom of the rectifying column. As a result, a pressure

Figure 2. Schematic of a heat-integrated distillation column (HIDiC).

4 5

6

difference exists between the two columns. The bottom liquid of the rectifying section is fed into the top of the stripping section, as is the feed to the stripping column. The pressure of the recycled liquid from the rectifying section is equalized with that of the stripping stage, using a throttling valve. Because of the internal thermal coupling, a certain amount of energy is transferred from the rectifier to the stripper and brings the downward reflux flow for the former and the upward vapor flow for the latter. This results in reduction of the reboiler heat load. However, at the same time, an additional compressor duty is involved in the thermally coupled column. In the HIDiC scheme, the rectifying section that includes the trim-condenser and the stripping section that combines the trimreboiler have the same number of stages (i.e., 13 theoretical stages).

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Figure 3. HIDiC stage temperature profiles (in this figure, the stage numbering in both sections starts from the bottom and increases upward).

2.3. Model Development. The following assumptions are made in deriving the mathematical model for both the CDiC and HIDiC schemes. • Liquid on the tray is perfectly mixed and incompressible. • Vapor holdup in the column is negligible. • Vapor-liquid equilibrium (VLE) is calculated using the Wilson model.12 • Tray pressure drop (0.3 kPa) and efficiency (70%) are constant and the same for all trays. • Liquid hydraulics are calculated from the nonlinear Francis weir formula.12 • For the heat-integrated structure, heat transfer is computed using the term UA∆T, where U denotes the overall heat-transfer coefficient (expressed in units of kW/(m2 K)), A the heat-transfer area (given in units of m2), and ∆T the temperature difference (in Kelvin) between the rectifying tray and the stripping tray. The modeling equations for a typical tray of the heatintegrated column are reported in the Appendix. In the simulation, we consider all the time derivatives equal to zero for producing steady state results. The computer codes have been developed using C language. Note that a pressure of 1 atm is considered to exist for the top stage of the CDiC and that of the HIDiC stripper. 3. Thermodynamic Feasibility of HIDiC When there is no energy coupling between the rectifying and stripping columns of a HIDiC scheme, the reboiler and condenser operate on maximum heat loads. The temperature for each stage in both columns (stripping and rectifying) with no internal tray-to-tray heat transfer is obtained in Figure 3. In this simulation, the total number of stages (nT) is 26, the stage pressure drop (∆P) is 0.3 kPa, the compression ratio (CR) (which is defined as CR ) PR/PS) is 2.1, and the reflux ratio (RR) is 1.235. Figure 3 indicates that, although the temperature driving force varies along the columns, it is always positive between all of the rectifying and stripping column stages. When the rectifier is hotter than the stripper, a heat-integrated column configuration, with respect to design and operation, is thermodynamically feasible. Therefore, the sample distillation column is a suitable case for heat integration. The feasibility regions of energy integration can be determined from the simulated stage temperature profiles. It is noteworthy that thermal coupling should be recommended, taking into account the cost of energy, along with the total cost. For the HIDiC, we consider a typical cutoff value of ∆Tmin ≈

Figure 4. Effect of compression ratio on (A) energy consumption and (B) distillate purity of the HIDiC column.

14 °C. Accordingly, it is suggested to install the 10 internal heat exchangers connected between the rectifying and stripping stages, namely 4-17, 5-18, 6-19, 7-20, 8-21, 9-22, 10-23, 11-24, 12-25, and 13-26. 4. Conceptual Design of HIDiC In the present study, many sensitivity tests have been carried out to tune the design and operating variables. It is unlikely that a particular set of tunable data can provide the best product specifications with the usage of lowest amount of energy, and some compromise is generally required. Here, the design variables considered are the total number of stages (nT) and the product of the overall heat-transfer coefficient and the heatexchange area (UA), in addition to the operating variables (including CR and RR). Note that the total number of stages is kept unaltered. In the CDiC model, the termssnamely, CR and UAsdo not exist, because there are no compressor or internal heat exchanger connected between two stages. Keeping the input conditions the same for both distillation schemes, the variables of the HIDiC are systematically tuned to obtain the conditions that meet the product specifications. The energy consumption of the heat-integrated column (Qcons) is determined by adding the reboiler duty (QR) plus three times the compressor duty (Qcomp): Qcons ) QR + 3Qcomp

(1)

The factor of 3 for the compression duty is supposed to convert the compression work into the thermal energy required to produce an equivalent amount of electrical power. This is determined by taking into account the energy cost of electricity.13 4.1. Selection of Compression Ratio. Figure 4 illustrates how the compression ratio affects the product purity (xD) and overall energy consumption (Qcons) of the heat-integrated process. In this test, the values of UA and RR are chosen to be 5.2 kW/K per stage and 0.3, respectively. Other two parameter values (nT ) 26 and ∆P ) 0.3 kPa) are adopted from the conventional process simulator. It is evident that, as CR increases, the product purity increases. However, at the same time, the overall energy consumption also increases. To achieve the desired product purity in the distillate (xD ) 0.97), a


Figure 5. Effect of reflux ratio on (A) energy consumption and (B) distillate purity of the HIDiC column.

Figure 6. Effect of stage pressure drop on (A) energy consumption and (B) distillate purity of the HIDiC column.

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Figure 7. Effect of UA on (A) energy consumption and (B) distillate purity of the HIDiC column.

increase of ∆P. This happens because of the decrease in the flow rates inside the column. There is no significant change noticed in the energy consumption. 4.4. Heat Transfer (UA). The energy-integrated column with values of CR ) 2.6, nT ) 26, RR ) 0.3, and ∆P ) 0.3 kPa is chosen as a test process. The value of UA has been varied from 2.4 kW/K per stage to 5.6 kW/K per stage, and the corresponding composition and energy consumption profiles are presented in Figure 7. As the value of UA increases, the product composition goes up. At the same time, the reboiler duty decreases slightly, along with the small increase of compressor duty, because of the increased vaporization rate in the stripper. Overall, the energy consumption increases slightly with UA. To meet the product specification, a value of UA ) 5.2 kW/K per stage is chosen. Performing the above sensitivity tests for the heat-integrated distillation structure, the following quasi-optimal values have been obtained: CR ) 2.6, nT ) 26, RR ) 0.3, ∆P ) 0.3 kPa, and UA ) 5.2 kW/K per stage. 5. The Proposed Scheme: Intensified HIDiC

compression ratio of 2.6 has been selected. In fact, when the CR value becomes >2.6, the improvement of product composition is not so significant, in comparison to the rapid increase of energy consumption. 4.2. Reflux Ratio. This simulation investigates the behavior of the energy-efficient distillation column, in terms of product purity, and energy consumption, with respect to reflux ratio. The results are obtained in Figure 5 with the values of CR, nT, ∆P, and UA remaining unchanged. Clearly, as the reflux ratio increases, the product composition expectedly rises. However, the overall energy consumption constantly increases with increasing RR, because of the increasing heat load in the reboiler and condenser. We have selected a value of RR ) 0.3, which meets the product specification. Note that the minimum reflux ratio (0.2) of the HIDiC is determined by rule of thumb and a trial-and-error method. Interestingly, the selected RR value (0.3) is 1.5 times the minimum RR value. 4.3. Stage Pressure Drop. The influence of stage pressure drop on the distillate purity and energy consumption is displayed in Figure 6. This simulation experiment is performed considering a value of CR ) 2.6, along with fixed values of nT, RR, and UA. The distillate composition starts falling slowly with the

A new int-HIDiC structure is developed by introducing further energy integration in the HIDiC scheme presented above. In the proposed scheme, the latent heat of the overhead vapor from the rectifier is recovered through heat integration in a bottom reboiler. Actually, an additional thermal coupling is introduced between the overhead vapor of the rectifying section and the bottom liquid of the stripping section. By this enhanced heat integration, along with the reduction of steam consumption in the trim-reboiler, the use of a trim-condenser can also be avoided. The additional thermal coupling described above is made feasible by (i) using an additional compressor (Figure 8) or (ii) increasing the CR value in the existing compressor (Figure 9). The purpose is to make a temperature difference between the coupled streams. In this work, we call the former structure intHIDiC-1 and latter structure int-HIDiC-2. We might need an additional reboiler (denoted as R1) to start-up the proposed column, because of the thermal state of the feed (subcooled liquid), and to complete the heat balance and control the internal vapor rate at the bottom of the column. For the intensified structures, now we need to find the answers to the following two questions:

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Figure 8. Schematic of an int-HIDiC-1 column.

(i) What energy savings can be achieved through heat integration in the existing CDiC? (ii) What about the savings in terms of TAC for this substitution? 5.1. Energy Savings. Table 3 reports the cost of utilities. A comparison in terms of energy savings is conducted in Table 4 between the HIDiC and the int-HIDiCs, with reference to the CDiC scheme. Note that Table 4 compares the three HIDiCs, in terms of energy savings as well as TAC, and the bestperforming HIDiC (CR ) 2.6) is selected for comparison in the sequel. The overall energy consumptions by the int-HIDiC1, int-HIDiC-2, and HIDiC (CR ) 2.6) columns, and its conventional counterpart, are obtained as 601.39, 687.59, 1238.90, and 1546.72 kW, respectively. This represents an energy savings, which is defined as energy savings )

QCDiC - QHIDiC × 100 QCDiC

of 61.12% by the int-HIDiC-1, 55.54% by the int-HIDiC-2, and 19.90% by the HIDiC (CR ) 2.6). This proves successful application of the heat integration concept, in terms of energy savings to the example conventional distillation process. Next, we need to analyze the cost savings. 5.2. Cost Analysis. The energy integration in a distillation process may provide a significant energy savings, but at the cost of an increased capital investment. This work presents an economic comparison, in terms of total annual cost (TAC)

between the conventional and heat-integrated distillation schemes. We know that TAC ($/yr) ) OC +

CI θ

where OC is the operating cost, CI the capital investment, and θ the payback period. CI includes the cost of equipment (distillation column(s), heat exchangers, and compressor(s)) and OC includes the cost of utilities (heating steam, cooling water, and electricity) for a year that contains 8000 operating hours. The annual capital investment is calculated assuming a payback period of 3 years. The capital cost of the process is estimated using the correlations given in Table 5. Table 4 shows that savings of close to 11.45% and 7.15% in the total annual cost (TAC) are achieved by the int-HIDiC-1 and int-HIDiC-2 schemes, respectively. Interestingly, none of the HIDiC columns show any savings in TAC with a payback time of 3 years. The TAC of HIDiC (CR ) 2.6) is equal to that of CDiC for a payback time of 6.75 years. 6. Conclusions In this paper, a novel intensified energy integration technique is explored for the distillation column. Two intensified heatintegrated distillation column (int-HIDiC) schemes are developed by introducing further thermal coupling in the HIDiC configuration between the overhead vapor of the rectifier and


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Figure 9. Schematic of an int-HIDiC-2 column. Table 3. Details of Utilitiesa

a

item

value

steam cooling water electricity

$17/ton $0.06/ton $0.084/(kW h)

Data taken from ref 14.

technology, it is suggested to use an unequal number of stages for the rectifying and stripping columns. It is fairly true11 that the degree of heat integration and controllability are likely to have an inverse relationship. For the proposed energy-efficient scheme, all of these issues are not treated in this article, but they will be discussed elsewhere. Appendix

the bottom liquid of the stripper. In this way, along with the reduction of steam consumption in the reboiler, the use of a trim-condenser can also be avoided. To make the heat integration feasible, there is a need to increase the compression ratio (CR) for attaining a sufficient temperature difference between the two heat exchanging streams in a reboiler. For this purpose, in the int-HIDiC-1 scheme, an additional compressor is used for the overhead vapor from the rectifier. On the other hand, in the int-HIDiC-2 structure, a high CR value is developed in the existing compressor. Both of the proposed intensified columns provide significant energy savings and better economic figures than both the heat-integrated distillation column (HIDiC) and the conventional distillation column (CDiC). The application and performance of the proposed thermal integration technique are illustrated by a binary distillation example that separates an equimolar benzene/toluene mixture. A single example comparing different configurations does not indicate that the proposed method would work for all mixtures. Moreover, to improve flexibility of this intensified distillation

A typical nth tray is shown in Figure A1. The plate is fed with a liquid feed mixture. Side streams are withdrawn in both the liquid and vapor states. Numbering the stage with the bottom as stage 1 and the top as stage nt, the governing equations for the dynamic model of the nth (subscript n) tray of a HIDiC system can be stated as follows: nth Tray Total Mole Balance: m ˙ n ) Ln+1 + Vn-1 + Fn - (Ln + SLn ) - (Vn + SVn )

(A1) Component Mole Balance: m ˙ nx˙n ) Ln+1xn+1 + Vn-1yn-1 + Fnzn - (Ln + SLn )xn (Vn + SVn )yn (A2) Energy Balance:

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Table 4. Comparison of Estimated Capital (Main Equipment) and Operating (Utilities Per Year) Costs HIDiC

int-HIDiC-1

int-HIDiC-2

(CR ) 2.6)

(CR1 ) 2.6) (CR2 ) 1.15)

(CR ) 3.6)

CdiC

(CR ) 2.1)

duty area CW required cost of CW

1193.09 kW 107.97 m2 632028.64 ton/yr $37921.72/yr

679.12 kW 61.46 m2 359760.91 ton/yr $21585.65/yr

674.29 kW 61.02 m2 357201.31 ton/yr $21432.08/yr

duty of R1 area of R1 steam required duty of R2 area of R2 cost of steam

1546.72 kW 103.114 m2 20786.46 ton/yr 0 kW 0 353369.81

919.30 kW 61.287 m2 12354.57 ton/yr 0 kW 0 210027.75

848.15 kW 56.543 m2 11398.42 ton/yr 0 kW 0 193773.11

duty of Comp1 duty of Comp2 cost of electricity energy savings energy cost energy cost savings area of internal HE

0 kW 0 kW $0.00/yr

0 m2

98.51 kW 0 kW $73456.71/yr 21.46% $305070.11/yr 22.04% 10.625 m2

condenser reboilers column trays internal HEs compressors total capital cost

$261003.09 $253309.73 $412608.06 $42082.57 $0.00 $0.00 $969003.45

$180957.19 $180626.96 $412608.06 $42082.57 $578240.31 $219494.81 $1614009.90

payback period, θ TAC (θ ) 3 yrs)

$714292.68/yr

7.48 yr $843073.41/yr

item

(CR ) 3.1)

Condenser 670.24 kW 60.66 m2 355056.93 ton/yr $21303.42/yr

0 kW 0 m2 0 ton/yr $0.00/yr

0 kW 0 m2 0 ton/yr $0.00/yr

778.38 kW 51.892 m2 10460.77 ton/yr 0 kW 0 177833.09

180.19 kW 12.013 m2 2421.58 ton/yr 0 kWa 78.627 41166.79

44.18 kW 2.945 m2 593.76 ton/yr 0 kWa 94.585 10093.85

160.72 kW 0 kW $119844.38/yr 18.50% $318980.89/yr 18.48% 5.125 m2

130.25 kW 10.15 kW $104686.26/yr 61.12% $145853.05/yr 62.73% 6.5 m2

214.47 kW 0 kW $159924.27/yr 55.54% $170018.12/yr 56.55% 4.8 m2

$180119.29 $171412.90 $412608.06 $42082.57 $420134.40 $275974.72 $1502331.94

$179415.70 $162110.41 $412608.06 $42082.57 $359994.26 $327902.67 $1484113.67

$0 $275008.08 $412608.06 $42082.57 $420134.40 $310014.77 $1459847.88

$0 $264600.66 $412608.06 $42082.57 $344985.91 $415420.80 $1479698.00

6.75 yr $813101.88/yr

7.12 yr $813685.45/yr

2.00 yr $632469.01/yr

2.31 yr $663250.79/yr

Reboiler

Compressor

$391291.53/yr

130.25 kW 0 kW $97119.38/yr 19.90% $312324.57/yr 20.18% 6.5 m2 Capital Cost

a

Second reboiler (R2) receives heat through condensation of the overhead vapor.

Table 5. Cost-Estimating Formulasa and Parameter Valuesb

cost )

(

Column Shell M&S 101.9Dc1.066Lc0.802(cin + cmcp) 280

)

where Dc is the column diameter, Lc the column height, M&S ) 950, and the coefficients cin, cm, and cp have the following values: cin ) 2.18, cm ) 3.67, and cp ) 1.2 Column Tray M&S cost ) 4.7Dc1.55Lc(cs + ct + cm) 280

(

)

where the coefficients cs, ct, and cm have the following values: cs ) 1, ct ) 0, and cm ) 1.7 cost )

(

Heat Exchanger M&S 101.3A0.65[cin + cm(ct + cp)] 280

)

Figure A1. Quantities associated with a typical nth tray.

where the coefficients cin, cm, ct, and cp have the following values: cin ) 2.29, cm ) 3.75, ct ) 0.1, and cp ) 1.35 Compressor M&S cost ) 2047.24Qcomp0.82 280

(

a

)

Internal Heat Exchanger Stripping Section: Qn ) UA(T(nt/(2+n)) - Tn)

(A5a)

VSn )

Qn λn

(A5b)

LRn )

Qn λn

(A5c)

Data taken from ref 15. b Data taken from refs 16 and 17.

Rectifying Section: L V ˙ Ln ) Ln+1Hn+1 m ˙ nH + Vn-1Hn-1 + FnHFn - (Ln + SLn )HLn (Vn + SVn )HVn ( Qn (A3)

Compressor

Equilibrium (Species j): Ptyj ) γjP0j xj

(A4)

The following equation has been used to calculate the compressor work (Qcomp):


Qcomp )

[( )

VSµRTS PR µ - 1 PS

(µ-1)/µ

-1

]

(A6)

The value of the polytropic coefficient (µ) is taken to be 1.3. Compression of the vapor from the stripping section to the rectifying section is expressed as follows: TCO ) TS

( ) PR PS

(µ-1)/µ

(A7)

where TCO is the outlet temperature of the compressor. In the aforementioned model equations, F denotes the feeding rate (expressed in units of kmol/h), H the enthalpy (expressed in units of kJ/kmol), L the liquid flow rate (expressed in units of kmol/h), m the liquid holdup (expressed in units of kmol), P the pressure (expressed in units of kPa), Q the heat duty (expressed in units ofkW), R the universal gas constant (R ) 8.314 kJ/(kmol K)), S the side stream rate (expressed in units ofkmol/h), T the temperature (given in Kelvin), x the liquid composition (expressed as a mole fraction), y the vapor composition (also expressed as a mole fraction), V the vapor flow rate (expressed in units ofkmol/h), γ the activity coefficient, and λ the latent heat (expressed in units of kJ/kmol). The superscripts “L”, “V”, and “0” designate the liquid, vapor, and vapor pressure, respectively; the subscripts (and superscripts) R and S designate the rectifier and stripper, respectively. The dot symbol ( · ) that appears above some symbols is used to represent the time derivative of that symbol. The time derivative of the multiplication of two variables, for example, m and x, is denoted here by m ˙ x˙ )

d(mx) dt

Literature Cited (1) Schaller, M. Numerically Optimized Diabatic Distillation Columns, Ph.D. Thesis, Technische Universitat Chemnitz, Fakultat fur Naturwissenschaften, 2007. (2) Humphrey, J. L.; Seibert, A. F.; Koort, R. A. Separation Technologies AdVances and Priorities, Final Report for U.S. Department of Energy, Office of Industrial Technologist, Washington DC, 1991.

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(3) Meili, A. Heat Pumps for Distillation Columns. Chem. Eng. Progress 1990, 60–65. (4) Agrawal, R. Multicomponent Distillation Columns with Partitions and Multiple Reboilers and Condensers. Ind. Eng. Chem. Res. 2001, 40, 4258–4266. (5) Du¨nnebier, G.; Pantelides, C. C. Optimal Design of Thermally Coupled Distillation Columns. Ind. Eng. Chem. Res. 1999, 38, 162–176. (6) de Rijke, A. Development of a Concentric Internally Heat Integrated Distillation Column. Ph.D. Thesis, Technische Universiteit Delft, Delft, The Netherlands, 2007. (7) Nakaiwa, M.; Huang, K.; Endo, A.; Ohmori, T.; Akiya, T.; Takamatsu, T. Internally Heat-Integrated Distillation Columns: A Review. Trans. Inst. Chem. Eng. 2003, 81, 162–177. (8) Ho, T.-J.; Huang, C.-T.; Lin, J.-M.; Lee, L.-S. Dynamic Simulation for Internally Heat-Integrated Distillation Columns (HIDiC) for Propylenes Propane System. Comput. Chem. Eng. 2009, 33, 1187–1201. (9) Jana, A. K. Heat Integrated Distillation Operation. Appl. Energy 2010, 87, 1477–1494. (10) Fukushima, T.; Kano, M.; Hasebe, S. Dynamics and Control of Heat Integrated Distillation Column (HIDiC). J. Chem. Eng. Jpn. 2006, 39, 1096–1103. (11) Mali, S. V.; Jana, A. K. A Partially Heat Integrated Reactive Distillation: Feasibility and Analysis. Sep. Purif. Technol. 2009, 70, 136– 139. (12) Jana, A. K. Chemical Process Modelling and Computer Simulation; Prentice-Hall: New Delhi, 2008. (ISBN: 978-81-203-3196-9.) (13) Iwakabe, K.; Nakaiwa, M.; Huang, K.; Nakanishi, T.; Røsjorde, A.; Ohmori, T.; Endo, A.; Yamamoto, T. Energy Saving in Multicomponent Separation using an Internally Heat-Integrated Distillation Column (HIDiC). Appl. Therm. Eng. 2006, 26, 1362–1368. (14) Huang, K.; Shan, L.; Zhu, Q.; Qian, J. Adding Rectifying/Stripping Section Type Heat Integration to a Pressure-Swing Distillation (PSD) Process. Appl. Therm. Eng. 2008, 28, 923–932. (15) Douglas, J. M. Conceptual Design of Chemical Processes; McGrawHill: New York, 1988. (16) Lin, S.-W.; Yu, C.-C. Design and Control for Recycle Plants with Heat-Integrated Separators. Chem. Eng. Sci. 2004, 59, 53–70. (17) Olujic, Z.; Sun, L.; de Rijke, A.; Jansens, P. J. Conceptual Design of an Internally Heat Integrated Propylene-Propane Splitter. Energy 2006, 31, 3083–3096.

ReceiVed for reView April 22, 2010 ReVised manuscript receiVed June 24, 2010 Accepted August 17, 2010 IE100942P

A New Intensified Heat Integration in Distillation Column - American

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