Thermodynamic optimisation of distillation columns

Pinto, Filipe Soares; Zemp, Roger Josef; Jobson, Megan; Smith, Robin

doi:10.1016/j.ces.2011.03.022

Cited by 54 publications

(28 citation statements)

References 21 publications

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“…This applies to the heat pump too, except that the heat pump, which increases the cooling fluid temperature from the condenser, is probably simpler than diabatic column design. In paper [28] the addition of only one heat exchanger for the decrease in entropy production was considered, and it was concluded that an increase in the heat to be added to the column may be eliminated by adding several trays. The trends of the reduction of entropy production and the reduction of the exchanged heat with increased tray numbers can be observed based on the results in tab.…”

Section: Calculation Results and Discussionmentioning

confidence: 99%

Entropy production minimization in a multicomponent diabatic distillation column

2020

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This work presents a procedure for direct numerical minimization of entropy production in a diabatic tray column with heat exchanged on the trays as control variables, as opposed to previously used procedures with temperature on the trays as control variables. The procedure, which had previously been demonstrated on a binary mixture, was in this work applied to a multicomponent mixture, with minor modifications. The procedure comprised the complex optimization method and the Ishii-Otto method for solving the equations of a column model based on the iterative Newton-Raphson technique with partial linearization of the equations. The desired separation of the components was realized by the addition of a penalty function to the goal function, i.e. entropy production in the column. The required thermodynamic characteristics were calculated by the Soave equation of state. As an illustration, an industrial debutanizer with five components was used whose data, obtained by simulation, were compared with the optimization results of a diabatic column with the same desired separation and number of trays. After the diabatic column optimization procedure, the value of 91.91 J/Ks was obtained as the best result for entropy production. According to the best solution, entropy production in the diabatic column was 23.2% lower than in the adiabatic column. The heat to be removed from the column increased by 24.7%, while the heat to be added to the column increased by 28.8%.

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Section: Calculation Results and Discussionmentioning

confidence: 99%

Entropy production minimization in a multicomponent diabatic distillation column

2020

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“…For this mixture, the thermodynamic properties were calculated by the Peng–Robinson equation-of-state, as detailed in the Supporting Information, Appendix A. This means that enthalpies and k -values were calculated using the same thermodynamic package, being more appropriate for the exergy analyses . Since equilibrium and physical properties can be calculated using a unique thermodynamic package, the use of different thermodynamic packages may lead to numerical destruction of entropy, which violates the second law of thermodynamics.…”

Section: Methodsmentioning

confidence: 99%

“…Exergy balances, usually applied to whole equipment, were applied to each stage of the column, using the methodology proposed by Ognisty , and described in Zemp . This methodology was used in later works also for conventional columns, but considering nonideal and multicomponent mixtures, and in the optimization of columns by adding side heat exchangers . It was also adopted by Suphanit et al for the investigation of the DWC equipment.…”

Section: Methodsmentioning

confidence: 99%

Distillation Columns with Multiple Phase Divisions: How They Improve Thermodynamic Efficiency and Decrease Energy Consumption

Biasi

Romano

Zemp

et al. 2021

Ind. Eng. Chem. Res.

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Distillation efficiency can be improved by columns with multiple phase divisions, also known as parastillation (vapor division) and metastillation (liquid division). Although, previous studies demonstrate that these configurations improve separation efficiency, little is known about the mechanisms that cause this improvement. These mechanisms are elucidated through exergetic and driving force analyses. Methanol-ethanol and multicomponent hydrated bioethanol purifications were investigated. Thermodynamic efficiency and exergy losses are improved when the number of phase divisions is increased. In methanol-ethanol distillation, the increase of the number of phase divisions from one to eight decreases both the operational costs and CO 2 emissions by 34% and increases thermodynamic efficiency by 23%. Considering a more feasible number of phase divisions, from the construction point of view, four divisions improve operational costs by 31%, over one division. In the production of hydrated bioethanol, four-vapor divisions lead to a reduction in energy consumption by 18% when compared with conventional distillation. This study shows that it is possible to reduce operating costs to a value close to the theoretical minimum, without a significant increase in capital costs. This observation contrasts with the conventional process, in which the reduction in operating costs necessarily leads to higher distillation columns and capital costs.

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“…The exergy distribution model of each stage is shown in Figure . For stages containing reboilers, condensers, and side reboilers, the exergy loss is calculated as

{Ex}_{loss} = Q ((), 1 - \frac{T_{UTY o}}{T_{UTY i}}) + {Ex}_{in} - {Ex}_{out}

…”

Section: Study Conditions and Methodsmentioning

confidence: 99%

The improvement and analysis of the high‐pressure propane recovery process

Jiang

Zhang

Jing

et al. 2018

Asia-Pacific J Chem Eng

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The recovery of propane from high‐pressure natural gas is an effective approach to increasing the economic benefits of the gas field. Currently, the high‐pressure absorber (HPA) process is the most common process available for recovering high‐pressure natural gas liquid. We have proposed two improved processes based on the HPA process for propane recovery from high‐pressure natural gas: revised HPA and HPA recycle liquid (HPARL) processes. Through the optimization algorithm, the three processes were optimized with the lowest unit energy consumption as the objective. The optimization results show that the HPARL process has a substantial energy‐saving advantage when the feed pressure is sufficiently high under lean gas conditions, whereas the HPARL process requires greater cooling capacity than the HPA and revised HPA processes under rich gas conditions to ensure recovery. The exergy analysis of the processes under the optimized conditions shows that the main exergy loss in the three processes originates from the deethanizer and that the exergy loss difference caused by the deethanizer in each process is derived from the first stage and the eighth stage. Because of the extensive exergy loss at the first stage of HPARL, this process has the highest deethanizer exergy loss under all conditions. The exergy efficiency difference among the three processes is very small under different conditions.

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Thermodynamic optimisation of distillation columns

Cited by 54 publications

References 21 publications

Entropy production minimization in a multicomponent diabatic distillation column

Entropy production minimization in a multicomponent diabatic distillation column

Distillation Columns with Multiple Phase Divisions: How They Improve Thermodynamic Efficiency and Decrease Energy Consumption

The improvement and analysis of the high‐pressure propane recovery process

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