Comparison of alternative distillation processes for the maximum-boiling ethylenediamine dehydration system

Yu, Hao; Ye, Qing; Xu, Hòng; Dai, Xin; Suo, Xiaomeng; Li, Rui

doi:10.1016/j.cep.2015.09.008

Cited by 19 publications

(20 citation statements)

References 22 publications

(25 reference statements)

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“…Luyben adopts a slope criterion to devise a temperature-control strategy for a pressure-swing distillation system and an extractive distillation system, and the dynamic responses reveal that significant steady-state offsets present in product purities when the two distillation systems face the feed disturbances. A similar situation can be found in many analogous studies. − Alternatively, some studies , use an open-loop sensitivity test to find the temperature control stage which shows large temperature deviation to the variation of manipulated variable, but this open-loop method did not guarantee the control structure would effectively reject feed disturbances either.…”

Section: Introductionmentioning

confidence: 71%

Control Study to Enhance the Controllability of Heterogeneous Extractive Distillation: Cyclohexane/Cyclohexene Separation

Chien

2019

Ind. Eng. Chem. Res.

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Control strategy is crucial for the smooth operation of distillation systems, especially when the design flowsheet is complicated. In this work, a control strategy is proposed for a recently published heterogeneous extractive distillation system separating cyclohexane and cyclohexene. During the investigation of control strategy, a closed-loop sensitivity test is adopted to analyze the controllability of this distillation system, and the results show that some modifications for the steady-state design must be made to facilitate the implementation of suitable control structure. After redesigning the separation process, closed-loop sensitivity test is again performed for the purpose of successfully setting up a single-temperature control scheme for two distillation columns and also determine which variable/ratio is to be fixed. The results of open-loop and closed-loop sensitivity tests are taken into consideration together for the sake of selecting the appropriate stage for temperature control. In addition, a closed-loop sensitivity test is also used for the preinvestigation of throughput disturbance rejection to devise feedforward control action. According to the closed-loop dynamic responses, the proposed control strategy enables the heterogeneous extractive distillation system to properly reject ±20% feed composition disturbances and ±10% throughput changes.

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Section: Introductionmentioning

confidence: 71%

Control Study to Enhance the Controllability of Heterogeneous Extractive Distillation: Cyclohexane/Cyclohexene Separation

Chien

2019

Ind. Eng. Chem. Res.

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“…Note that the number of maximum azeotrope separation case studies investigated in the literature is limited to seven as far as we know, the last one in 2015 (Yu et al, 2015) (see Supplementary material).…”

Section: For Details)mentioning

confidence: 99%

Review of extractive distillation. Process design, operation, optimization and control

Gerbaud

Rodríguez-Donis

Hégely

et al. 2019

Chemical Engineering Research and Design

190

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Operation and control Extractive distillation processes enable the separation of non-ideal mixtures, including minimum or maximum boiling azeotropes and low relative volatility mixtures. Unlike azeotropic distillation, the entrainer fed at another location than the main mixture induces an extractive section within the column. A general feasibility criterion shows that intermediate and light entrainers and heterogeneous entrainers are suitable along common heavy entrainers. Entrainer selection rules rely upon selectivity ratios and residue curve map (rcm) topology including univolatility curves. For each type of entrainer, we define extractive separation classes that summarize feasibility regions, achievable products and entrainer-feed flow rate ratio limits. Case studies are listed as Supplementary materials. Depending on the separation class, a direct or an indirect split column configuration will allow to obtain a distillate product or a bottom product, which is usually a saddle point of rcm. Batch and continuous process operations differ mainly by the feasible ranges for the entrainer-feed flow rate ratio and reflux ratio. The batch process is feasible under total reflux and can orient the still path by changing the reflux policy. Optimisation of the extractive process must systematically consider the extractive column along with the entrainer regeneration column that requires energy and may limit the product purity in the extractive column through recycle. For the sake of reducing the energy cost and the total cost, pressure change can be beneficial as it affects volatility, or new process structures can be devised, namely heat integrated extractive distillation, extractive divided wall column or processes with preconcentrator.

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“…(6) The 7th tray temperature of the first column is controlled by adjusting the reboiler duty (Q R1 ), while the 4th tray temperature of the second stripping column is controlled by Q R2 (reverse acting). (7) The temperature of the decanter is controlled by adjusting the heat duty of the condenser (reverse acting). (8) 1 min of dead time is inserted into all temperature control loops to fit the practical operation.…”

Section: Basic Control Structure (Cs1)mentioning

confidence: 99%

“…Qin et al designed an extractive distillation setup using sulfolane as entrainer to separate benzene/cyclohexane. Yu et al explored the separation of a maximum‐boiling ethylenediamine dehydration system via extractive distillation and heterogeneous azeotropic distillation. 1,4‐Butanediol and n ‐propyl acetate were selected as suitable heavy/light entrainers for each distillation process.…”

Section: Introductionmentioning

confidence: 99%

Design and Control of Heterogeneous Azeotropic Distillation for Separating 2‐Methylpyridine/Water

Chen

Liu

et al. 2018

Chem Eng & Technol

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In industrial processes, 2‐methylpyridine/water mixtures can be separated via the conventional heterogeneous azeotropic distillation (HAD) using benzene as entrainer. 2‐Methylpyridine and water can form a heterogeneous azeotrope by themselves, based on which an improved HAD process is proposed. This allows for reducing the total operating cost and total annual cost (TAC) by more than one‐tenth compared with the conventional HAD process. Two different control structures were established for the enhanced HAD process. The results indicate that applying the feedforward ratio controllers to the control structure can handle the feed disturbances and maintain product purities with smaller transient deviations and shorter settling times.

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Comparison of alternative distillation processes for the maximum-boiling ethylenediamine dehydration system

Cited by 19 publications

References 22 publications

Control Study to Enhance the Controllability of Heterogeneous Extractive Distillation: Cyclohexane/Cyclohexene Separation

Control Study to Enhance the Controllability of Heterogeneous Extractive Distillation: Cyclohexane/Cyclohexene Separation

Review of extractive distillation. Process design, operation, optimization and control

Design and Control of Heterogeneous Azeotropic Distillation for Separating 2‐Methylpyridine/Water

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