Energy saving of side-column DWCs for quaternary separation

2019

Biotechnol Biofuels

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Background Volatile fatty acids (VFAs) are produced by fermentation of various bio-sources and human wastes at minimal cost; sometimes, even sources having a prepaid processing fee were used. However, low concentrations of VFAs in water have prevented their commercial production, even with modern separation technologies, due to the high operating costs. We have applied newly developed solvents, selected by chemical structure similarity, to the separation of five different VFAs. Results Since most of the water was separated by extraction using hexyl acetate and nonyl acetate, the utilities necessary for solvent recovery and product purification were a fraction of those required by the existing VFAs’ separation processes. The solvents separated almost all the water in the feed at the extraction stage, consuming no energy. The energy use in this study is only 34% of the lowest case use among various processes of either distillation-only or combined extraction–distillation. Conclusions The performance evaluation of the proposed VFAs separation process showed that product recovery was 99% and acid purity was 99.5% with eco-scores of 70% lower than those of the current processes. Electronic supplementary material The online version of this article (10.1186/s13068-019-1433-8) contains supplementary material, which is available to authorized users.

Section: Resultsmentioning

confidence: 99%

Eco-efficient recovery of bio-based volatile C2–6 fatty acids

Woo

2019

Biotechnol Biofuels

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“…The investment cost was computed using the equations given in Refs. [26][27][28] with Marshall & Swift cost index of 1593.7 in 2017. The payout time of the investment was three years, and the annual number of operating days was 300.…”

Section: Process Designmentioning

confidence: 99%

Molecular Simulation‐Assisted Solvent Selection for Separation of 1,2,4‐Trimethylbenzene

Cho

2018

Chem Eng & Technol

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Extractive distillation is an alternative for processes where normal distillation is difficult, such as separation of close‐boiling mixtures, but solvent selection for distillation is laborious, and its selection pool is narrow. An innovative selection process using molecular simulation is proposed, and the performance of the selected solvent, 1,2,4‐trichlorobenzene, for the separation of 1,2,4‐trimethylbenzene from a C9 mixture is reviewed. The proposed process requires less investment and leads to lower operating expenses than the conventional two‐column process. The computed vapor‐liquid equilibrium determined from the molecular simulation is close to the HYSYS estimation in two ternary systems.

“…The total tray number in the columns is similarly matched to the conventional CDU, only without the strippers. The general structure of the two‐column setup is similar to a side‐stripper DWC , however, this structure cannot be built as a DWC due to the unbalanced interlinking streams between the two columns. The column operating pressure was set 0.13 MPa lower than the conventional column for increased efficiency.…”

Section: Process Designmentioning

confidence: 99%

An Energy‐Efficient Crude Distillation Unit with a Prefractionator

2017

Chem Eng & Technol

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An energy‐efficient crude distillation unit (CDU) was proposed, and its performance was evaluated and compared with that of a conventional CDU. The problem of the large energy demand associated with the single‐column operation of a conventional CDU was solved with a two‐column operation – a prefactionator and a main column – in the proposed CDU. The two‐column operation reduces feed‐tray mixing, and thus raises the thermodynamic efficiency of the CDU. The proposed unit has reduced heating and cooling duty compared with that of the conventional unit. The proposed unit also has fewer investment and utility costs. Vapor and liquid flow connections between the two columns are readily available by adjusting the difference in column operating pressure.