Energy-saving thermally coupled ternary extractive distillation process by combining with mixed entrainer for separating ternary mixture containing bioethanol

Guang

Cui

et al. 2019

BACKGROUND The ternary mixture of tetrahydrofuran (THF), ethanol and water contains multiple azeotropes with the sensitivity to pressure variation. The pressure‐swing distillation (PSD) is a promising method to achieve the system's separation objective since it avoids many potential problems caused by adding a third component. RESULT A variety of separation sequences were synthesized on the ternary diagram, including the sequences of WLEMTH, WLTH EM, THEMWL, THWLEM, EMTHWL and EMWLTH. The optimal design parameters of these sequences were obtained based on the minimum total annual cost (TAC) by using the sequential iterative global optimization algorithm. Furthermore, six kinds of heat integration that improve energy efficiency were implemented for the optimal alternative of EMTHWL. CONCLUSION The results show that the EMTHWL configuration has the lowest TAC, saving 37.84% of the economic cost compared to the THEMWL which has the highest TAC. The partial heat integration among three columns can achieve almost the same reductions in energy requirements and carbon dioxide emissions (44.9%) as the full heat integration among three columns (45.4%). In addition, it is predictable that the partially heat‐integrated alternative compared to other fully heat‐integrated schemes has less undesirable side effects in the aspect of dynamic control. © 2019 Society of Chemical Industry

Section: Sequence Synthesismentioning

confidence: 99%

Section: Multiple Heat Intergationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Separation of a ternary mixture with multiple azeotropes via pressure‐swing distillation

Guang

Cui

et al. 2019

“…CO 2 emission is also an important indicator for evaluating the environmental impact of the optimal design. It can be calculated for a given amount of burnt fuel through the expressions presented in the literature . A detailed calculation procedure is shown as follows:

[{CO}_{2}] emission = (\frac{{italicAmt}_{Fuel}}{NHV}) \times (\frac{C %}{100}) α

where α is the molar mass ratio of CO 2 and C, 3.67; NHV is the net heating value and C % is the carbon content of a specific fuel.…”

Section: Design Basismentioning

confidence: 99%

Hybrid reactive distillation using polyoctylmethylsiloxane membrane for isopentyl acetate production from mixed PVA by products

Guang

et al. 2018

Self Cite

BACKGROUND The transesterification of methyl acetate and isoamyl alcohol catalyzed by ionic liquids is a new environment‐friendly method for isopentyl acetate (iso‐AmAc) production, and also appropriate for the recovery of polyvinyl alcohol (PVA) byproducts. Therefore, it is of great significance for iso‐AmAc production from PVA byproducts to explore alternative processes with the goal of improving the conversion of the chemical equilibrium reaction and energy efficiency, including reactive distillation (RD), dividing‐wall reactive distillation (RDWC) and pervaporation (PV)‐based hybrid reactive distillation. RESULT This article proposed four novel reactive hybrid processes with feedstock of mixed PVA byproducts and made a comparison with two conventional processes of RD and RDWC in terms of the minimum total annual cost (TAC) and CO2 emissions. The results revealed that the RDWC‐PV can give a 35.61% saving in TAC and a 40.27% reduction in CO2 emissions compared with the RD, and the other three RD‐PV hybrid processes have less CO2 emissions and equivalent TAC compared with the RDWC. CONCLUSION In summary, all hybrid processes proposed were more energy‐saving and economical than the conventional RD, especially the RDWC‐PV, due to synergistic advantages of various process intensification methods. © 2018 Society of Chemical Industry

“…Extractive distillation is widely applied to separate azeotropes because of its advantages such as strong separation ability, simple operation and flexible selection of entrainer . Selecting entrainer is a key factor for extractive distillation . In the reports on the separation of benzene–methanol azeptrope by traditional organic entrainer, the azeotropic mixture can be completely separated by aniline, propyl butyrate, anisole, etc …”

Section: Introductionmentioning

confidence: 99%

Evaluation of ionic liquid separation ability for the benzene–methanol mixture by extractive distillation

Feng

et al. 2019

BACKGROUND Benzene–methanol azeotrope can be formed at atmospheric pressure. Extractive distillation is widely used in the separation of azeotrope. The key factor for extractive distillation is the selection of entrainer. The minimal total annual cost of extractive distillation process can be used as objective function to evaluate the separation performance of ionic liquid entrainer. Intermolecular interaction energy can be used to analyze separation mechanisms. RESULT An Aspen Plus software database belonging to the three ionic liquids 1‐hexyl‐3‐methylimidazolium acetate, 1‐octyl‐3‐methylimidazolium acetate and 1‐decyl‐3‐methylimidazolium acetate was established. The minimal total annual costs of three extractive distillation processes for the separation of benzene–methanol mixture with different ionic liquids were obtained by sequential iterative method. The feed rate of entrainer was also obtained under the optimized conditions. Among the three extractive distillation processes with different ionic liquid, the total annual cost and the entrainer feed rate of the extractive distillation process with 1‐hexyl‐3‐methylimidazolium acetate as entrainer are the smallest. The intermolecular interaction energies in the ternary system of benzene–methanol–ionic liquid were obtained using the Gaussian 09 software package based on the density functional theory. The separation mechanisms and the extractive distillation process of benzene–methanol azeotrope with ionic liquid as entrainer was interpreted by the intermolecular interaction energy. CONCLUSION The results show that the separation ability of 1‐hexyl‐3‐methylimidazolium acetate is higher than that of 1‐octyl‐3‐methylimidazolium acetate or 1‐decyl‐3‐methylimidazolium acetate. Intermolecular interaction energy analysis can be used in the screening and design of ionic liquid entrainer. © 2019 Society of Chemical Industry