A Process Synthesis and Intensification Framework

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

All comments have been revised. I suggest that it be published on Encyclopedia.

 

In addition, we found that the literature quoted by the author was not completely applicable.

Be applicable：1, 2, 6, 27, 29, 30.

Not applicable: The second and third literatures are the reactive processing process of carbonate dilate. It is recommended to keep one; The literature of the 26 is to propose a distillation process structure of a ternary mixture with a common boiling object, not the decanter; The author quoted many of his own papers in line 28 of the fifth page, which cannot prove the correctness of the author's theory. The author should cite more documents of other authors to prove it, so the author of the 28th document can change it; The 31st literature is mainly about simulated annealing algorithms rather than membrane rectification.

Author Response

A1: Thank you very much for your valuable comments. In reviewing the non-applicable citations, in this case [2] and [3] both effectively talk about the production of diphenyl carbonate via reactive distillation, but the second citation is complementary to the first, since citation [2] talks about a reduction in energy costs of 22% with respect to the conventional sequence by using heat integration, while citation [3] talks about a 47% reduction in energy with respect to the conventional sequence with heat integration and adding thermal coupling to the scheme. The first citation talks about an intensification of the process and the second talks about a further intensification of the process. To avoid any confusion, we have deleted reference [2] in the revised version, while [3] was kept in the revised version.

Reference [27] in the revised version refers to the separation of the mixture of acetone, chloroform and benzene where the result is a direct distillation sequence as an optimal scheme without the use of decanters and without prior knowledge of the structure of the process. We made a mistake for reference [26] in the original version. The problem is already fixed, and now the correct reference is [26] in the revised version.

As pointed by the reviewer, references [27-31] in the revised version           are the authors' own works for different scenarios and applications. Our proposed Process Synthesis and Intensification (PS+I) framework is a further extension of the IDEAS framework [22,23,25] with the low aggregation superstructure. Because this extension is a very recent technique, the reported literature on its application are our specific case studies, hoping that with this work the literature will be expanded in its application for other authors.

Reference [32] discusses the optimization via the modified simulated annealing algorithm of an azeotropic distillation process of the water/ethanol mixture with benzene in a scheme obtained from the solution of a low aggregation superstructure. Although this work focuses more on post-optimization, it contributes significantly to how cost and energy reductions are achieved in the PS+I framework once the optimal scheme is obtained to move on to the optimal design.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

The authors reported a mathematical optimization-based approach for synthesize distillation process. This method is based on a low aggregation superstructure. The mixed integer nonlinear programming (MINLP) problem was solved by relaxing material and energy balance. This method was tested with fractionation distillation of Benzene, Toluene, and o-Xylene. This method was applied to dehydration of ethanol, either by heterogeneous azeotropic distillation or by integrating a membrane separation module. The results shows that the proposed approach is effective for designing different types of distillation-based processes. A few things to clarify:

•The objective function should be explicitly described. •“Post-optimization shows a better balance between energy consumption and equipment cost”, are there any data to support this comment? •“Counter-intuitive distillation structure”, what would be the normal structure?   Comments on the Quality of English Language

Line 242 “Petluk coumn” should be Petlyuk

Author Response

A2: Thank you very much for your comments. Information about the objective function in post-optimization, and complementary information for the comment “post-optimization shows a better balance between energy consumption and equipment cost” has been added to the document. The text explanation has been added from lines 250to 258. Table 3 in the revised version compares the difference before and after post-optimization. The equipment cost reduced almost 0.6 M$/year, but the energy consumption only increased 3 kW. It means the post-optimization can greatly reduce the equipment cost without affecting the energy consumption cost, because the latter one is already optimized at the synthesis step.

 Regarding the comment “Counter-intuitive distillation structure” it refers to the fact that non-conventional schemes can be obtained, In lines 132,133in the revised version, we have stated “For example, a combination of conventional distillation columns will never result into a Petlyuk column”

Low aggregation superstructure can obtain feasible non-conventional schemes that can improve the economy and energy of the process addressed. Therefore, in this document different mixtures that have already been resolved by the literature are taken, but here novel alternatives are proposed.

Finally, the following text was added at the end of Section 2.2,  “ The solutions in Figures 8 and 9 are counter-intuitive because, typically, in conventional processes, the top vapor in the first column goes to the decanter, and it never is recycled to the same column. The presented solutions are against common practice and experience, yet they have much lower cost and energy consumption than the conventional processes presented by Richardson et al. [33] consisting of three conventional columns and a decanter. The heat duty of the conventional process was 5.985 MW, which is almost twice the heat duty of the solution in Figure 9.”

A1: Thank you. We have fixed this typo.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

The article presents a good review of the previous development by the authors in the field of Process Synthesis and Intensification. A wider vision of the state of the art should be included in the Introduction, including more references to previous works (both seminal and recent reviews) on the topics of Process Synthesis and Process Intensification.

In general, the article is well written, well organized and provides a suitable and updated information about the topic. With the improvement described previously, the article should be ready for publication.

Author Response

A: Thank you for your comments. Indeed, there are many works on process synthesis and much many more works on process intensification, but there are few works tackling both issues in an integrated framework. The works from the presented research groups show the state of the art of low aggregation superstructures.

Round 2

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

All comments have been revised. I suggest that it be published on Encyclopedia.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors Line 49, the words should be: membrane crystallization, membrane distillation

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Explanations from the authors are understandable. The article is acceptable.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript “Process Synthesis and Intensification (PS+I) framework” used a low aggregation superstructure to solve the synthesis problem, and its solution was interpreted and transformed into a strengthening process of task integration. Based on the balance between operating cost and equipment cost, the process was optimized later, and finally a novel, counter-intuitive, low-cost and low-energy strengthening process was proposed. The manuscript can be published in “Encyclopedia” after a major revision. The concerns which should be considered by the authors are as follows:

1. In the introduction, the authors should clarify what is novel about the paper. The author should describe in detail the innovations of this work.  In contrast to other similar manuscripts, the authors should specify the valid contribution of the paper in detail in the introduction.

2. The color and layout of Figure 2. Low aggregation superstructure representation is unreasonable, and it looks cluttered and unclear. The authors should re-arrange the layout.

3. In the " 2.1. Separation of a ternary mixture", the description of the process is too simple, the authors should re-describe the process with reference to the following literature. Ma et al. analyzed extractive distillation from the aspects of phase equilibrium, solvent selection, process design, energy saving and dynamic control, and highlighted the improvement of these advanced technologies in recent years (Chinese Journal of Chemical Engineering, 2019, 27, 7, 1510-1522); Zhao et al. investigated two thermally-coupled ternary extraction distillation processes to separate tetrahydrofuran/ethanol/water ternary azeotropes, taking into account thermodynamic efficiency and CO₂ emission indices, to assess the energy efficiency and environmental impact of alternative ternary extraction distillation processes (Energy, 2018, 148: 296-308).

4. According to the "Author's Guide", the authors should unify the reference format and make it easy for readers to read.

5. It is recommended that authors create a special section for the design basis, detailing feed conditions and design parameters.

6. In the introduction, the authors mentioned that “Previous works used superstructure representations comprising several unit operations such as distillation columns, heat exchangers, decanters, or membranes.” Please explain what the superstructure is.

7. Give original reference for equations 1 and 2. It is important to cite and credit the original papers for the equations.

8. In the manuscript, formulas, figures and figure titles should be centered in the manuscript.

9. Please discuss the limitations of the process synthesis and intensification (PS+I) framework.

10. In the introduction, there is not enough literature on distillation. Please the authors add related research literature. Such as, Guo et al. compared ILs and organic solvent processes by considering energy and economic aspects(Separation and Purification Technology, 2021, 276, 119338); Ma et al. analyzed the economy, environmental protection and sustainability of the three separation processes of benzene/n-propanol/water(Process Safety and Environmental Protection, 2021, 148, 462–472); Geng et al. adopted the exergy, economic and environmental analysis to evaluate the economic and environmental effect of the pressure-swing reactive distillation process(Process Safety and Environmental Protection, 2022, 158, 525–536); Sina et al. presented technical and economical evaluation of a multi effect distillation system which utilizes the vapor produced from waste heat of exhaust flue gases(Desalination, 2019, 460, 64–80); Du et al. studied the economic optimization and analysis of the production process of ethyl propionate by reactive distillation(Chemical Engineering & Processing: Process Intensification, 2022, 172, 108779); Modla et al. studied the feasibility of separation of ternary mixtures by pressure swing batch distillation(Chemical Engineering Science, 2010, 65, 870–881); Salman et al. studied the residual curves of ethanol+ethyl propionate+glycerol under different pressures(Separation and Purification Technology, 2023, 311, 123361); Zhang et al. studied the special azeotropic behaviors at different pressures of Benzene/isobutanol(Separation and Purification Technology, 2022, 296 121381).

Comments on the Quality of English Language

Minor editing of English language required

Author Response

Please see the authors' reply as attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript submitted for review is about an important topic for plant/process design. Considering the Journal's goal, I have some concerns about the structure of the text. 

In Introduction section, a literature review about the subject is given. However, it should be more descriptive and critical about the different approaches used for process synthesis and intensification. A clear comparison is important to highlight the technology evolution and to stant out new developments. 

Authors explore the method they developed for process synthesis and intensification. However, the examples cited in the text are not descriptive enough to allow the readers to have a clear understanding of the topic, that is, process synthesis and intensification.

Please, check:

Table 1. Figure numbers should be 8 and 9.

Line 270. It should be Table 2 instead of 1.

Based on the Encyclopedia editiorial goals, I believe this manuscript needs to be restructured to meet the requirements for publication.

Author Response

Please see the authors' reply as attached.

Author Response File: Author Response.pdf