Dividing-Wall Column Design: Analysis of Methodologies Tailored to Process Simulators
, Nancy Medina-Herrera 3, Arturo Jiménez-Gutiérrez 4, José A. Loredo-Medrano 1 and Salvador Tututi-Avila 1,*
Round 1
Reviewer 1 Report
In this paper, the authors studied several design methodologies reported in the literature for DWCs, i.e., Triantafyllou and Smith (T&S), minimum vapor (Vmin), and Sotudeh and Shahraki (S&S) methods, along with their implementation on process simulators. In addition, a modification to the S&S methodology is proposed. The paper was well written and carefully prepared which contains an interesting result in the research area. However, there are some issues should be addressed before it can be recommended for publication. Some suggestions for the revision of the work are indicated below.
- The abbreviation list should be included for a better understanding of readers.
- Explain the reason to include 5 case studies
- Explain more details about how to find out the optimal design of DWCs in this study
- Was the product purity of 99 mol% specified for all products? How about the product recovery?
- Please explain Figure 9 in more detail. Why was the economic performance far different between these case studies with the Vmin and S&S methods?
- The originality of the paper needs to be further clarified and emphasize in the revised manuscript.
Author Response
We want to thank the reviewer for the thoughtful and valuable comments, which have helped us improve the manuscript. Each comment has been carefully considered and has been addressed in the revised manuscript. Below are our responses to each of the points raised by the reviewer.
Reviewer’s comment:
In this paper, the authors studied several design methodologies reported in the literature for DWCs, i.e., Triantafyllou and Smith (T&S), minimum vapor (Vmin), and Sotudeh and Shahraki (S&S) methods, along with their implementation on process simulators. In addition, a modification to the S&S methodology is proposed. The paper was well written and carefully prepared, which contains an interesting result in the research area. However, there are some issues should be addressed before it can be recommended for publication. Some suggestions for the revision of the work are indicated below.
Reviewer’s comment:
1. The abbreviation list should be included for a better understanding of readers.
Response: An abbreviation list has been included, as suggested by the reviewer.
Reviewer’s comment:
2. Explain the reason to include 5 case studies.
Response: Section 3 of page 13 has been expanded to explain that the five case studies cover a range of different separation systems characterized by the ease of separation index.
Reviewer’s comment:
3. Explain more details about how to find out the optimal design of DWCs in this study.
Response: Section 2.5 has been expanded to include details of the optimization method we used to obtain the optimal design, including the optimization model.
Reviewer’s comment:
4. Was the product purity of 99 mol% specified for all products? How about the product recovery?
Response: That is correct, a product purity of 99 mol% was specified. Although recoveries were not used as a product specification, they were for all case studies higher than 0.99 for the light and heavy products (A and C) and higher than 0.97 for the intermediate product (B). The first paragraph of section 4 has been expanded to highlight this point.
Reviewer’s comment:
5. Please explain Figure 9 in more detail. Why was the economic performance far different between these case studies with the Vmin and S&S methods?
Response: We thank the reviewer for this important observation. The discussion of Figure 9 has been expanded in section 4.4. Although both the Vmin and the S&S methodologies are based on the Vmin diagram to obtain the internal flow rates of the column, their final designs have significant differences in their economic performance. Such differences can be attributed to the form in which structural arrangement is establish for each method and the mixture properties, assessed through their ESI values.
Reviewer’s comment:
6. The originality of the paper needs to be further clarified and emphasize in the revised manuscript.
Response: The paper novelty has been highlighted in the introduction section (please see lines 146-151).
Author Response File: 
Author Response.pdf
Reviewer 2 Report
1) Abbreviation list must be added in the revised version
2) Figures should be unified regarding the size, font and scale.
3) A new part must be open before the conclusion and discuss future perspectives， plus discussing about advantages and disadvantages。
4) Please describe why the error bars and tolerances were not mentioned and your expectation for reproducibility of the presented data in different cases rather than the five discussed.
Author Response
We want to thank the reviewer for the thoughtful and valuable comments, which have helped us improve the manuscript. Each comment has been carefully considered and has been addressed in the revised manuscript. Below are our responses to each of the points raised by the reviewer.
Reviewer’s comment:
1. Abbreviation list must be added in the revised version
Response: An abbreviation list has been included, as suggested by the reviewer.
Reviewer’s comment:
2. Figures should be unified regarding the size, font, and scale.
Response: All figures have been adjusted, as suggested.
Reviewer’s comment:
3. A new part must be open before the conclusion and discuss future perspectives, plus discussing advantages and disadvantages.
Response: We appreciate this suggestion and have made appropriate changes. A new section (4.6) has been added to discuss the advantages and drawbacks of the design methods, as well as our view on the future perspectives.
Reviewer’s comment:
4. Please describe why the error bars and tolerances were not mentioned and your expectation for reproducibility of the presented data in different cases rather than the five discussed.
Response: Section 4.4 has been expanded to clarify the results shown in Figure 9. Additional work must be done to test the trends given by the behavior of the design methods tested in this work as a function of the ESI values of other mixtures. We can also say that the reproducibility of the current design methods is tied to non-azeotropic mixtures.
Author Response File: Author Response.pdf
Reviewer 3 Report
This was a well organized and written submission. I have only minor suggestions.
- The minimum vapor is referred to as Vmin and Vmin. I think you should be consistent.
- Vmin reported the most, Vmin Fig 4, p8 line 295, p11 line401, p18 line595
- Same comment for flow rate, sometimes written as flowrate( pg 3 line 100)
- Reference 15 may be missing the page numbers for the citation
- Page 13 line 450 states that the pressure was set so that water could be used as a coolant, about what temperature range of water would be needed?
- the one suggestion that I would be to include a table that quickly summarizes the results for the 5 case studies with advantages and disadvantages
Author Response
We want to thank the reviewer for the thoughtful and valuable comments, which have helped us improve the manuscript. Each comment has been carefully considered and has been addressed in the revised manuscript. Below are our responses to each of the points raised by the reviewer.
Reviewer’s comment:
This was a well-organized and written submission. I have only minor suggestions.
- The minimum vapor is referred to as Vmin and Vmin. I think you should be consistent.
- Vmin reported the most, Vmin Fig 4, p8 line 295, p11 line401, p18 line595
Response: We thank the reviewer for this observation. The paper has been revised for a consistent use of this variable.
Reviewer’s comment:
- Same comment for flow rate, sometimes written as flowrate (pg 3 line 100)
Response: The paper has also been revised to address this point.
Reviewer’s comment:
- Reference 15 may be missing the page numbers for the citation.
Response: Reference 15 has been revised to include those missing page numbers.
Reviewer’s comment:
- Page 13, line 450 states that the pressure was set so that water could be used as a coolant. About what temperature range of water would be needed?
Response: Cooling water is assumed to be available at 25°C. If we assume an increase of the cooling water temperature of 4ºC and a temperature difference of 10ºC, the distillate temperature is set to 49ºC. This detail has now been explained in the revised manuscript. Thank you for the observation.
Reviewer’s comment:
The one suggestion that I would be to include a table that quickly summarizes the results for the 5 case studies with advantages and disadvantages.
Response: Thank you for the suggestion. A table with the advantages and drawbacks of each methodology has been included in section 4.6 of the revised version.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have satisfactorily responded to all my questions and made the necessary changes to the manuscript. Therefore, I recommend the present manuscript for further publication.
