Review on Water and Energy Integration in Process Industry: Water-Heat Nexus

Round 1

Reviewer 1 Report

The work presents a literature review on water and energy integration in process industry. Authors also propose an early concept of a superstructure-based approach that could improve energy/water integration. The work has some language flaws that must be revised prior to publication.

Some points I believe are worth raising: the main purpose of this work is to present a review and a brief introduction to an incipient idea for heat and water recirculation. The literature review could be more specific, presenting deeper concepts of cited works instead of simply presenting lists of papers for each approached aspect. Moreover, the concept presented, although interesting, seems at an embryonic stage. Some further discussion should be presented such as the computational viability of implementing such a superstructure. Would simulators be required? Could the model be simplified to some extent? I would also suggest that at least parts of the main material/energy balances are presented in some form.

Some other points related to language and figures:

Line 10 – in the scope of improving;

Line 40 – Authors of the present study?

Line 58 – Overall, such … requires. Is a word missing in that sentence?

Line 62 – Such has been established… Please check the use of the word “such”.

Some sentences are too long, e.g., lines 92-95 and 100-106.

Figure 1 could be improved. Please include some text to all icons describing what each of them represents. Blocks with questions are not always clear. For instance, those with “sustainable?”. What happens if or if not sustainable?

The literature review presented in Tables 2, 3 and 4 is, to some extent, vague. I am not sure presenting a set of lumped references to each mentioned aspect is the best way to provide the reader with guidance on progress in these areas. Some main aspect of those works could be highlighted.

Author Response

The work presents a literature review on water and energy integration in process industry. Authors also propose an early concept of a superstructure-based approach that could improve energy/water integration. The work has some language flaws that must be revised prior to publication.

Manuscript has been carefully revised to correct scientific language and grammatical errors.

 

Some points I believe are worth raising: the main purpose of this work is to present a review and a brief introduction to an incipient idea for heat and water recirculation. The literature review could be more specific, presenting deeper concepts of cited works instead of simply presenting lists of papers for each approached aspect. Moreover, the concept presented, although interesting, seems at an embryonic stage. Some further discussion should be presented such as the computational viability of implementing such a superstructure. Would simulators be required? Could the model be simplified to some extent? I would also suggest that at least parts of the main material/energy balances are presented in some form.

Thanks for this, we fully agree. A further description of the general concept presented in Figure 5 has been added. Also sections 4.1 and 4.2 have been added for the synthesis of mass/ enthalpy equations and the existing computational tools, respectively.

 

Some other points related to language and figures:

Line 10 – in the scope of improving;

It has been changed accordingly.

 

Line 40 – Authors of the present study?

 “study” was added accordingly.

 

Line 58 – Overall, such … requires. Is a word missing in that sentence?

Indeed, it has been changed to: “such implementations” for a better understanding of the sentence.

 

Line 62 – Such has been established… Please check the use of the word “such”.

Amended to “These concepts are (…)” for better understanding of the sentence.

 

Some sentences are too long, e.g., lines 92-95 and 100-106.

Indeed, the sentences have been shortened by separating them in two or more sentences.

 

Figure 1 could be improved. Please include some text to all icons describing what each of them represents. Blocks with questions are not always clear. For instance, those with “sustainable?”. What happens if or if not sustainable?

Figure 1 has been updated to include a further description of icons and streams, including a more discernible picture of the scenarios of “Yes” and “No” to if it is “sustainable” or “reusable”.

 

The literature review presented in Tables 2, 3 and 4 is, to some extent, vague. I am not sure presenting a set of lumped references to each mentioned aspect is the best way to provide the reader with guidance on progress in these areas. Some main aspect of those works could be highlighted.

Indeed. The information of Tables 2 to 4 has been updated to include more specific aspects. Information related to the benefits brought by the installation of these technologies has been added. As such also its characterisation has been added within Tables 3 and 4 (savings and payback time). In respect to Table 2, the following aggregated conclusion has been added:

By the analysis of Table 2, it is observed that process integration in respect to heat recovery and water recirculation have been successfully developed through numerical models for further industrial implementations. Research in this field has also attended for the requirements of related areas, such as energy management and water management. The existing methodology of Combined Water and Energy Integration reveals to be effective for the minimization of the use of freshwater and hot/ cold utilities in a water system with a variable number of water-using processes. This corresponds to approach of Water-Heat Nexus concept. It considers, although, the analysis of water streams as the only streams to be recirculated and single type of process (in this case a water network). Therefore, the integration of the aforementioned technologies is relevant in the scope to expand the applicability of this approach.

Reviewer 2 Report

Manuscript number: sustainability-1744996

The manuscript entitled " Review on Water and Energy Integration in Process Industry: Water-Heat Nexus" presents a comprehensive study on a noteworthy topic that is well-aligned with the scope of the Journal.

The idea of the proposed system is good, however, Water and Energy Integration Systems (WEIS) for Process Industry section need to be described further.

Also, the references are required whereever some figure/table/data is take from a source of adopted/modified a Figure or Table.

Manuscript lacks in the scientific language and some grammatical error also need to be omitted.  

Author Response

The manuscript entitled " Review on Water and Energy Integration in Process Industry: Water-Heat Nexus" presents a comprehensive study on a noteworthy topic that is well-aligned with the scope of the Journal.

The idea of the proposed system is good, however, Water and Energy Integration Systems (WEIS) for Process Industry section need to be described further.

Thanks for this. A further description of the general concept presented in Figure 5 has added. Also, new sections 4.1 and 4.2 have been added for the synthesis of mass/ enthalpy equations, and existing computational tools, respectively.

 

Also, the references are required wherever some figure/table/data is take from a source of adopted/modified a Figure or Table.

For each Figure and Table which has been adapted from existing literature, the corresponding references were added.

 

Manuscript lacks in the scientific language and some grammatical error also need to be omitted.  

Manuscript has been carefully revised to correct scientific language and grammatical errors.

Round 2

Reviewer 1 Report

My main concerns regarding the superstructure have been solved. It is presented in a concise, more interesting form now.

However, I am afraid the literature review is still not satisfactory. For example, in the last row of Table 3, the authors cite [119,163– 198]. This is lumped list of more than 30 works with only a single paragraph to describe them. No further information on specific methodologies applied by each one of them. Each published work is, in general, novel and presents some contribution to science. At least some specific aspect of each work must be present. If that is not possible, smaller lumped groups (up to three or four) with specific similarities can be presented. Take, for comparison, the description for HRSG, also in table 3. As for the 30 works aforementioned, a single paragraph is dedicated to describe those two works.

More than 30 lumped works is not reasonable in a single citation of a literature review. Authors should rework these aspects. There are other cases of 10+ lumped citations.

Author Response

My main concerns regarding the superstructure have been solved. It is presented in a concise, more interesting form now.

However, I am afraid the literature review is still not satisfactory. For example, in the last row of Table 3, the authors cite [119,163– 198]. This is lumped list of more than 30 works with only a single paragraph to describe them. No further information on specific methodologies applied by each one of them. Each published work is, in general, novel and presents some contribution to science. At least some specific aspect of each work must be present. If that is not possible, smaller lumped groups (up to three or four) with specific similarities can be presented. Take, for comparison, the description for HRSG, also in table 3. As for the 30 works aforementioned, a single paragraph is dedicated to describe those two works.

More than 30 lumped works is not reasonable in a single citation of a literature review. Authors should rework these aspects. There are other cases of 10+ lumped citations.

 

Thank you for the suggestion. Amendments have been done in Table 3 and also Table 6, in which specific references have been added to the main text in order to characterise aspects associated to each technology/ type: i) different designs/ configurations for Air-gas heat ex-changers; ii)  Air preheaters; iii) different phase change material (PCM) heat exchanger; iv) different software for simulations and; v)  different methodologies for optimisation simulations.

In our view, this is a good way to guide the readers, as the main aspects associated to each point are differentiated.