Hydrodynamics of an Airlift Column for Aeration in Molten Sulfur

Round 1

Reviewer 1 Report

The abstract is well-written; it properly defines the research scope, describes the authors' contribution, and provides a highlight of the most important results. 

The introduction is well structured as well. It provides adequate  literature review with proper referencing and as expected it highlights the authors' contribution 

The methodology is excellent and its readability level is high. It describes the CFD technique properly 

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Major comment; 

1- Desply your mesh.

2-specify your mesh properties 

3- perform mesh sensitivity analysis 

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Minor comments

1-Please make sure that the figures are further described in the text.

 2- Please enhance the resolution of the figure.

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Best of luck (Major comment) 

Author Response

Thanks very much for taking your time to review this manuscript. We really appreciate all your generous comments and suggestions! Please find my revisions in the  attached document.

Author Response File: Author Response.pdf

Reviewer 2 Report

1. please check the formula and the text. it looks formula and text are high and low located.
2. There are many models to describe turbulence, k-∈ model is better than others? could you provide a comparison with other models?
3. how to ensure your results are correct? Are there any benchmark problems to show?

Author Response

Thanks very much for taking your time to review this manuscript. We really appreciate all your generous comments and suggestions! Please find my revisions in the  attached document.

Author Response File: Author Response.pdf

Reviewer 3 Report

• CFD modeling
  • It would be better to show B.C.s on the figure. Does ‘Opening outlet’ mean pressure outlet? Please define this boundary condition with more details.
  • How did you decide the gas superficial gas velocity range? Is it from the field or experimental data?
  • Table2 is not required. Rather than this table, it is more beneficial to show mesh independence. According to the text, mesh convergence studies are fulfilled, but there is proof that establishes this claim. The same issue is with the time step.
  • Gas material properties: did you consider the compressibility? It looks like you used constant density in your simulation.
  • Validation of the CFD setup. This paper is required to validate the CFD model with an experimental result. Currently, simulation is catching the general trend on both Liquid circulation velocity & height and superficial velocities, but the comparison error is 22-30% for some data sets.

“The fitting accuracy of the CFD simulation results and correlation should consider influences of the column geometry size and physical parameters simultaneously. The CFD simulation provides detailed information about hydrodynamics, which is beneficial for the understanding of the behavior of an airlift column for aeration in molten sulfur. “

-I highly recommend that you compare the superficial velocities of the simulation with a similar study(CFD or experimental); therefore, you can validate the setup before the further hydrodynamic analysis.  

Author Response

Thanks very much for taking your time to review this manuscript. We really appreciate all your generous comments and suggestions! Please find my revisions in the  attached document.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All comments have been revised properly. 

Reviewer 2 Report

Based on the added contents, I recommend the publication of this paper on Applied science.

Reviewer 3 Report

Thank you for clarification on the topics I mentioned. I still highly suggest to work on more validation the CFD setup with an experimental setup or a similar study. Due to fact, there is not many study on this area, CFD, I can accept the current study. 

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.