Residence Time Distribution of Non-Spherical Particles in a Continuous Rotary Drum

Round 1

Reviewer 1 Report

The authors of this work look at how the shape of particles affects the residence time distribution in a continuous rotary drum. The main issue is that the particles here are merely cubic in shape, lacking comparison with spherical particles or other particle shapes. Therefore, it is still not clear how a particle shape makes differences compared to another.

The paper can be considered for publication if the authors use more particle shapes in their experiments.

Author Response

Other shapes of particles were investigated in depth by other researches as we reviewed some of the most important contributions in the article. In this article, we investigated particles with sharp edges and compared our results to other shapes (reported by others) as much as possible in depth. In this way, we could give a clear view of the similarities and differences between the flow behavior of particles with sharp edges and without sharp edge.  
We also checked the text for grammar errors and revised.

Author Response File: Author Response.docx

Reviewer 2 Report

The article is interesting with regard to the achieved results.

These results can be a good basis for DEM simulations. Several assumptions of the impact of higher speed and the size of the inclination of the rotating cylinder were confirmed.

 

Main shortcomings:

• Incorrect numbering of chapters and headings.
• Figure 2. The arrow (position f) does not point to the motor.
• Labeling Figure 5, problems in the visualization of labels.
• It is not clear from the text what experiment 1-3 and ADM 1-3 mean. Is this a repetition of the same experiment setup 3 times? Add to the description of measurement methods.
• What about figure 5 e) with slope? The largest slope of 4 ° lasted the shortest time and with 3 ° the longest? Placed positions are not unambiguous.
• Why for higher flow 1.08 vs. 0.67 cm3 / s does the RTD increase? Add in the conclusion section.
• Figure 8. Repair scattered items.
• Figure 10 a) better describe the ratios of wood and ceramic content. It is not entirely clear how this is meant: Figure 10 (a) shows the effect of wood volume fraction on the MRT (the ceramic volume fraction is 1-wood volume fraction).
• It is not entirely clear from the text what it is like with tracking particles and Figure 10. What are the ratios of whether tracking particles have been used?
• Is the greater retention of wood particles really due to the surface roughness? Isn't it because of the lower particle weight? Could it be supplemented by simple experiments or friction measurements of wood and ceramic particles?
• The effects on the achieved results could be better specified in the conclusions section.

Author Response

• Incorrect numbering of chapters and headings.

  • We checked and made necessary changes.

• Figure 2. The arrow (position f) does not point to the motor.

  • We corrected the labels on this figure.

• Labeling Figure 5, problems in the visualization of labels.

  • Corrected

• It is not clear from the text what experiment 1-3 and ADM 1-3 mean. Is this a repetition of the same experiment setup 3 times? Add to the description of measurement methods.

  • We clarified this in the captions of Figure 6 and Table 2. We also mentioned in section #2 that each experiment was repeated 3 times.

• What about figure 5 e) with slope? The largest slope of 4 ° lasted the shortest time and with 3 ° the longest? Placed positions are not unambiguous.

  • We repositioned labels and we think that it is now unambiguous.
    
    

• Why for higher flow 1.08 vs. 0.67 cm3 / s does the RTD increase? Add in the conclusion section.

  • We added some explanation to conclusion section.

• Figure 8. Repair scattered items.

  • Corrected

• Figure 10 a) better describe the ratios of wood and ceramic content. It is not entirely clear how this is meant: Figure 10 (a) shows the effect of wood volume fraction on the MRT (the ceramic volume fraction is 1-wood volume fraction).

  • Yes, we meant the volume fraction of wooden particles in the feed. We clarified this in the caption of the figure and made some changes in the text too.

• It is not entirely clear from the text what it is like with tracking particles and Figure 10. What are the ratios of whether tracking particles have been used?

  • The information is given in Table 1. We kept the ratio of wooden and ceramic tracers proportional to the volume fraction of each particle in the mixture. Some explanation is added to the text to clarify this more.

• Is the greater retention of wood particles really due to the surface roughness? Isn't it because of the lower particle weight? Could it be supplemented by simple experiments or friction measurements of wood and ceramic particles?

  • After carefully reviewing the captured movies in the experiments, we observed that the rapid avalanche of ceramic particles that causes ceramic particles travel a longer distance in each avalanche that in turn causes a shorter MRT. So, we revised our discussion in this section.

• The effects on the achieved results could be better specified in the conclusions section.

  • We added some major conclusions on the effect of flow rate, particle size and density on axial dispersion coefficient to this section.

Author Response File: Author Response.docx

Reviewer 3 Report

The paper presented by the authors entitled: "Residence time distribution of non-spherical particles in a continuous rotary drum", is of interest to researchers working in the area and is very well designed and presented.
rotary drum", is of interest to researchers working in the area and is very well designed and presented. 

However, before it is accepted for publication, I suggest the following changes:

1. Reorganise Table 1, to make it clearer.
2. Make a better analysis of the reuslts presented in Figures 5; additionally present it in a higher resolution.
3.  The results presented in Figure 6b should be better presented and discussed at length.
4. it is not clear why bold is used in Table 3.
5. the effect of the tilt angle presented in Figure 7 is not very clear what the authors want to present.
6. In Figure 8b, correct the super indices of the velocities.

 

Author Response

• Reorganise Table 1, to make it clearer.

  • Done.

• Make a better analysis of the reuslts presented in Figures 5; additionally present it in a higher resolution.

  • We changed all the figures and provided higher resolution versions. Our goal for presenting this figure was to compare trend of RTD at different conditions qualitatively and show how the RTD of particles looked like and how the ADM were fitted on them. We left the detailed discussion of the results to the next figures where we focused on the effect of each operating condition on the MRT and axial dispersion coefficient.

• The results presented in Figure 6b should be better presented and discussed at length.

  • We discussed the trends of axial dispersion coefficient at length, based on our observations in our experiments and compared them with other researchers results. For this end, we cited more articles that support our experimental observations and made some changes to this section.

• it is not clear why bold is used in Table 3.

  • We changed the font face to regular.

• the effect of the tilt angle presented in Figure 7 is not very clear what the authors want to present.

  • In Figure 7, we showed the effect of incline angle on the MRT and dispersion coefficient at two rotation speeds (5 rpm and 11 rpm). We showed that MRT is proportional to incline angle, MRT^-0.813 at 5 rpm and MRT^-1.344.

• In Figure 8b, correct the super indices of the velocities.

  • Done.
    
    
    

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have made an improvement in this revised version. The paper can now be accepted for publication.