Non-Conventional Cuts in Batch Distillation to Brazilian Spirits (cachaça) Production: A Computational Simulation Approach
Round 1
Reviewer 1 Report
The simulations described in the manuscript provide an interesting evaluation of alternative strategies for making cuts in traditional pot still distillation. While it seems the industry could also benefit from additional evaluation of fermentation practices, the simulation provide interesting insight into how the range of congener concentration in the fermented mash impacts the distillation outcomes.
The discussion of the validation of the modeling using alternate starting points to match Scanavini's could be more thoroughly discussed, particularly with regards to whether the use of different initial conditions can be used to adequately validate the simulations with different conditions, particularly given that differences between the simulation and the experimental could be explained by fluctuations in process parameters during the beginning of the experimental process.
The captions for Figures 5,7 & 8 could be improved, particularly for number 8. It would be worthwhile to direct readers' attention to the initial mass fraction percentages for each row in Figure 8, for example.
While 8 of 9 of the difficult fermentations still exceed legal requirements with the novel cuts, the improved spirit yields for the rest of the fermentations still provide a good validation of the simulation approach as a tool for improving distillations
Author Response
We improved the discussion regarding the differences in the begging og distillation:
The simulation of batch distillation calculates, for each time, the molar fraction of component i that is being vaporized. The amount vaporized is then defined by multiplying this mole fraction by the amount of liquid inside the pot still. In this way, small differences in the vaporized mole fraction are amplified when there are more liquid in the pot still, like at the beginning of the process. For the same reason, the experimental data from Scanavini [38] showed greater oscillations at the beginning of distillation.
The captions of Figures 5, 7 and 8 were improved, as suggested:
Fig 5 Characteristic curve of the cutting ranges. The axis x represents the “head”, i.e. the first cut. The axis y represents the heart, i.e. the second cut. All the shaded regions represent distilling cuts possibilities. The grey scale varies with ethanol concentration, from 38 % (v/v) (light) to 48 % (v/v) (dark)
Figure 7. Ratio between mass fractions of the selected minor compound and ethanol (EtOH) in the fermented musts: a) Acetic acid, b) acetaldehyde, c) Ethyl acetate, d) sum of higher alcohols (1-propanol + isobutanol + isoamyl alcohol)
Figure 8. Cut ranges for the analysis of the influence of each minor component. The simulated fermented musts have compositions formed only of ethanol , and the substance of interest (varying, values in legend) and water (determined by difference). The grey scale varies from 38 % (v/v) (light) to 48 % (v/v) (dark)
Reviewer 2 Report
This work has great contribution and is of great interest to readers in the area as they develop an algorithm to determine different possibilities of distillation cuts to support productivity and improve the final quality of cachaça, a Brazilian spirit drink. They used the Aspen Plus® software, generating twenty-four simulations considering eight compounds as follows: water and ethanol (major compounds); acetic acid, acetaldehyde, ethyl acetate, 1-propanol, isobutanol and isoamyl alcohol (minor compounds). Its algorithm made it possible to identify innumerable distillation cuts, resulting in products with different alcoholic strengths and process yields. the concentration ratio of acetaldehyde and ethanol was the key parameter to determine if the fermented musts could provide products that complied with the cachaça legislation.
However, there are some observations that need to be addressed.
1.- In the introduction it is necessary and urgent to add more references related to the process or other distillation and adsorption processes for the purification and separation of compounds. I place some works that can enrich this work:
“Torres Cantero, C. A., Lopez Lopez, G., Alvarado, V. M., Escobar Jimenez, R. F., Rumbo Morales, J. Y., & Sanchez Coronado, E. M. (2017). Control structures evaluation for a salt extractive distillation pilot plant: Application to bio-ethanol dehydration. Energies, 10(9), 1276.”
“Rumbo-Morales, J. Y., Lopez-Lopez, G., Alvarado, V. M., Valdez-Martinez, J. S., Sorcia-Vázquez, F. D. J., & Brizuela-Mendoza, J. A. (2018). Simulation and control of a pressure swing adsorption process to dehydrate ethanol. Revista Mexicana de Ingeniería Química, 17(3), 1051-1081.”
“Morales, J. Y. R., López, G. L., Martínez, V. M. A., Vázquez, F. D. J. S., Mendoza, J. A. B., & García, M. M. (2020). Parametric study and control of a pressure swing adsorption process to separate the water-ethanol mixture under disturbances. Separation and Purification Technology, 236, 116214.”
“Rumbo Morales, J. Y., Perez Vidal, A. F., Ortiz Torres, G., Salas Villalobo, A. U., Sorcia Vázquez, F. D. J., Brizuela Mendoza, J. A., ... & Valdez Martínez, J. S. (2020). Adsorption and Separation of the H 2 O/H 2 SO 4 and H 2 O/C 2 H 5 OH Mixtures: A Simulated and Experimental Study. Processes, 8(3), 290.”
“Morales, J. Y. R., Mendoza, J. A. B., Torres, G. O., Vázquez, F. D. J. S., Rojas, A. C., & Vidal, A. F. P. (2022). Fault-tolerant control implemented to Hammerstein–Wiener model: Application to bio-ethanol dehydration. Fuel, 308, 121836.”
“Ortiz-Torres, G., Rumbo-Morales, J. Y., Sorcia-Vázquez, F. D. J., Pérez-Vidal, A. F., Cruz-Rojas, A., Brizuela-Mendoza, J. A., & Oceguera-Contreras, E. (2021). Concentration estimation and fault tolerant control in a CSTR modelled as a quasi linear parameter varying system. Revista Mexicana de Ingeniería Química, 20(1), 51-66.”
“Rumbo Morales, J. Y., Ortiz-Torres, G., García, R. O. D., Cantero, C. A. T., Rodriguez, M. C., Sarmiento-Bustos, E., ... & García, M. M. (2022). Review of the Pressure Swing Adsorption Process for the Production of Biofuels and Medical Oxygen: Separation and Purification Technology. Adsorption Science & Technology, 2022.”
“López Núñez, A. R., Rumbo Morales, J. Y., Salas Villalobos, A. U., De La Cruz-Soto, J., Ortiz Torres, G., Rodríguez Cerda, J. C., ... & Pérez Vidal, A. F. (2022). Optimization and Recovery of a Pressure Swing Adsorption Process for the Purification and Production of Bioethanol. Fermentation, 8(7), 293.”
“Torres Cantero, C. A., Pérez Zúñiga, R., Martínez García, M., Ramos Cabral, S., Calixto-Rodriguez, M., Valdez Martínez, J. S., ... & Rumbo Morales, J. Y. (2022). Design and Control Applied to an Extractive Distillation Column with Salt for the Production of Bioethanol. Processes, 10(9), 1792.”
“Rumbo Morales, J. Y., López López, G., Alvarado, V. M., Torres Cantero, C. A., & Azcaray Rivera, H. R. (2019). Optimal Predictive Control for a Pressure Oscillation Adsorption Process for Producing Bioethanol. Computación y Sistemas, 23(4), 1593-1617.”
2.-It is necessary to add almost at the end of the Introduction section a paragraph of the contribution of this work.
3.- It is necessary to add at the end of the Introduction section a paragraph on how this work is divided.
4.- It is necessary to add a nomenclature table, add it in an annex.
5.-It is necessary to add a table of the starting nominal values ​​of the column. Add it in an annex.
6.-Conclude extensively and make a discussion about the investigation.
7.- Add a future work paragraph in the conclusion.
It is necessary to address these observations so that the article can be accepted.
Author Response
We would like to thank Reviewer for the nice suggestions.
1 and 2 - The following paragragh was included:
To the best of author’s knowledge, this work is pioneer in analyzing how the distilling cut may be used to overcome bad fermented musts, that at a first side could not be used to produce spirits within the legislation.
3 - The following paragragh was included:
This work is organized as follows. Section 2 presents the simulation details: VLE calculation and simulation approach, the description of a common commercial alembic, initial concentration of fermented musts available at literature and the here proposed algorithm. Section 3 describes the results: a comparison between experimental and simulated results, analysis of “cachaça” distilling cuts, evaluation of the most important minor compounds influencing distilling cut, description of new distilling cuts possibilities and their yields improvements. In Section 4 present the Conclusions and perspective of future works.
6 - We improved the Conclusion, however maintaing only the main conclusions. The discussion of the investigation is already in the section Results and Discussion.
7 - We included a perspective of future works.
Reviewer 3 Report
This article is bad in many ways：
(1) The article is less innovative and does not have a certain research necessity
(2) The literature review is not enough, not in-depth enough, many literatures are not comprehensive enough, and the connection between the literature is not good enough
(3) The research workload of the article is not enough, and many contents are further supplemented.
(4) Many data sources are unreliable
(5) The quality of some graphs can be further improved
Therefore I do not recommend this article to be published on Processes
Author Response
Comments not considered.
