Simulation and Experimental Validation on the Effect of Twin-Screw Pulping Technology upon Straw Pulping Performance Based on Tavares Mathematical Model
Round 1
Reviewer 1 Report
1. The research work offers a great opportunity for straw application after the shutdown of the most of this type of non-wood pulp and paper mills in China.
2. Based on your options, is there any potential application/market for using the generated pulp (or biomass) after twin-screw pulping machine?
3. Is there any other equipment involved in generating straw pulp? Pulp with mechanical treatment only may not have any advantages compared to other market pulps.
4. Are there any other parameters to be considered for assessing pulping performance instead of pulping yield only? e.g., generated pulp properties, energy consumption, impact on GHG reduction, etc.?
5. Lignin may not be able to be degraded via mechanical twin-screw press treatment. During the mechanical twin-screw press treatment, part of the hemicellulose and extractives etc. would be removed and resulting in a yield loss. Please revise your explanations.
6. Better to involve some basic wood/non-wood chemistry in the explaining of the mechanism of twin-screw pressing, e.g., what happens for cellulose, hemicellulose and lignin, etc.
Author Response
Response to Reviewer 1 Comments
Dear reviewers：
Thank you for your letter and for the comments from reviewers concerning our manuscript entitled “Simulation and experimental validation on the effect of twin-screw pulping technology upon straw pulping performance based on Tavares mathematical model”. We thank the reviewers for the time and effort that they have put into reviewing the previous version of the manuscript. Your suggestions comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Accordingly, we uploaded the file of the revised manuscript by using the track changes mode in MS Word. Revised portion are marked in red in the paper. Appended to this letter is our point-by-point response to the comments raised by the reviewers.
Point 1: The research work offers a great opportunity for straw application after the shutdown of the most of this type of non-wood pulp and paper mills in China.
Response 1: Thanks for your acknowledgement of this study. Your encouragement will give us more motivation to carry out subsequent research work, and in the future, we will study the mechanism of microbial degradation on the lignin of straw deeply, and try to promote the application of straw in paper making and other aspects in China.
Point 2: Based on your options, is there any potential application/market for using the generated pulp (or biomass) after twin-screw pulping machine?
Response 2: Thanks for your very insightful comments. According to relevant data [1], many enterprises in China are conducting research related to straw pulping, and the investment amount is huge, which shows its great market value. The pulp produced by the twin-screw pulping machine can become the raw material for straw industrial products such as industrial paper, degradable packaging materials and strawboard.
Point 3: Is there any other equipment involved in generating straw pulp? Pulp with mechanical treatment only may not have any advantages compared to other market pulps.
Response 3: Thanks for your friendly advice. The production of straw pulp in the industry also needs some common small equipment such as feeding devices, mixers, etc. The relevant studies show that twin-screw pulping has the advantage of low energy consumption. In this study, before entering the twin-screw pulping machine, the straw was first treated with white rot fungi. I am sorry that this part was lost in the writing of the paper, and it has been added on page 9, lines 284-290. The microbial formulation will be the next step of the topic. This study applied a combination of mechanical and biological methods for straw pulping, integrating the operations of conveying, mixing and pressing. It will consume less energy, pollute less, cost less and have higher straw yield compared to other pulps in the market.
Point 4: Are there any other parameters to be considered for assessing pulping performance instead of pulping yield only? e.g., generated pulp properties, energy consumption, impact on GHG reduction, etc.?
Response 4: Thanks for your very useful advice. Based on the previous research about the low energy consumption [2] and good pulping characteristics [3] of twin-screw pulping, this study simulated the movement of straw particles in the twin-screw pulping machine by using the Discrete Element Method. In this study, macroscopic and microscopic indicators were combined to study the pulp morphology of straw and the characteristics of the straw boards such as blowholes and trichomes to comprehensively evaluate the performance of straw pulping. According to your very useful advice, the next research will consider more pulp characteristics indicators and environmental-related indicators.
Point 5: Lignin may not be able to be degraded via mechanical twin-screw press treatment. During the mechanical twin-screw press treatment, part of the hemicellulose and extractives etc. would be removed and resulting in a yield loss. Please revise your explanations.
Response 5: Thanks for your very careful advice. I am sorry to ignore the degradation process of the hemicellulose and extractives in the twin-screw pulping process, and it has been added on page 11, line 320 for the relevant content. I apologize for the misunderstanding due to my unclear presentation. The improvement of straw pulp yield in this study refers to the relative results of different experimental parameters, rather than due to the degradation behavior of hemicellulose and extractives, which has been modified on page 15, line 408. According to the relevant study [4], the fibers passing through the twin-screw pulper always present a certain level of fibrillation as well but are unable to completely degrade the lignin. The straw pulp in this work was pulped by a combination of mechanical and biological methods. The pulp was treated with white rot fungi before entering the twin-screw pulping machine to partially destroy the lignin structure. This paper focuses on the improvement of pulping performance due to sufficient degradation of straw lignin after the straw pulp treated by white rot fungi entered the twin-screw pulping machine. The next step will focus on the effect of more different bacteria on the degradation of straw lignin, to provide more ideas and methods for the Chinese straw pulping industry more fully.
Point 6: Better to involve some basic wood/non-wood chemistry in the explaining of the mechanism of twin-screw pressing, e.g., what happens for cellulose, hemicellulose and lignin, etc.
Response 6: Thanks for your very patient advice. According to your friendly suggestion, this study vividly demonstrates the changes of lignin, cellulose and hemicellulose during the straw pulping process with graphics in section 2.3.1 Trial Preparation. This paper adds and refines the basic mechanism of straw pulping in Section 3.3 Results of the Validation Experiment.
Looking forward to hearing from you
Thank you and best regards
Dezhi, Ren(corresponding author) E-mail: [email protected] Tel: +86-13889215226.
Yuanjuan,Gong(corresponding author) E-mail: [email protected] Tel: +86-13998240253.
Address: Agricultural Mechanization Laboratory, College of Engineering, Shenyang Agricultural University, Shenyang 110866, China.
References
[1] https://www.qcc.com/web/search?key=%E7%A7%B8%E7%A7%86%E9%80%A0%E7%BA%B8
[2] ESPINOSA E, ROL F, BRAS J, et al. Production of lignocellulose nanofibers from wheat straw by different fibrillation methods. Comparison of its viability in cardboard recycling process [J]. Journal of Cleaner Production, 2019, 239.
[3] LIANG F, FANG G, JIAO J, et al. The Use of Twin Screw Extruder Instead of Model Screw Device During Bamboo Chemo-mechanical Pulping [J]. Bioresources, 2018, 13(2).
[4] ROL F, KARAKASHOV B, NECHYPORCHUK O, et al. Pilot-Scale Twin Screw Extrusion and Chemical Pretreatment as an Energy-Efficient Method for the Production of Nanofibrillated Cellulose at High Solid Content [J]. Acs Sustainable Chemistry & Engineering, 2017, 5(8): 6524-31.
Author Response File: 
Author Response.doc
Reviewer 2 Report
- On page 9, line 250, explain the abbreviations W, S, R.
- Page 12, line 321 - name of figure 10 - it is necessary to write that the simulation process is shown. The proposed title of the figure would be "Simulation of breaking of straw particles in a twin screw machine for cellulose in time for 0 s (a), 3 s (b), 6 s (c), 9 s (d), 12 s (e), 15 s (f), 18 s (g) and 21 s (h)".
- In Table 4, factors A, B, and C must be given their full names.
- The recommended name for Table 4 is: "Analysed factors of the experiment"
- In the name of Figure 11, images a), b) and c) must be described.
-It is recommended to change the name of Figure 13 as follows: "Illustration of straw pulp with different moisture content. Straw moisture content is 50% (a), 55% (b), 60% (c), 65% (d), 70% (e), and 75% (f)".
-Parts of Figure 14 are interrupted - check that the images are sent in the required format.
- Figure 14 shows curves/graphs. To understand them, labels and units of measure must be written on the coordinate axes; labels in the legend should be written in the same way. Labels (a), (b)....under the figures should be written in the same way as throughout the paper.
- Page 19, line 525 - does this refer to multiple angles or to one angle; it is necessary to put a comma after each angle.
- Throughout the paper, the spaces after the dot or comma must be checked.
Author Response
Response to Reviewer 2 Comments
Dear reviewers：
Thank you for your letter and for the comments from reviewers concerning our manuscript entitled “Simulation and experimental validation on the effect of twin-screw pulping technology upon straw pulping performance based on Tavares mathematical model”. We thank the reviewers for the time and effort that they have put into reviewing the previous version of the manuscript. Your suggestions comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Accordingly, we uploaded the file of the revised manuscript by using the track changes mode in MS Word. Revised portion are marked in red in the paper. Appended to this letter is our point-by-point response to the comments raised by the reviewers.
Point 1: On page 9, line 250, explain the abbreviations W, S, R.
Response 1: Thanks for your carefully review, the abbreviations W, S, R have been explained in Table 2.
Point 2: Page 12, line 321 - name of figure 10 - it is necessary to write that the simulation process is shown. The proposed title of the figure would be "Simulation of breaking of straw particles in a twin screw machine for cellulose in time for 0 s (a), 3 s (b), 6 s (c), 9 s (d), 12 s (e), 15 s (f), 18 s (g) and 21 s (h)".
Response 2: Thanks for your helpful advice. The name of figure 10 has been modified as your kindly advice "Simulation of breaking of straw particles in a twin screw machine for cellulose in time for 0 s (a), 3 s (b), 6 s (c), 9 s (d), 12 s (e), 15 s (f), 18 s (g) and 21 s (h)" from your helpful advice.
Point 3: In Table 4, factors A, B, and C must be given their full names.
Response 3: Thanks for your kindly advice. The factors A, B, and C have been given their full names.
Point 4: The recommended name for Table 4 is: "Analysed factors of the experiment"
Response 4: According to the suggestion of the reviewer. The name for Table 4 has been changed to the recommended name "Analysed factors of the experiment".
Point 5: In the name of Figure 11, images a), b) and c) must be described.
Response 5: We thank the reviewer for pointing this out. The name of Figure 11 has been described as “Response surface graph of the effect of interactions on the straw pulping rate. (a) The effects of screw speed (B) vs. tooth groove angle (A) on pulping yield; (b) The effects of straw moisture content (C) vs. tooth groove angle (A) on pulping yield; (c) The effects of straw moisture content (C) vs. screw speed (B) on pulping yield”.
Point 6: It is recommended to change the name of Figure 13 as follows: "Illustration of straw pulp with different moisture content. Straw moisture content is 50% (a), 55% (b), 60% (c), 65% (d), 70% (e), and 75% (f)".
Response 6: Thanks for your very careful advice. The name of Figure 13 has been changed to "Illustration of straw pulp with different moisture content. Straw moisture content is 50% (a), 55% (b), 60% (c), 65% (d), 70% (e), and 75% (f)".
Point 7: Parts of Figure 14 are interrupted - check that the images are sent in the required format.
Response 7: We thank the reviewers for this suggestion. The images in Figure 14 have been checked and corrected.
Point 8: Figure 14 shows curves/graphs. To understand them, labels and units of measure must be written on the coordinate axes; labels in the legend should be written in the same way. Labels (a), (b)....under the figures should be written in the same way as throughout the paper.
Response 8: Thank you for your very patient advice. The labels and units of measure have been written on the coordinate axes. The labels in the legend have been written in the same way.
Point 9: Page 19, line 525 - does this refer to multiple angles or to one angle; it is necessary to put a comma after each angle.
Response 9: We thanks for your kindly reminding. This part means a multi-angle combination form, not a single angle, so " - " was used between the angles instead of the comma.
Point 10: Throughout the paper, the spaces after the dot or comma must be checked.
Response 10: Thank you for your sincere advice. The spaces after the dot or comma have been checked throughout the paper.
Looking forward to hearing from you
谢谢你和最诚挚的问候
任德志（通讯作者） 邮箱：[email protected] 电话：+86-13889215226。
龚元娟（通讯作者） 邮箱： [email protected] 电话： +86-13998240253.
地址：沈阳农业大学工学院农业机械化实验室，沈阳110866
Author Response File: Author Response.doc
Round 2
Reviewer 1 Report
Thank you very much for your considerations regarding the previous comments, great work and look forward for your future contributions to the industry.
