Effect of ozone pretreatment and densification parameters on the physical, mechanical and fuel characteristics of bagasse briquettes

Document Type : Research Paper

Authors

• Hosein Shafaei ¹
• Ali mashaallah Kermani ²
• Ehsan Sarlaki ³
• Mohammad hossein Kianmehr ⁴

¹ Department of Agrotechnology, College of Agricultural Technology (Aburiahan), University of Tehran

² Department of Agro-technology Engineering,, Aburaihan Campus, University of Tehran, Tehran, Iran

³ Department of Agrotechnology, College of Agricultural Technology, University of Tehran, Pakdasht, Tehran, Iran

⁴ Department of Agrotechnology

Abstract

Keywords

• Calorific value
• Sugarcane bagasse
• Fuel briquette
• Ozonation pretreatment
• Toughness

Main Subjects

• ؟؟

Effect of ozone pretreatment and densification parameters on the physical, mechanical, and fuel characteristics of bagasse briquettes

EXTENDED ABSTRACT

Introduction

Among renewable energy resources, biomass has the potential to serve as a sustainable alternative to fossil fuels. However, the significant distance between the source of biomass and its point of use results in high transportation costs due to factors such as high moisture content, irregular shapes, and low density. Additionally, the direct combustion of biomass presents challenges related to its high moisture content, low volumetric density, and limited energy potential. These issues can be mitigated through densification into briquettes, a process that produces a solid and dense fuel with consistent properties. To enhance the physical, chemical, and thermal characteristics of lignocellulosic biomass for biofuel production, pretreatment is often necessary. Ozone, being a powerful oxidant, can be utilized for biomass pretreatment due to its ability to cleave carbon-carbon double and triple bonds, such as those found in lignin. This study aims to examine the effects of various ozonation pretreatment variables and the densification process on the quality of briquettes while also assessing their physical, mechanical, and chemical properties.

Materials and Methods

The sugarcane bagasse used in this study was provided by Haft Tappeh Sugarcane Agro-Industry Co., located in Khuzestan province, Iran. Optimizing the effect of ozonation pretreatment in the production of briquettes was performed using a hydraulic press. The independent variables were the size of bagasse particles (≤1.18, 1.18-2.36, and 2.36-4.75 mm), the mold temperature (280, 320, and 360 °C), the moisture content of bagasse in ozonation reactor (20, 35, and 50% w.b.) and time duration of ozonation (15, 25, and 35 minutes). The dependent variables were the toughness and relaxed density of briquettes. The experiments were designed using the response surface methodology (RSM) based on a central composite design (CCD) in Design Expert v.11 software. The ozonation process was performed in a fixed bed cylindrical reactor made of transparent plexiglas on a laboratory scale. For each treatment, a 6 g bagasse sample was placed in a stainless-steel container inside the reactor. Oxygen concentrator with 93% high purity, and the output ozone concentration was 30 g/h. Based on proximate analysis and measurement of moisture content, volatile matter, ash, and fixed-carbon content have been used to predict the higher calorific value of briquettes through validated experimental equations.

Results

The results showed that by decreasing the particle size, the density of the produced briquettes increased. Ozone pretreatment showed a significant effect on briquette quality, especially density. The maximum value of the briquette density of ozone-pretreated bagasse was 1076 kg/m³, higher than the corresponding amount without pretreatment was 873 kg/m³. The results showed that by increasing the moisture content of bagasse up to 30% in the ozonation process, the toughness of the briquettes increased. After that, the toughness decreased when the moisture content increased to 50%. The ozone pretreatment enhanced the calorific value of bagasse briquettes produced compared to briquettes without pretreatment. The results showed that ozonation pretreatment in the briquette production process increased its calorific value from 16.61 to 17.85 MJ/kg. This issue concerns increasing the percentage of fixed carbon and reducing volatile matter in the ozonation pretreatment process. Previous research has shown that the physical properties of briquettes, including density, affect their calorific value. Generally, the briquettes with a better compression process and higher density will have a higher calorific value. Briquette production was favored at higher values of density and toughness, and at lower values of ozonation time duration and mold temperature. Using the desirability function-based optimization, optimal points with the highest desirability value (≥ 0.8) were determined. At the optimal point, the density and toughness were 982.31 kg/m³ and 249.934 kPa, respectively.

Conclusions

The assessment of the operating parameters of ozone pretreatment in producing fuel briquettes showed that the moisture content and particle size of bagasse had the most effects on the density and toughness of briquettes. Optimum briquette production conditions were determined at 15 minutes of ozonation, bagasse particle size smaller than 1.18 mm, moisture content 33.448% (w.b.) and brequetting temperature 280 °C. The optimal values of briquette density and toughness responses were obtained as 982.310 kg/m³ and 249.934 kPa, respectively. In general, ozone pretreatment improved the properties of sugarcane bagasse fuel briquettes. The calorific value of fuel briquettes produced from ozone-treated bagasse under optimal conditions was 17.85 MJ/kg, while this value was 16.61 MJ/kg for no pretreatment.

CRediT authorship contribution statement

Hussain Shafaie: Writing – original draft, Methodology, Data curation, Software, Formal analysis; Ali Mashaallah Kermani: Writing – review and editing, Conceptualization, Supervision, Project administration, Methodology, Visualization, Investigation, Validation; Ehsan Sarlaki: Writing – review and editing, Formal analysis, Investigation, Data curation, Validation, Resources; Mohammad Hossein Kianmehr: Supervision, Project administration, Methodology, Resources.

Data Availability Statement

Data available on request from the authors. All the data used in this original research are presented throughout the text and in the form of Tables and Figures.

Ethical considerations

The authors avoided from data fabrication and falsification.

Acknowledgments

The authors extend their sincere appreciation to the University of Tehran for their support throughout this project.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.