An Experimental and Theoretical Study of the Gasification of Miscanthus Briquettes in a Double-Stage Downdraft Gasifier: Syngas, Tar, and Biochar Characterization

Tejasvi Sharma, Diego M. Yepes Maya, Francisco Regis M. Nascimento, Yunye Shi, Albert Ratner, Electo E. Silva Lora, Lourival Jorge Mendes Neto, Jose Carlos Escobar Palacios and Rubenildo Vieira Andrade
Additional contact information
Tejasvi Sharma: Department of Mechanical Engineering, University of Iowa, Iowa, IA 52246, USA
Diego M. Yepes Maya: Mechanical Engineering Institute, Federal University of Itajubá (UNIFEI), Itajuba, MG 37500-103, Brazil
Francisco Regis M. Nascimento: Mechanical Engineering Institute, Federal University of Itajubá (UNIFEI), Itajuba, MG 37500-103, Brazil
Yunye Shi: Department of Engineering and Physics, St. Ambrose University, Davenport, IA 52803, USA
Albert Ratner: Department of Mechanical Engineering, University of Iowa, Iowa, IA 52246, USA
Electo E. Silva Lora: Mechanical Engineering Institute, Federal University of Itajubá (UNIFEI), Itajuba, MG 37500-103, Brazil
Lourival Jorge Mendes Neto: Mechanical Engineering Institute, Federal University of Itajubá (UNIFEI), Itajuba, MG 37500-103, Brazil
Jose Carlos Escobar Palacios: Mechanical Engineering Institute, Federal University of Itajubá (UNIFEI), Itajuba, MG 37500-103, Brazil
Rubenildo Vieira Andrade: Mechanical Engineering Institute, Federal University of Itajubá (UNIFEI), Itajuba, MG 37500-103, Brazil

Energies, 2018, vol. 11, issue 11, 1-23

Abstract: The goal of this work is to understand the gasification process for Miscanthus briquettes in a double-stage downdraft gasifier, and the impact of different Equivalence Ratios (ER) on syngas, biochar, and tar characteristics. The optimal ER was found to be 0.35, which yielded a syngas maximum heating value of 5.5 MJ/Nm 3 with a syngas composition of 20.29% CO, 18.68% H 2 , and 0.86% CH 4 . To better understand the observed behavior, an equilibrium reaction model was created and validated using the experimental data. The model showed that the heating value decreased with increasing ER, and that hydrogen production peaked at ER = 0.37, while methane (CH 4 ) became negligible above ER = 0.42. Tar and particle content in the gas produced at a certain temperature can now be predicted. To assess the biochar characteristics, surface structure image analysis and a surface area porosity analysis were carried out. Employing images from a scanning electron microscope (SEM), the biochar cell bonds and pore structures were examined and analyzed. By using the Brunauer-Emmett-Teller (BET) analysis of the surface porosity, the surface area to be 186.06 m 2 /g and the micro pore volume was calculated to be 0.07 m 3 /g. The final aspect of the analysis involved an evaluation of tar production. Combining current and prior data showed a logarithmic relationship between the amount of tar produced and the gasifier bed temperature, where the amount of tar produced decreased with increasing bed temperature. This results in very low tar levels, which is one of the known advantages for a double-stage downdraft gasifier over a single-stage system.

Keywords: biomass; gasification; biochar; tar; downdraft reactor; producer gas (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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