The effect of microwave drying pretreatment on dry torrefaction of agricultural biomasses

Mahmoud Amer; Mohamed Nour; Mahmoud Ahmed; Shinichi Ookawara; Sameh Nada; Ahmed Elwardany

doi:10.1016/j.biortech.2019.121400

The effect of microwave drying pretreatment on dry torrefaction of agricultural biomasses

Bioresour Technol. 2019 Aug:286:121400. doi: 10.1016/j.biortech.2019.121400. Epub 2019 Apr 30.

Authors

Mahmoud Amer¹, Mohamed Nour², Mahmoud Ahmed³, Shinichi Ookawara⁴, Sameh Nada⁵, Ahmed Elwardany⁶

Affiliations

¹ Energy Resources Engineering Department, Egypt-Japan University of Science and Technology (E-JUST), P.O. Box 179-21934, New Borg El-Arab City, Alexandria, Egypt; Mechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria 21544, Egypt.
² Mechanical Engineering Department, Benha Faculty of Engineering, Benha University, 13512 Benha, Qalubia, Egypt.
³ Energy Resources Engineering Department, Egypt-Japan University of Science and Technology (E-JUST), P.O. Box 179-21934, New Borg El-Arab City, Alexandria, Egypt; Mechanical Engineering Department, Faculty of Engineering, Assiut University, 271516 Assiut, Egypt.
⁴ Department of Chemical Science and Eng., Tokyo Institute of Technology, Tokyo 152-8552, Japan.
⁵ Energy Resources Engineering Department, Egypt-Japan University of Science and Technology (E-JUST), P.O. Box 179-21934, New Borg El-Arab City, Alexandria, Egypt; Mechanical Engineering Department, Benha Faculty of Engineering, Benha University, 13512 Benha, Qalubia, Egypt.
⁶ Energy Resources Engineering Department, Egypt-Japan University of Science and Technology (E-JUST), P.O. Box 179-21934, New Borg El-Arab City, Alexandria, Egypt; Mechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria 21544, Egypt. Electronic address: ahmed.elwardany@ejust.edu.eg.

PMID: 31078983
DOI: 10.1016/j.biortech.2019.121400

Abstract

This paper examines the effect of microwave drying on biomass characteristics and subsequent dry pyrolysis and characteristics of produced biochar from rice straw, sugarcane bagasse, rice husk and cotton stalk compared to oven drying at 105 °C. Dried samples from both methods are torrefied at 250 and 300 °C with 30-minutes residence time. Drying time reached 60 times faster with microwave. The fast and violent microwave drying ruptured the biomasses' surface, releasing more volatiles and having lower crystallinity; these lowered the heating value, energy yield and elemental carbon compared to oven drying except for cotton stalk only due to its woody nature which reduced devolatilization. Sugarcane, rice husk and cotton stalk have the most promising values of elemental carbon, energy yield and heating value reaching that of the bituminous coal. Torrefied rice straw showed high crystallinity of 50.7% while sugarcane and rice husk were completely amorphous.

Keywords: Biochar; Biomass pyrolysis; Microwave drying; Torrefaction.

MeSH terms

Agriculture
Biomass
Heating
Microwaves*
Saccharum*