A Technical Analysis of Solid Recovered Fuel from Torrefied Jatropha Seed Residue via a Two-Stage Mechanical Screw Press and Solvent Extraction Process

Min-Hao Yuan,Tsung-Chi Hsu,Chia-Chi Chang,Manh Van Do,Duu-Jong Lee,Michael Huang,Yen-Hau Chen,Je-Lueng Shie,Yi-Hung Chen,Chang-Ping Yu,Chao-Hsiung Wu,Bo-Liang Liu,Far-Ching Lin,Ching-Yuan Chang,Cheng-Fang Lin

doi:10.3390/en14237876

Abstract

This study investigated the torrefaction of de-oiled Jatropha seed residue after a two-stage sequential process consisting of mechanical screw pressing and solvent extraction using n-hexane (denoted as JMS). The optimal torrefaction temperature (Tr) and torrefaction time (tr) were determined in the ranges of 260–300 °C and 10–60 min, respectively, so to achieve a better heating value and satisfactory energy densification (ED) with acceptable mass loss. Thermogravimetric analysis was employed to elucidate the thermal decomposition behaviors of JMS. By comparison with the torrefaction of Jatropha seed residue after mechanical oil extraction by screw pressing only (namely, JMET), the results indicated that the ED of the torrefaction of JMS yielding the torrefied product JMST (two-stage product) was higher than that of the torrefaction of JME giving the torrefied product JMET (single-stage product). Further, it was found that JMET contained some tar, which was attributed to a thermal reaction in the residual oil in JME during torrefaction. The tar/oil content of JMET was about 1.0–1.8 wt.% in the determined optimal conditions. Thus, the enhanced recovery of the residual oil is advantageous not only because it allows obtaining more oil from Jatropha seed residue with a positive net energy gain but also because it prevents the formation of tar in torrefied biomass products.

Highlights

Building a global energy sector with biomass crops is highly recognized as a sustainable and economically viable pathway for reaching net-zero emission [1]
The proximate analysis of JME and JMS was performed, and the results were compared in this study
The torrefaction performance at different Tr and tr was investigated for de-oiled pressed cakes of Jatropha seeds following a two-stage sequential process consisting of mechanical screw pressing and solvent extraction using n-hexane

Summary

Introduction

Building a global energy sector with biomass crops is highly recognized as a sustainable and economically viable pathway for reaching net-zero emission [1]. Among various types of biomass energy feedstock, non-food or second-generation energy crops have the potential to provide benefits such as consuming waste residues, making use of abandoned land, and promoting rural development [2,3,4]. Jatropha curcas L. is a non-edible oil plant that has spread abundantly in many tropical and sub-tropical regions throughout. Achten et al [6] pointed out that Jatropha can be favorably considered as a sustainable oil plant with respect to its environmental impact and some socioeconomic issues as long as Jatropha is cultivated on wastelands or degraded lands. The oil content of Jatropha seed and seed kernel ranges from 20% to 60% and 40%. The de-oiled residue of Jatropha seed (denoted as J-cake), whose oil content is less than 10%

Methods

Results

Conclusion