Torrefaction of Solid Olive Mill Residue

Abstract

Solid olive mill residue (SOMR), a lignocellulosic material obtained from olive oil extraction, is a potential attractive source of biomass for energy generation. Although SOMR can be directly combusted, a pretreatment can reduce the oxygen and moisture contents of raw SOMR for efficient energy generation. Torrefaction is a promising thermal pretreatment method for improving fuel characteristics of raw SOMR. In this study, torrefaction characteristics of SOMR were investigated at three different torrefaction temperatures and holding times. Ultimate and proximate analysis results of torrefied SOMR were compared with dried SOMR. Results indicate that an increased torrefaction temperature and holding time can lead to a more qualified solid fuel with higher carbon content, increased higher heating value (HHV), and reduced oxygen content. Further, increased HHV and removal of volatiles are indicators of more energy-dense solid fuel obtained from SOMR. Experimental results revealed that moderately severe torrefaction conditions with holding times not exceeding 30 minutes are suitable for torrefaction of SOMR.

Torrefaction of Various Types of Biomass in Laboratory Scale, Batch-Wise Isothermal Rotary Reactor and Pilot Scale, Continuous Multi-Stage Tape Reactor

“…Study demonstrated that the content of oleic acid had influence on the carbonisation pathway, when comparing tor-refied olive waste with pathway for carbonisation of coal, which was shown at Van Krevelen's diagram [35]. Cellatoglu and Ilkan used a custom build, batch-wise operating torrefaction setup, to torrefy olive waste at the temperatures ranging between 210 and 280°C with residence times of 30 up to 120 min [36]. Study concluded that the optimum conditions for the torrefaction of olive waste would be temperature of 280°C and residence time of 30 min [36].…”

Solar Torrefaction of Solid Olive Mill Residue

“…Torrefaction studies done for various biomass studies and SOMR showed that torrefaction produces a solid fuel with reduced volatile matter and increased ash and fixed carbon content (Cellatoğlu and İlkan 2015;Chiou et al 2015). Figure 5 shows the volatile matter content of raw SOMR and sSOMR.…”

“…The authors showed that torrefaction of SOMR (or olive pomace) can be described by a single step model. Also, Chiou et al (2015), Cellatoğlu and İlkan (2015), and Benavente and Fullana (2015) investigated the changes in elemental and proximate compositions of SOMR under different torrefaction conditions (temperature and holding time). Results of the cited studies showed that torrefaction yielded solid fuel with higher carbon, ash, and fixed carbon content and less oxygen, hydrogen and volatile matter content compared to raw SOMR.…”

“…Results of the cited studies showed that torrefaction yielded solid fuel with higher carbon, ash, and fixed carbon content and less oxygen, hydrogen and volatile matter content compared to raw SOMR. Cellatoğlu and İlkan (2015) showed that rising torrefaction temperature from 210 o C to 240 o C results in a significant change in elemental composition of SOMR. Furthermore, Chiou et al (2015) showed that significant change in elemental composition occurs when temperature is raised from 230 o C to 260 o C. Consistent with studies of Chiou et al (2015) and Cellatoğlu and İlkan (2015), solar torrefaction, conducted at 250 o C, results in significant changes in elemental and proximate composition of SOMR.…”

“…SOMR is suitable for the process done in the Mediterranean region, which enjoys the abundance of solar energy. Also, SOMR is an attractive fuel for torrefaction (Cellatoğlu and İlkan 2015). In this study, solar torrefaction of SOMR was tested with a parabolic dish collector.…”