Enhancement of fuel characteristics of rice husk via torrefaction process

Abstract

Torrefaction, is a pretreatment process in the conversion of various biomass feedstocks into an efficient solid fuel. In the present research, rice husk was torrefied at 200°C, 250°C, and 300°C for 10, 30, 90, and 150 minutes under a non-oxidative environment. The energy yield and mass yield of torrefied solid residues ranged from 51.3% to 96.8%, and 49.1% to 95.1%, respectively, under torrefaction conditions. Increasing the residence time and temperature of thermal treatment causes a rise in carbon content from 32.45% to 48.5%, and raises the calorific value from 16.48 MJ/kg to 19.82 MJ/kg. The torrefaction process also reduced the swelling tendency of the biomass in water from its initial value of 308% to 92% only. Various other characterizations including Fourier transform infrared radiation, thermogravimetric analysis (TGA) and scanning electron microscopy were performed to analyze the structural and textural aspects of torrefied biomass. The TGA and derivative thermogravimetric analysis curves indicated that torrefaction affected the hemicellulose fraction of biomass significantly. The surface morphology of thermolyzed samples revealed the rupture of the surface induced by the torrefaction process. Overall, the torrefaction process has not only improved the fuel characteristics of the rice husk but also enhanced its hydrophobicity.

Oxidative Torrefaction of Sunflower Husk Pellets in the Kaolin Layer

“…As a rule, under more severe conditions of torrefaction, the structure of torrefied biomass increasingly resembles the structure of common solid fuel (for example, the hydrocarbon structure of coal), acquiring also the hydrophobic properties typical of nonpolar hydrocarbons [22]. This result is consistent with Aslam et al [51], where the hydrophobicity of torrefied rice husks was investigated at different temperatures (200, 250, 300 °C), and a decrease in the biomass tendency to swell in water was observed with an increase in torrefaction temperature from its initial value of 308% to 92%.…”

Thermogravimetric studies on co-pyrolysis of raw/torrefied biomass and coal blends

“…These include high moisture content, low heating values and energy density levels, hygroscopic character, significant smoke emissions during combustion and uneven physicochemical properties due to the diversity of biomass sources (Chen et al, 2012). These issues lead to challenges in the transportation, storage and use of raw biomass and, as a result, some research work has been conducted to resolve such issues through torrefaction (Aslam et al, 2019).…”

Impacts of non-oxidative torrefaction conditions on the fuel properties of indigenous biomass (bagasse)

“…The FTIR spectra of the raw and torrefied biomass are provided in Figure 4. To explain some important structural changes, some well-defined peaks were labeled and assigned to different functional groups as follow (Pandey, 2003; Popescu et al, 2010): 3300–3500 cm −1 (a) for the vibration of O-H bond (Kanwal et al, 2019; Liu et al, 2008), 2900 cm −1 (b) for C-H stretching in lignin (; Aslam et al, 2019; Xiao et al, 2015), 1750–1800 cm −1 (c) for unconjugated C=O valence vibration of aromatic rings (Zheng et al, 2014), 1400–1350 (d) for C-H bond vibrations and 1000 cm −1 (e) for C-O, C=C, C-C-O groups present in cellulose, hemicellulose and lignin (Chang et al, 2012; Yang et al, 2007). From Figure 4, the obvious changes in the IR spectrum of the torrefied bagasse can be noticed when compared with the raw biomass and a decrease in the intensity of all the peaks was observed as the process conditions were intensified.…”

“…As Pakistan generates 79% of its total energy from fossil fuels, the energy production cost is very high as most of the fuel is imported and at the same time, the country is facing an energy crisis. The contribution of RE resources in Pakistan’s energy mix is negligible (Aslam et al, 2019). In 2010–2011, Pakistan produced 6.4 × 10 10 kg of sugarcane, generating waste of around 5.8 × 10 9 kg (Naqvi et al, 2018).…”