Torrefaction and Process Energy Budget Analysis of Powdered, De‐oiled, and In Situ Transesterified Flaxseed Cakes for Energy Generation

Abstract

Edible vegetable oil seeds are used to produce oil for human consumption and inedible vegetable oil seeds are used to produce biofuels; the residue cakes from the extraction process contain significant energy that can be utilised. This study is a continuation of previous work on oil extraction from flaxseed to produce biodiesel; herein, the residue cake from flaxseed was studied. Three different types of samples (powdered seeds, de‐oiled cake, and in situ transesterified cake of flaxseed) were torrefied (through slow pyrolysis), and the sample properties were characterized. The higher heating value (HHV=36.01±0.36 MJ kg−1) and bulk density (0.33±0.01 g cm−3) of the powdered seeds are higher compared to the other two samples (i.e. de‐oiled cake and in situ transesterified cake). The torrefied biomass was light weight losing its mechanical strength on treatment, making it easier to grind. It was observed that the biomass torrefied at 300 °C had a higher fraction of particles between sieve sizes (between 2.0 and 0.063 mm) compared to the biomass torrefied at 200 °C. The sieve sizes between 0.5 and 0.063 mm showed that more particles of the torrefied biomass treated at 300 °C were collected compared to that torrefied at 200 °C. Due to the loss of hydrogen and oxygen content and the removal of water, the carbon content in the torrefied biomass increased by 25.52, 24.51, and 22.69 % for the powdered seeds, de‐oiled cake, and in situ cake samples, respectively. The powdered seeds had a higher carbon and hydrogen content compared to the de‐oiled and in situ transesterified flaxseed cakes because the powdered seeds contained fatty acids. The powdered seeds had a higher concentration of CO2 gas liberated during treatment compared to the de‐oiled and in situ transesterified cakes. This was attributed to the powdered seeds having a higher concentration of volatile hydrocarbons and a lower ash content. It was observed that the energy ratios were reduced with respect to increasing temperature whereas the highest energy ratios were found for the powdered seeds.

Mild Pyrolysis of Manually Pressed and Liquid Nitrogen Treated De‐Lipid Cake of Nannochloropsis Oculata for Bioenergy Utilisation

“…The surface morphology showed cracks appearing on the surface due to shrinking effects with the removal of moisture and other low molecular weight compounds. This is attributed to the evaporation of water and reduction in carbon and hydrogen content from the biomass with respect to increase in temperature (from 200 to 300 °C for 30 min) …”

“…This is attributed to the evaporation of water and reduction in carbon and hydrogen content from the biomass with respect to increase in temperature (from 200 to 300°C for 30 min). [24]…”

Potential of using microalgae to sequester carbon dioxide and processing to bioproducts

“…61 The algal cell wall gets disrupted due to fluid shear, turbulence, shock velocity, and cavitation. Other mechanical pretreatment methods include ultrasound, 62 microwave, 63 glass beads, 61,64 and electric pulse. 65 Biological pretreatments are carried out using individual or combination of commercial carbohydrate-active enzymes (CAZymes) such as cellulases (endo-exo-glucanases, β-glucosidase); hemicellulase (xylanase, pectinase); amylases, amyloglucosidase and other enzymes (chitinase and sulfatase) produced using fungus and bacteria in varying concentration.…”

Integration of Biomass Torrefaction and Gasification based on Biomass Classification: A Review

“…4) Although there are many constituents in solid waste that can be used as raw materials for torrefaction, the fledgling cooperation between independent producers and suppliers in the market is a challenge in the development of torrefied biomass products, as biomass resource utilization is a huge industrial chain. [ 155 ] For instance, there is not yet a complete chain of cooperation among biomass suppliers, producers, investors, and potential users in Malaysia, resulting in a huge waste of resources. [ 156 ] Therefore, it is necessary for government departments to take the lead in establishing solid waste collection centers to facilitate and reduce collection time and logistics costs.…”