Slow pyrolysis of pistachio-waste pellets: combined phenomenological modeling with environmental, exergetic, and energetic analysis (3-E)

• Published in: Biomass conversion and biorefinery Vol. 14; no. 8; pp. 9197 - 9215
• Main Authors: Zalazar-Garcia, Daniela, Fernandez, Anabel, Cavaliere, Lucas, Deng, Yimin, Soria, José, Rodriguez, Rosa, Mazza, Germán
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2024; Springer Nature B.V
• Subjects: Biotechnology; Dimensionless analysis; Dimensionless numbers; Energy; Energy value; Environment models; Exergy; Heating rate; Numerical models; Original Article; Pellets; Pyrolysis; Renewable and Green Energy; Thermogravimetric analysis; Weight loss measurement; Slow pyrolysis model; 3-E analysis; Bio-waste pellet; Life Cycle Assessment; Phenomenological modeling
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-022-03232-3

Slow pyrolysis of a pellet of pistachio waste was studied using a macro-thermogravimetric analysis. Experiments were conducted at different heating rates (5, 10, and 15 K/min), measuring the evolution of mass weight loss and CO release. Based on a dimensionless number analysis, a numerical model was formulated, comprising heat and mass balances. A kinetic expression for the release of CO was proposed. Additionally, a 3-E (environmental, exergetic, and energetic) analysis for the processing of 20 kg/h of bio-waste (case study) was applied. Experimental results showed that biochar and gas yields decreased with an increase in the heating rate (43 to 36% and 28 to 24%, respectively), while the bio-oil yield increased (29 to 40%). The slow pyrolysis model presented a good agreement with experimental results of weight loss. Furthermore, a comparison with the contracting volume model showed that internal heat transport should control the global process. The proposed kinetic model for CO release showed a good fit to experimental data, where activation energy values were 29.88 (5 K/min), 17.44 (10 K/min), and 28.79 kJ/mol (15 K/min). Finally, from the 3-E analysis and the experimental results, it can be suggested that an increase in the heating rate resulted in a higher pyrolysis exergetic efficiency (70%). It is due to an increase in the bio-oil yield with high-energy content.