AONDOAKAA, EPHRAIM AHILE and Covenant University, Theses Masters (2024) SIMULATION OF CARBOHYDRATE PRODUCTION USING CO2 CAPTURED FROM FLUE GASES WITH ASPEN PLUS SIMULATION TOOL. Masters thesis, Covenant University.
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Abstract
The Earth’s global temperature requires urgent attention in order to reduce it to well below 2 °C, as stipulated by the Paris Agreement. This research models a process for capturing carbon dioxide (CO2) from flue gases, and producing carbohydrates using post-combustion captured, adaptable to existing plants. A feed flue gas basis of 10 tons per day (300 °C, 10 bar) was considered. The capturing technique modelled achieved a CO2 recovery of 96 % and a CO2 purity of 93 %, meeting regulatory targets above 90 %. Based on thermodynamic equilibrium and phase equilibria calculations, the Aspen simulation of the carbon capture process via pressure swing adsorption revealed an energy requirement of 0.163 MJ per kg of CO2, compared to 0.7 MJ per kg CO2 reported by Nikolaidis, Kikkinides, and Georgiadis (2017). Conventional monoethanolamine (MEA) absorption processes for CO2 capture typically require over 4 MJ per kg CO2 (Ferrara et al., 2017). The process utilised a pressure swing adsorber (PSA) for CO2 capture, followed by the direct conversion of CO2 to saccharides (glucose, galactose, and fructose) in an artificial photosynthesis reactor. Varying the feed water flow rate from 20 kg/hr to 50 kg/hr reduced the glucose to galactose mass selectivity from 75:100 to 66:100. Varying the pressure of the artificial photosynthesis reactor (APR) from 0 to 40 bar increased the glucose to galactose mass selectivity from 72:100 to 78:100. Varying the reactor temperature from 0 °C to 320 °C decreased glucose yield from 33.1527 kg/hr to 1.6516 kg/hr, while galactose yield increased from 0.0045 kg/hr to 31.5056 kg/hr. Optimisation revealed a maximum glucose yield of 0.6824 kg per kg CO2 (1:5.9998 molar basis), with an efficiency of 99.996 % at 0 °C, 31.741 bar, and 40 kg/hr water flow rate. The artificial photosynthesis reactor required 17,255.9375 kJ per kg of glucose (3,108.7607 kJ/mol), efficient compared to the theoretical standard enthalpy of formation, 2,802.5 kJ/mol. Optimising galactose yield demonstrated 0.6797 kg per kg CO2 (1:6.0187 molar basis), comparable to the theoretical stoichiometry of 1:6, at 500 °C, 17.7763 bar, and 44.857 kg/hr water flow rate. The reactor required 20,454.6394 kJ per kg of galactose (3,681.8351 kJ/mol). The condensation reactor predominantly produced sucrose (31.4993 kg/hr), regardless of conditions, indicating thermodynamic favourability. Polysaccharide synthesis was infeasible due to the non-convergence of simulations, likely due to the absence of biological catalysts necessary for complex polymerisation reactions. This research highlights the potential and limitations of CO2 conversion processes to valuable biochemicals, providing a basis for future experimental investigations.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Carbon dioxide, Simulation, Carbohydrates, Flue Gases, Monosaccharides, disaccharides, Polysaccharides, Technologies, Aspen Plus, Optimisation, Sensitivity Analysis, Artificial Photosynthesis, Captured. |
| Subjects: | Q Science > QD Chemistry T Technology > TA Engineering (General). Civil engineering (General) T Technology > TP Chemical technology |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Chemistry |
| Depositing User: | ORIGBOEYEGHA |
| Date Deposited: | 16 Sep 2024 16:10 |
| Last Modified: | 16 Sep 2024 16:10 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/18417 |
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