Gasification of lipid-extracted algae and fucoidan- extracted seaweeds for syngas production
Lipid-extracted algae (LEA) are the by-products of algal lipid extraction that are used in many applications, for instance, biogas generation, ethanol manufacturing, animal feed, fertilizer, methane and as hydrogen fuel. LEA are less utilized in gasification and fucoidan-extracted seaweed r...
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Format: | Thesis |
Language: | English |
Published: |
2019
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Subjects: | |
Online Access: | http://psasir.upm.edu.my/id/eprint/84173/1/FK%202019%20134%20-%20ir.pdf http://psasir.upm.edu.my/id/eprint/84173/ |
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Summary: | Lipid-extracted algae (LEA) are the by-products of algal lipid extraction that are used in many
applications, for instance, biogas generation, ethanol manufacturing, animal feed, fertilizer,
methane and as hydrogen fuel. LEA are less utilized in gasification and fucoidan-extracted
seaweed residue is usually disposed after the extraction, hence, this study employed
these algae residues via gasification, which is a thermochemical conversion technology
of biomass into synthesis gas (syngas) to minimize the underutilization issue. The potential
of lipid-extracted Nannochloropsis gaditana algae (LEA) and fucoidan-extracted algae that
consist of mixture of Sargassum sp., Padina sp., and Enteromorpha sp. algae for synthesis gas
production via gasification is investigated in this study. The effects of varying different process
parameters; temperature and biomass loading on the synthesis gas composition, mainly H2
and CO yields are evaluated. The characterization of the samples were carried out in Fourier
Transform Infra-Red (FTIR), Thermogravimetric analysis (TGA), elemental analysis and bomb
calorimetry test. Kinetics study of both algae residues are carried out using
Kissinger-Akahira-Sunose (KAS) and Flynn-Wall- Ozawa (FWO) models that showed the degradation
behaviour of the algae residues at high temperature, as indicated by the activation energy (Ea) at
different degradation (α), proximate analysis and average degradation rate (AR).
The gasification experiments were performed at different process parameters; temperature (600,
700, 800, 900 and 1000 ᵒC), sample loading (0.3, 0.4, 0.5, 0.6 and 0.7 g) and equivalence
ratio (ER) (0.1, 0.2, 0.3, 0.4 and 0.5) at fixed holding time (30 minutes). Yield of H2 and CO were
found to increase with temperature due to the effect of oxidation, water- gas, water-gas shift and
Bouduard reactions. Increasing ER value decreased H2 and CO yields due to the boosted oxidation of
carbon that produced more CO2. Sample loading increment resulted in increment of H2 yield
and decrement in CO yield, however, it did not significantly affect the syngas
compositions, since it did not involve in the gasification mechanism. The same phenomena were
observed for the data obtained from the simulation. Experimental gasification via Central Composite
Design (CCD) approach revealed that optimized conditions for both samples gasification were 718.77℃, 0.3 g loading and 0.24 ER value and 766.99℃, 0.7g loading
and 0.1 ER value for LEA and seaweeds residue, respectively. At this conditions, the
yield of H2 and CO were 36.38 mol% and 13.28mol% respectively, for LEA and 47.99 mol% and 26.05
mol% respectively, for seaweeds residue. The experimental H2 and CO yields were largely deviated
from the simulation data, as observed from the root mean square error (RMSE) values. Thus,
enhancements of the experimental facilities and limitations of Aspen Plus simulation could
be done to
improve the RMSE values of the largely deviated data. |
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