A master thesis from Aalborg University
Variable screening of pyrolysis of composted Cattle Manure in a semi-batch reactor: Thermochemical degradation of biomass
[Variabelscreening af pyrolyse af komposteret kvæggylle i en semi-batch reaktor]
Author(s)
Term
4. term
Education
Publication year
2025
Submitted on
2025-08-22
Pages
122 pages
Abstract
Energy consumption is increasing globally; fossil fuel resources are diminishing and polluting. However, substituting fossil fuels is difficult due to their participation in almost all facets of human existence in one form or another. It may be possible to substitute some of the fossil fuel demand by utilizing biomass. Pyrolysis is a method of thermochemical degradation in an inert atmosphere at elevated temperatures, that produces biochar, biooil, and pyrolytic gas. These products have numerous applications, including fertilizers, value added chemicals and fuels. Composting cattle manure may be used to reduce the water content of the cattle manure, making it feasible to perform pyrolysis on this biomass. The effects of temperature, hold time and the use of CO2 as the atmosphere was investigated via a variable screening design for numerous different analyses of the biochar and biooil. Increasing the temperature changes the chemical composition of both the biochar and the biooil, as well as the yields of the different product phases. Notably the biochar carbon content increases, leading to an increased temperature for thermal mass loss, as well as a higher gross calorific value. The biooil composition changes dramatically in relation to the temperature, leading to more phenolic oil, due to enhanced lignin decomposition. The biooil composition is also affected by the atmosphere, as a longer hold time in CO2 increases the content of aliphatic and cyclic content, while decreasing the aromatic content. This effect is not seen when the process is run in a nitrogen atmosphere. From PCA, it is possible to determine that 39.76% of the total variance is due to the variation of the temperature level. The pyrolysis products should not be applied as fuels, due to the immense energy costs of pyrolysis, but utilizing it as a fertilizer may be feasible based off the heavy metal contents.
Keywords
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