University of Twente Student Theses


Low temperature combustion kinetics of high mineral paper sludge char particles.

Iyer, Logonadhan (2022) Low temperature combustion kinetics of high mineral paper sludge char particles.

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Embargo date:23 March 2032
Abstract:A circular economy is being implemented in a number of industries in order to reduce their carbon footprint. The paper industry uses calcium carbonate (CaCO3) to enhance the whiteness of the paper. The waste stream of the paper industry is the wet paper sludge. Alucha recycles the CaCO3 in this waste stream to produce their Circular Calcium Carbonate (CCC). After drying and the pyrolysis of this waste stream, solid feeds are obtained. This solid feed contains about 80-90% minerals, 8-10% char and 5-10% volatiles remaining after the pyrolysis, which is combusted in a bubbling fluidized bed (BFB) reactor to remove of the char and volatiles from the minerals. This assignment aims to find the kinetics of the char combustion and mineral decomposition in the solid feeds. As the temperature increases, the mineral decomposition rate also increases. Hence, the bed temperature should be kept as low as possible. By doing a series of experiments with TGA and a literature review, the influence of temperature and oxygen concentration on char combustion has been studied. A MATLAB model has also been developed, which uses TGA data to determine the kinetics of char combustion and mineral decomposition in the Alucha paper sludge char particles. Several tests are carried out with the lab BFB at Alucha to validate char combustion kinetics. These tests were done to check how well the kinetics data predicts the residence time for char combustion in the BFB. Lastly, the maximum heat recovery from the BFB reactor is discussed to check the sustainability of char combustion. The heat energy that can be extracted utilizing the heat exchangers in the BFB has been studied, as well as the fraction of wet paper sludge drying heat demand that it can meet.
Item Type:Essay (Master)
Alucha, Arnhem, The Netherlands
Faculty:ET: Engineering Technology
Subject:30 exact sciences in general, 35 chemistry, 50 technical science in general
Programme:Sustainable Energy Technology MSc (60443)
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