Mass transfer in three-phase reactive crystallization
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Kemian tekniikan korkeakoulu |
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KE-42
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Language
en
Pages
84
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Abstract
Three-phase reactive crystallization is a multi-step process which involves particles dissolution, gas absorption and precipitation. The purpose of this work is development and comparison of two kind of models for three-phase reactive crystallization. In order to do this, different models for gas absorption and precipitation were coupled with a only dissolution model. The models were compared by their implementation on MATLAB and simulating several experimental conditions from the literature in which CaCO3 and MgCO3 precipitation was operated in Ca(OH)2 –H2O-CO2 and Mg(OH)2 –H2O-CO2 systems respectively. In the first simplified model the reactions and precipitation in the film surrounding the gas-liquid interface were assumed to be negligible while in the second kind of model the phenomena occurring in the film were taken into account. The results obtained showed that the significance of the reactions and precipitation in the liquid film depends on some operational conditions such as the mass transfer resistance and the molar fraction of CO2 in the gas fed into the system. In particular in operational conditions in which a high mass transfer resistance is combined with a low concentration of CO2 in the inlet gas, the reaction and precipitation phenomena were predicted to occur mainly in the film. In this case the use of the simplified model significantly under-estimated of the mass transfer rate.Description
Supervisor
Alopaeus, VilleThesis advisor
Jakobsson, KajZhao, Wenli