Cryogenic Distillation of Carbon-Dioxide – Low Temperature Separation Method

The cryogenic distillation of carbon-dioxide, also known as the low temperature separation method, uses de-sublimation/frost separation to remove CO₂ from flue gases, it has the inherent advantage of being compact and non-corrosive. De-sublimation/frost separation can be realized directly from the gas state at pressures substantially below the triple point, for instance the de-sublimation pressure at 195K is 0.1MPa. Cryogenic distillation can be performed at relatively low pressures and hence is safer and energy efficient as compared to other technologies.

The prime focus of this work is to numerically investigate this efficient means of phase transition carbon capture using Hertz-Knudsen model. The Hertz-Knudsen model available in Ansys Fluent can account for wall evaporation or condensation and has been used for performing the present analysis. The phase transition from gaseous to solid state has been captured using a judicious combination of models that mimic the actual conditions. The results obtained compare quite well with available experimental data. There exists a direct correlation between the volumetric flow rate of flue gas and the efficiency of CO₂ removal. The efficiency of CO₂ removal increases with lower flow rates, and this agrees with the past findings from literature.