The Wetted Wall cell is used to measure intrinsic parameters relating to absorption processes such as reaction kinetics, mass transfer coefficients and so on.
It has mainly been used to study solvents for CO2 capture, such as MEA, MDEA, MDEA with enzymes, potassium carbonate and ammonia.
Detailed description
The gas comes from N2 and CO2 bottles. The flow and the pressure of the gases sent to the chamber are controlled by the mass flow controllers. The gas is then saturated with water, and reaches the reaction chamber that consists of a glass tube that can resist a pressure up to 10 bars.
The gas outlet, on the top of the chamber, comprises a needle valve to reduce the pressure to atmospheric. The gas passes through an acid wash section in order to remove the ammonia present in the gas phase and through a condenser in order to remove the water.
The concentration of carbon dioxide is then measured with a gas analyzer and sent to the fume hood. An alternative would be to measure the gas before it is condensed and washed and by correcting the actual value of the CO2 pressure by evaluating the pressure of ammonia and water using the thermodynamic model.
When MEA is used, it can be assumed that the amount of MEA in the gas phase is negligible.
The liquid is pumped from a stainless steel tank to the chamber, after it passes through the oil tank to control its temperature.
It flows though the stainless steel tube and on its surface as a homogeneous film where it can react with the gas. The liquid leaves the chamber by its bottom, and is transferred back to the liquid tank. Therefore, the liquid is used in a closed loop.
It is assumed that the CO2 loading of the solvent does not significantly change during an experiment.
A water cooling bath is used to control the temperature. The water is circulated around the chamber to maintain a constant temperature. The experiments will be conducted in the temperature range of 0-80 °C.
The liquid reactor is about 2 liters and the main chamber about 0.25 liters.
A schematic of the wetted wall column setup.
Publications
Arne Gladis, Maria T. Gundersen, Philip L. Fosbøl, John M. Woodley, Nicolas von Solms, “Influence of temperature and solvent concentration on the kinetics of the enzyme carbonic anhydrase in carbon capture technology,” Chemical Engineering Journal 309 (2017) 772–786