2 replies to this topic

[Witchchild]

Hi, I have a gas mixture entering the distillation column as a liquid  bellow  critical temperatures. However the temperature of the column at the bottom increases so that one of the components is now above the pure gas's critical temperature. Does this mean the compressed component which has entered as a liquid will revert back to being a gas at this temperature since you can't compress a gas above its critical temperature or is there still a liquid phase? If so, what will be density of the liquid? Is it the same density as the vapor phase or is there just no liquid phase for this component in the bottoms. The pressures of the column are bellow critical pressure.

[Saml]

Gases dissolve in liquids (you can use Henry law for low concentration,or more sophysticated models at higher concentration).

 

This is situation similar to the one in a boiler feed water deareator, where you eliminate the air (above critical point) dissolved in water.

Also you can have carbon dioxide above critical temperature dissolved in water.

 

For density you have to use a rule of mixing. There are several. from simple to more complex.

[latexman]

The feed tray material and energy balance with appropriate choice of physical property, equilibrium, and thermodynamic models for the components (i.e. simulation) will give you an estimate of what will happen.