Hysys binary component distillation
Thread Content
As the title suggests, this is to simulate and calculate the bubble point and dew point of a binary mixture of benzene and toluene using Hysys. When benzene and toluene are mixed, with a pressure of 50 Kpa and a vapor phase composition set to 0, the bubble point is calculated to be 72.87 degrees Celsius. Where do the gas-phase components in that \"Component\" column come from? ? Isn’t the gas phase composition zero?
By doing this, the flow rate of the vapor phase component should be 0; the vapor phase composition at this temperature and pressure, that is, the composition in equilibrium with the liquid phase, has certain theoretical significance
May I assume that as long as the temperature is not at absolute zero, a liquid has a saturated vapor pressure regardless of how low its temperature is? And can this saturated steam be considered a gas phase?
I understand that if the temperature is below the boiling point, it can be considered that there is no vapor phase, and thus almost no vapor pressure. It seems you don’t have a clear understanding of the concepts of bubble point and dew point; you may refer to Principles of Chemical Engineering and Chemical Engineering Thermodynamics. Bubble formation temperature: At a constant pressure, the temperature is increased gradually from a low value (supercooled state); this is the temperature at which the first bubble appears ； Dew point temperature: At a constant pressure, it is the temperature at which the first drop of liquid appears as the temperature is gradually reduced from a high temperature (superheated state).
As long as it is as low as absolute zero, molecules still exhibit thermal motion. There is also vapor present on the surface of the supercooled liquid. Although rare, they still exist. By this logic, solids also have a saturated vapor pressure, just like the sublimation of iodine. It’s just that the vapor pressure of the supercooled liquid has not reached saturation, is my understanding correct?