How to calculate the vapor pressure at the top of a distillation column, and the dew point
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The processing volume is low; to prevent coking, a large amount of gas is supplied for the reaction, and water often enters the top circulation, resulting in substandard crude steam and diesel. It is intended to determine the dew point corresponding to a certain value by calculating the vapor pressure, in order to prevent a series of problems caused by water carried in by the top circulation (such as salt accumulation on the lower trays of the tower and poor product quality). Please help a lot! Thank you! ! ! !
The temperature of the top recirculation tower must be kept above 100 degrees to prevent salt deposition on the tray surfaces; the calculation of partial pressures is based on Dalton’s law
If water is present, the vapor pressure at the top of the tower should be the saturated vapor pressure at that temperature, which can be found by consulting a table.
Just because the temperature control in the top recirculation tower is above 100 degrees, it does not necessarily mean that no salt will form. The return tower temperature is merely a temperature point on a pipeline and does not represent the tray temperature
The overhead distillates include: dry gas, liquefied gas, gasoline, reflux, and water vapor； Its flow is measured by a meter ； The molecular weight of dry gas and liquefied gas can be determined from the analyzed composition ； The molecular weight of gasoline can be estimated at 105 ； The backflow molecular weight can be estimated at 110 ； By determining their molar fractions, the partial pressures can be calculated ； The dew point temperature can be determined by consulting a pressure-temperature chart.