Issues regarding the top temperature of the fractionation tower and the dry point of crude gasoline
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The top temperature of the fractionation tower is controlled at 105 degrees; why is the dry point of the crude gasoline around 200 degrees? How can a 200-degree fraction be vaporized at a temperature of 105 degrees below zero? Is it related to stress? Why not 105 as the dry point? Could that expert please explain it?
The dry point of crude gasoline is the dew point temperature at its own vapor pressure. Dryness is related to pressure
This post was last edited by fengdingwen on 2010-4-22 08:20. Since the side products are drawn off in liquid form, the distillation temperatures of each side stream in the fractionation tower correspond to the bubble point temperature of that side product under the vapor pressure of the oil and gas at that location. Since the product at the top of the fractionation tower is withdrawn as a vapor phase, the top temperature is the dew point temperature of the top product under the vapor pressure of the overhead gas. The bubble point and dew point temperatures are related to the mixture composition and system pressure.
The dry point of the gasoline at the top of the tower is related to temperature and pressure; to maintain a suitable dry point for the gasoline there, the pressure needs to be lower than normal.