Under what circumstances can it be preliminarily determined that the return oil contains water?

Check whether there are any abnormalities in the water level of the return tank

The primary line is evacuated, and the distillation temperature in the primary line decreases

This post was last edited by Lao Wu Set on 2021-6-21 23:08. The decrease in the top temperature and distillation outlet temperature is based on theoretical analysis; in actual operation, the drop in the top temperature occurs later and to a limited extent. Oil returning with water carries fresh water directly to the top of the tower; geometric vaporization causes the tower pressure to rise rapidly. The most obvious and immediate signs of this are: 1. an increase in the opening degree of the pressure control at the top, 2. an increase in low-pressure steam volume, 3. an increase in the pressure at the tower’s feed inlet. The reduced inflow to the reflux tank leads to a decrease in the total amount of reflux, which in turn affects the temperature balance at the top of the tower. This weakens the impact of vaporization of water in the reflux stream on the top temperature. Using the top temperature to determine whether the reflux oil contains water requires taking many factors into account, making it an unsuitable method in practical operations.

This is a very insightful question. The volume of water vapor is 1,700 times that of liquid water; therefore, a small amount of backflow carrying water to the top of the tower can cause an increase in pressure and temperature at the top of the tower； If a large amount of water is present, it will cause an instantaneous overpressure at the top of the tower; the heavier components will be pushed downward, triggering the safety valve to activate. Meanwhile, once this surge occurs, it will lead to a rapid rise in the level at the bottom, resulting in a second surge ； At this time, diesel products will turn noticeably darker ； The turbines in coking plants can also experience surge ；