Could someone expert help resolve this doubt?
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This post was last edited by Green Lotus on 2018-5-5 10:53. Why does the vapor from the top of the distillation tower enter from the bottom of the reflux tank? What are the benefits of doing this?
Generally, the location of the water cooler in a distillation tower should be below the bottom of the reflux tank; you can check this on site. This arrangement is intended to ensure that the heat exchanger is filled with liquid medium, thereby enabling efficient heat exchange. So the heat exchanger is placed lower; by going upward from there, the feed can be positioned at the bottom of the reflux tank.
I agree with you; that’s exactly what the reflux tank at the top of the stabilizer is for.
I was wondering: after passing through the top condenser, the vapor at the top of the tower enters the reflux tank from the bottom of it. Isn’t it normal for it to enter the reflux tank from the top of the tank via the top condenser?
“I disagree with the statement that the location of the distillation tower’s water cooler should be below the bottom of the reflux tank; this is mainly done to ensure that the heat exchanger is filled with a liquid medium, thereby enabling efficient heat exchange. If by water cooler you mean the condenser at the top of the distillation tower, then when the location of this condenser is below that of the reflux drum, heat bypass pressure control is generally used. This approach is not intended to ensure that the condenser is filled with a liquid medium, but rather to control the pressure at the top of the tower by altering the liquid level within the condenser, thereby changing the condensation area for the gases at the tower top.
This is the thermal bypass control tower pressure. The top condenser is installed below the reflux tank, and a portion of the hot gas passes directly into the reflux tank via a bypass around the condenser. Through the action of the pressure regulator, the liquid level in the shell side of the condenser is changed, thereby altering the condensation area.
Based on your subsequent reply, your question wasn’t clearly stated. It is not the gas phase that enters from the bottom of the reflux tank, but rather the condensate from the tower top gas phase that enters from the bottom of the reflux tank.
Generally, the location of the water cooler in a distillation tower is below the bottom of the reflux tank. This is probably related to the petrochemical industry, as in many cases the location of the condenser at the top of the distillation tower is above that of the reflux tank.
My conclusion might be overgeneralizing; I’ve learned my lesson! :handshake
Because if the pressure in the distillation column is under automatic control, a regulation method using a thermal bypass for the top condenser is employed; when the pressure at the top of the column is high, the system automatically reduces the size of the thermal bypass. As a result, the difference ΔH between the liquid level in the reflux tank and that in the condenser increases, which leads to more tubes being exposed to the gas phase, increasing the amount of condensation and thereby reducing the pressure at the top of the column. This is used to regulate the tower top pressure.