Problems with the liquefied gas tank at the stabilizer tower top
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The pressure at the top of the stabilizer is very high and doesn’t drop quickly, but the liquid level in the liquefied gas tank keeps falling. What actions can be taken to ensure that the liquefied gas pump does not get empty?
This post was last edited by jbcyf on 2011-11-15 at 11:13. It’s possible that the liquefied gas has vaporized; pay attention to the temperature of the liquefied gas as it enters the tank and the volume of dry gas exiting from the top of the tank. If the temperature is high, the dry gas volume is large and it contains a significant amount of C3 and C4, then the load on the top of the tower (the distillation section) should be reduced – for example, by lowering the reflux temperature, reducing the reflux rate, and decreasing the proportion of dry gas in the feed to the stabilizer tower.
Lowering the temperature may result in poor desorption; for liquefied gas containing carbon, release the non-condensable gases to relieve pressure, and try reducing the amount of cold reflux.
If the cooling effect is sufficient and the pressure drop does not occur, it’s C1 or C2; in such cases, the non-condensable gas has to be released. To maintain the liquid level in the return tank, the only option is to enhance the cooling effect. Lower the temperature of the liquid hydrocarbon; please take this into consideration!
Cooling at the tower top; non-condensable gas is released from the reflux tank
Is it a problem with the regulation of the hot and cold circuits? In other words, too much flow occurs in the hot circuit, resulting in less flow in the cold circuit; this leads to an increase in pressure. Since liquefied gas exists in a gaseous state inside the tank, the liquid level drops rapidly
First, reduce the reflux rate a bit—then make some adjustments to the temperature of the liquefied gas after it enters the tank—that should do it. If you try to lower the temperature at the top of the tower by increasing the reflux rate, that’s definitely incorrect; when the reflux rate is too high, more vaporization occurs at the top of the tower, and as a result, the pressure cannot be reduced. Lowering the temperature of the liquefied gas after it enters the tank is a very effective approach
High pressure at the top of the tower – resulting in high natural pressure inside the tank – the liquefied gas is compressed – hence the liquid level reading is low