FAQ on Tower Basics 23---What are the abnormal operating conditions of a tower?

This post was last edited by SuperFree2316 on 2011-3-24 at 08:30. Reference answer: Liquid droplet entrainment: For a given liquid flow rate, the higher the gas velocity, the greater the entrainment of liquid droplets, and the thicker the liquid layer on the tray. An increase in the liquid layer thickness is equivalent to a decrease in the spacing between trays, which further enhances the effect of liquid droplet entrainment. Therefore, when the gas velocity reaches a certain value, a vicious cycle occurs on the tray: the liquid layer keeps getting thicker without reaching equilibrium, and eventually the liquid fills the entire tower and overflows out with the gas. This phenomenon is known as liquid droplet entrainment. Overflowing liquid droplets: Liquid droplets that occur due to limitations in the capacity of the downcomer are called overflowing liquid droplets. A high tray pressure drop is usually the main cause of a high liquid level in the downcomer. As a result, trays with high pressure drops are more prone to overflowing liquid droplets; it can thus be seen that too high a gas velocity can also lead to this issue. In addition, a sudden increase in the resistance of the downcomer in a particular tray within the tower (such as blockage) can also cause overflowing liquid droplets. Liquid leakage: When the gas flow velocity is low, some of the liquid on the tray falls directly through the sieve holes. This phenomenon is known as liquid leakage. Apart from structural factors of the tray, gas velocity is the main factor determining whether liquid leakage will occur on a tray.

This post was last edited by SuperFree2316 on 2011-3-24 08:31. The tower exhibits the following abnormal phenomena: Liquid droplet entrainment: For a certain liquid flow rate, the higher the gas velocity, the greater the entrainment of liquid droplets, and the thicker the liquid layer on the tray. An increase in the liquid layer thickness is equivalent to a decrease in the plate spacing, which has a greater impact on the amount of liquid droplets entrained. Therefore, when the gas velocity reaches a certain value, a vicious cycle occurs on the tower trays: the liquid layer on these trays keeps thickening and no equilibrium is achieved; ultimately, the liquid fills the entire tower and overflows out with the gas. This phenomenon is known as liquid droplet entrainment. Overflow foam: The foam that occurs due to limitations in the capacity of the downcomer is called overflow foam. An excessive plate voltage drop is usually the main cause of a too high liquid level in the downcomer. Therefore, trays with a high plate pressure drop are more prone to overflow foam; it can be seen that an excessive gas velocity can also cause overflow foam. Furthermore, a sharp increase in the downcomer resistance of a certain tray inside the tower (such as blockage) can also cause overflow foam. Leakage: When the gas flow rate is low, some of the liquid on the tray falls directly through the sieve holes; this phenomenon is known as leakage. Apart from the structural factors of the tray, gas velocity is the main factor determining whether a tray will experience leakage.

Leakage, flooding, mist entrainment, bubble entrainment.

Leakage, flooding, mist entrainment, bubble entrainment

Entrained foam, overflow foam, leakage foam

Severe leakage, overflow, and significant mist entrainment.

Overflowing foam, entrained foam, leakage

Leakage, flooding, mist entrainment, bubble entrainment.

Leakage, flooding, mist entrainment, bubble entrainment.

This post was last edited by SuperFree2316 on 2011-3-24 08:31. Reply 1# **ple liquid overflow, tower flooding, etc