Reasons for low pressure drop in packed towers
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There is a high-pressure packed tower with three sections of packing; the feed is divided into two streams at the middle and lower sections. The pressure difference across the tower is low; as a result, the product at the bottom of the tower contains light components, while the product at the top contains heavy components. The heating temperature at the bottom of the tower is high, and there is almost no temperature difference between the packing in the middle and upper sections of the tower and the product at the top. Is this phenomenon caused by an uneven initial liquid phase distribution, resulting in severe channeling or wall flow within the packing layer? I hope kind sea friends can help.
In the case of a high-purity separation tower, the temperature difference from the top to the upper section is usually very small, so there’s no need to make a big deal out of it. However, based on the description provided by the poster, there are light components at the bottom of the tower and heavy components at the top; it is clear that the separation is not complete. It is very likely that an uneven distribution of the liquid phase inside leads to insufficient gas-liquid contact, resulting in low efficiency.
Thank you to the moderator for the reply. Currently, we ensure mass transfer between the gas and liquid phases by increasing the reflux rate, but this in turn increases the heating required in the bottom of the tower. Moreover, its operational flexibility is not as good as before.
It seems like the liquid holding capacity is insufficient (the return flow rate is low)
Thank you to the friend who replied above. The issue here is an imbalance between gas and liquid inside the tower, which leads to a decrease in the efficiency of gas-liquid mass transfer. To address this, one can increase the reflux rate in order to raise the pressure difference; however, this approach increases the heating required in the tower bottom, resulting in a lower temperature on the sensitive plates. Did severe channeling or wall flow occur inside the tower?
Have any of you sailors encountered this situation?
It’s best to check the design values of all your parameters, trying not to deviate too much from them. First, adjust it to the design value; if there are still problems, it is possible that there is an issue with the internal components of the tower.
How should it be adjusted in the case of channel flow or wall flow?
Original poster, go down and click to reply so that others can see your response. You see, no one has responded to you because they didn’t receive any notifications. First, adjust your tower to the load specified in the design; if it still fails to meet the requirements under those design conditions, then you will have to consider the issues related to the internal components
Has the owner installed new equipment, or carried out major repairs and replaced the internal components and packing of the tower? Was it functioning properly before? The poster wants to control the Reconstituted components at the top of the tower; the separation efficiency of the packed tower using light components at the bottom is limited. Additionally, it is possible that the composition of the feed has changed.
What’s the use of increasing the return flow if there’s channeling or wall flow?