What’s wrong with this distillation tower?
Thread Content
This unit features a distillation column; the feed composition contains 4.5% of C10+ components, with the remaining components being mixed C5 hydrocarbons, which are taken off as side products. Recently, the pressure difference has been fluctuating (within the range of 53–59 KPa), resulting in a high level of Reorganization components at the top of the tower. It is initially suspected to be flooding; the problem persisted even after stopping the tower and feeding it again. The top reflux rate dropped from 20 t/h to 6 t/h, and operation was still possible, with no change in pressure difference. The quality of the side-product met the requirements more or less, but the content of key components at the top of the tower was high. What is most puzzling is that the amount of steam used at the bottom of the tower remained unchanged – isn’t this a violation of energy conservation? Need advice?
Is it possible to have water in it? If a small amount of water is present, for the C-10 component at the bottom of the tower, the operating temperature must be above the boiling point of water, while the temperature at the top of the tower is far below that boiling point. This small amount of water moves up and down within the tower but cannot be removed, resulting in fluctuations in tower pressure. The presence of water also leads to the entrainment of foam, increasing the concentration of heavier components at the top of the tower. If the hypothesis is correct, it is recommended to stop feeding material, bring the temperature inside the tower down to room temperature, remove the substandard products from the bottom of the tower and send them to the storage area for sedimentation and dehydration, before resuming feeding. The reflux tank is also checked for water to determine whether there are internal leaks in the reboiler or cooler.
This tower had leaks before, but it’s different from now; upon careful inspection, no significant increase in water content was detected
Previously, gas-phase feeding was used; during the period of instability, the feeding temperature was reduced, but the situation still did not improve
Analyze whether there have been any changes in the raw material components? If the changes are minor, then under the same feed conditions, restoring the original normal operating conditions should result in satisfactory performance. If that still doesn’t work, then check whether the tower is clogged or leaking. If the composition of the raw materials changes significantly, then adjust the position of the feed plate or the reflux rate, as well as the yield from the bottom of the tower, accordingly.
{:2_39:}Plate tower? You can check your tower; this issue might be related to your hardware. Fluctuations in the pressure difference within the tower are not only caused by flooding but also by blockages in some of the vaporization holes. Moreover, it’s impossible for there to be an imbalance in heat – you must have made a calculation error. If the total amount of heat input remains unchanged, then the total amount of condensation will also remain unchanged. It’s just that as the composition of the material changes, so does its enthalpy; one cannot rely solely on the temperatures at various measurement points
The tower is clogged, resulting in insufficient contact between the rising gas and the reflux liquid, so that the heavier components cannot be washed away.
Were a few layers of the tray flipped over? Stop work to check it
In such cases, we generally consider the possibility that there is a problem with the hardware of the tower. We are currently using a packed tower, and when the packing becomes partially blocked, this situation occurs. The uneven energy exchange between the vaporized material resulting from heating and the liquid material leads to fluctuations in vacuum pressure, which in turn affects the distillation efficiency of the distillation tower. Our filler towers here are shut down regularly for maintenance to check the condition inside them