What happens when there is an excess of steam during bottom stilling?
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What happens when there is an excess of steam during bottom stilling? For example, when distilling methanol from a mixture of methanol and water, if there is an excess of vapor, it will cause a large amount of water to be evaporated to the top of the tower, resulting in an increase in the temperature at the top. This in turn leads to an increase in both the reflux flow and the amount of product collected. To keep the temperature at the top within the specified range, the reflux flow must be increased significantly
Without a temperature difference, there can be no excess!
So what happens if the tower top temperature exceeds the process control limit and it is difficult to control the tower top temperature through reflux?
If there is too much steam and the condenser is unable to condense it all, it will cause pressure to build up in the tower; not all of the solvent vapor can be condensed, and it escapes through the vent of the condenser
With an excess of steam, it’s not a big problem if it can condense. If the gas flow rate is too high, condensation is incomplete, which leads to material leakage and entrainment; in addition, excessive equipment temperature can pose safety risks
The steam volume is too high, which increases the backflow rate; this can’t go on indefinitely. Excessive steam will cause flooding of the tower; there is an overtemperature and overpressure condition.