The issue of feed composition in distillation columns
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With a constant feed composition in the distillation column, what impact does changing the feed from normal temperature to bubble point temperature have on the operation of the column? If so, what measures should be taken? Thank you!
I think that if it is changed to a batch feed, the load on the distillation section of the distillation column will increase, while the load on the stripping section will decrease
When the feed composition to the distillation tower remains constant, switching from a feed at room temperature to a feed at the bubble point increases the load on the distillation section; as a result, more water is required for the top condenser, while less steam is needed for the bottom reboiler. The load on the stripping section decreases. Measures to take: lower the feed inlet position (if there are three feed inlets). If there is only one feed inlet, the only option is to increase the amount of cooling water used and reduce the amount of steam used (the total energy consumption should remain roughly the same).
If the feed temperature is increased to the bubble point, the gas load in the distillation section of the tower will increase; simultaneously, the top temperature of the tower will rise as well. In such a case, if the same product is to be obtained as with feed at normal temperature, it is necessary to increase the reflux rate in order to lower the top temperature of the tower and facilitate the distillation of the product. This increases operating costs and reduces system stability; it is recommended that the original poster not change the feeding conditions lightly. Since the selection of equipment such as your reboilers, condensers, and reflux pumps is based on normal-temperature feed conditions, it is necessary to conduct thorough calculations to determine whether these devices can adapt to a changed feed temperature.