Selection of the supercooling temperature at the top of the distillation column
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Everyone, a friend previously analyzed the advantages, disadvantages, and application areas of both hot reflux (partial condensation) and cold reflux (subcooled condensation) in distillation columns. I would like to ask everyone: if cold recirculation is used, by how much degrees is the supercooling?
There is no specific fixed value for this; when cold reflux is used, the reflux temperature is closely related to the operating temperature of the distillation tower. The function of cold reflux is to exchange heat with the upward-flowing gas in the distillation tower, thereby condensing and separating the heavier components carried up by that gas. In this process, it is necessary to ensure that most of the heavier components are condensed and return to the bottom of the tower, while at the same time preventing a large amount of lighter components from being condensed. Therefore, this temperature needs to be determined based on the specific properties of the medium and the operating conditions of the tower! In distillation columns, some reflux is of the bubble-point type, while others is of the subcooled type. The lower the condensation temperature, the higher the efficiency of material separation; however, this also results in a greater consumption of coolant. Therefore, a subcooling of around 3–5° is generally used. The reflux temperature of our distillation column is around 40°C