What control methods are used in isomer distillation towers to obtain qualified products?
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Isomers generally have similar boiling points; how can DCS be used for control during distillation in order to obtain qualified products? I would appreciate your advice!
It is not DCS that determines the separation efficiency; rather, an appropriate number of theoretical plates is calculated based on the properties of the isomers. This allows for the determination of the type of packing and other internal components such as distributors, and thus the height of the tower can be determined in order to separate the two substances. If the tower is tall enough, a slightly lower DCS control precision is still sufficient to achieve separation; if the tower is not tall enough, careful operation will not be enough to meet the requirements.
The boiling point and its vicinity – distillation might not be suitable for this
““It’s not DCS that determines the separation effect” — this is the truth. Isomers have similar boiling points, require a larger number of theoretical plates (tower height), and have almost no direct relation to control.
Of course, if distillation is not feasible, methods such as adsorption (for xylene isomers), crystallization, or distillation + crystallization (for nitrotoluene isomers) can also be used.