Control of a fractional distillation column

摘要

A control system is provided for a fractional distillation column where at least a portion of the overhead vapor stream from the fractional distillation column is utilized in a refrigeration and heating system for a process with which the fractional distillation column is associated. The liquid level is an overhead accumulator associated with the fractional distillation column is maintained at a level sufficient to insure that a sufficient supply of the overhead vapor stream from the fractional distillation column is available to supply the refrigeration and heating needs of the process with which the fractional distillation column is associated. Feedforward control based on the flow rate of the feed stream to the fractional distillation column and an analysis of the feed stream flowing to the fractional distillation column is utilized to maintain the desired liquid level in the overhead accumulator associated with the fractional distillation column even where fluctuations occur in the flow rate of the feed stream being provided to the fractional distillation column.