ABSTRACT
Properties to be controlled may not be measurable on-line fast enough to allow for a timely action by the manipulated variable. Such properties may have to be inferred from other measured properties. A column product purity or composition, for example, could be inferred from measured column temperatures on a number of trays. The required property is related to the measurements by inferential property correlations whose parameters must be determined. In the compositiontemperature example, the correlation parameters are evaluated from measured temperatures and laboratory composition analysis, and are updated every time laboratory analyses become available.
