the fastest possible load change, but the most economical
one.
Remarks. As stated above, chemical processes are
always subjected to disturbances and uncertainties during
operation. Determining the inherent-process characteristics
that enable the process to operate with acceptable performance
is the ultimate objective of any controllability analysis.
Controllability assessment precedes the control system
design during the process design procedure. Thus, the controllability
assessment deals with whether the plant is controllable
and, ideally, also with what is the achievable controlled
performance of the process. How the process actually
is controlled is subsequently dealt with during control structuring
and controller design. Accordingly, this analysis is independent
of the control system imposed on the chemical
process.