coworkers designed the control systems for improving the
controllability of glass manufacture process based on passivity.
116 Garcia et al. presented a controllability analysis of a
low-temperature ethanol reformer based on a cobalt catalyst
for fuel cell application.251 Ramachandran analyzed the controllability
of continuous granulation plants.252 Kalbasenka
analyzed the industrial batch cyrstallizers,253 a controllability
analysis was performed to find suitable process actuators and
to assess their influence on the decisive process parameters
(the process yield and the product properties such as crystal
size distribution and the crystal size distribution width). Perhaps
such studies can provide a basis for applying controllability
analysis to more novel processes. To apply controllability
analysis to realistic processes, especially plant-wide
processes with a high degree of nonlinearity, novel controllability
analysis methods and tools should be developed.
Conclusions
This article presented an overview of controllability analysis
for chemical processes. A detailed description of controllability
assessments and process design methods for improving
controllability characteristics were given. Switchability
analysis is an important aspect of controllability analysis and
was also discussed. Because incorporation of controllability
measures into the early stages of a process design could
make designed processes inherently safer, this has received
increasing attention. The detailed classification of existing
process design methods for improving controllability, including
optimization-based design and controllability indicesbased
anticipating sequential design, were illustrated and discussed.
The advantages and disadvantages of these methods
were described. Because of various constraints and the development
of novel and complex processes, controllability
analysis should be considered together with other aspects.
Future developments in the field of multiobjective optimization-
based analysis for chemical process design requires further
work in the development of more effective optimization
algorithms and new analysis tools.