The development of a composite controller or multivariable control method is very important since some chemical processes, e.g., cascade processes and distillation columns, are high-order systems. Some studies relate to parts of chemical processes that can be reduced to two-time-scale nonlinear systems, e.g., cascades of CSTR, catalytic reactors, and distillation columns. Since some chemical processes can be treated as high-order systems with nonlinear manipulated inputs, the stabilizing control algorithm within a linearization framework has been rarely addressed. Two-input control design methodologies for a broad class of nonlinear systems with time-varying disturbances were proposed. The developed controller features dynamic feedback and static feedback for stabilizing the open-loop unstable system and compensation for the effect of disturbances. The integrated control design with straightforward algorithm can overcome drawbacks in single-input design. However, two-input design employed may offer better control performance and robustness, although the additional input must be achievable and limited to operating costs. The additional input aims to stabilize some unobservable modes and reduce the effort by only one controller used. With an appropriate choice of controller parameters, a general nonlinear system can be transformed into a singularly perturbed system, and then the two-input control scheme can be reduced directly. The merits of the proposed controller system was shown via the demonstrated cascade of CSTR system with inlet perturbations, such that the outlet reactor temperature appears excellent tracking performance, as well as indirectly improving reaction conversion.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)