New Hybrid Control Approach for Cascade Temperature Control in Catalyst Regeneration Process

This paper describes an improvement in performance achieved over an existing feedback control system for the temperature control of catalyst bed in chemical reactors. The improvements are focused on devising a new control technique that improves the system behavior against any kind of disturbances. Catalyst regeneration process regenerates the catalyst of a chemical reactor. An important variable, which is to be controlled, is the temperature of catalyst bed. A very high temperature may destroy the qualities of the catalyst, while a low temperature may result in long burning time. The existing temperature control system in use is designed around conventional simple feedback control loop with proportional type of controller. The feedback control technique imposes various limitations like poor time response and relative stability. The control strategy suggested in this paper, involves the use of multiple cascade control loop with advanced fuzzy knowledge based controller and the feed-forward control. The use of two feedback loops in cascade, divides the total time lag present in the system into two parts. This paper details the verification of the comparison between the performance of an existing simple feedback control and an advanced cascade control technique based on fuzzy logic controller, for the catalyst regeneration process at modern continuous process steel plant. The improvement in system performance based on cascade control approach over the conventional one from the point of view of improved time response and relative stability is verified through simulation results