CONTROL STRATEGIES FOR ALTERNATIVE CONFIGURATIONS IN CONTINUOUS INDUSTRIAL GRANULATION PROCESSES

COTABARREN, IVANA; BERTIN, DIEGO; BUCALÁ, VERÓNICA; PIÑA, JULIANA

Sheffield

Congreso; 7th International Granulation Workshop; 2015

Particles Product Group-University of Sheffield

This paper focuses on enhancing the operation of industrial granulation circuits via the design and performance evaluation of different control strategies. Particularly, control strategies were implemented on a urea-granulation flowsheet simulator based on an alternative circuit configuration respect to the often used (Uhde fluidized-bed granulation technology, UFT). The proposed configuration is based on a simulator of the UFT circuit which has been previously developed and validated by our group in a gPROMS modeling environment (Process System Enterprise). This new configuration includes a bypass of fines coming out of the crusher (flowrate and size of the seeds fed back to the granulator), the granulator discharge, the fluidization air temperature and flowrate, and the gap between the crusher rolls as potential manipulated variables. In order to maintain the operation within the desired limits, it is necessary to control the granulator top vacuum pressure, the fluidized bed levels and temperatures, and the mean size and span of the product size distribution. Through sensitivity analysis and/or the Relative Gain Array criterion, the optimal pairing between manipulated and controlled variables was first determined. Subsequently, the proposed controllers were tuned following an optimization-based method (integral of time absolute error, ITAE). All the studied control loops were effective to either eliminate disturbances in the granulation circuit variables or to reach new set-points for the controlled variables. Summarizing, this contribution provides granulation process engineers with useful control strategies for solving typical transient operational challenges.