Evaluation of control strategies for fertiliser granulation circuits usingdynamic simulation

A control strategy for fertiliser granulation circuits is developed by empl oying a dynamic model which is based on a sound understanding of granulatio n mechanisms. The overall study of the control strategies includes selectio n of the controlled variables, determination of the control structure and c ase studies. Recycle size distribution is chosen as an easily measured cont rolled variable and a PI controller is implemented in the process. An exami nation for the control of a di-ammonium phosphate granulation process is ca rried out by using the NIMBUS Simulator. The simulation results show the of f-set of the granule mean size and the moisture content caused by the step change disturbance is reduced greatly compared with the open loop simulatio n. The issues for the control of the large time lag and the large recycle s tream are discussed. (C) 2000 Elsevier Science S.A. All rights reserved.