150 likes | 190 Views
Controllability of a Granulation Process. Christer Haugland Supervisors: Sigurd Skogestad Vidar Alstad ( Yara Technology Center). Christer Haugland, Modeling and Control of fertilizer granulation process. Outline. Summary process description
E N D
Controllability of a Granulation Process Christer Haugland Supervisors: Sigurd Skogestad Vidar Alstad (YaraTechnology Center) Christer Haugland, Modeling and Control of fertilizer granulation process
Outline • Summaryprocessdescription • Obtaining limit cyclebehaviour as seen at theYara plant • Fitting model to plant data • Simulinkmodel • Furtherwork
Process description • Feed: • Slurry melt • Spherodizer: • Drying • Granulation • Screens • Separation • basedonsize • Crusher • Crushoversize • particles
Recycle mass flow controller • Split range controller
Model • Modeldeveloped in MATLAB • First looked at discretizations in particle sizes • Increased particle classes (no. of discretizations) until the effect on the model was no longer seen. • Limit cycles occurred!
Bifurcation plots d50_mill = 1.95 mm
Plant data compared to model • Too large particle sizes in the system! • Only closed loop data available • Recycle mass flow controller output should also be in the same range as plant data. • Unknown controller tunings. Many unknown parameters
Model fitted to plant data • Trial and error approach • Based on average values of plant data d50 and controller output values • Not able to get the same amplitude in d50 oscillations • Controller output and d50 in the same region as plant data.
Model fitted to plant data Screen 2 Screen 1 New parameters Old parameters
Simulink Model • Particle balance. Recycle controller off. • Particles inn-> Crusher , Particles out -> Product
Simulink Model • Particle balance. Recycle controller on. • Keeping recycled particles constant -> Stable particle balance
Further work • Bifurcation plots with the new model fitted to plant data • Controllability analysis • Look at control structure